Was about to get a toy- then I did some research...

[Juranovich]

...and now I seem to have myself a new hobby trying to put together my first ever cnc from scratch! I have no prior experience with cnc’s, but I’ve been looking at getting one for some while now. Mostly for various wood projects I’ve got going on from time to time, but also hoping to get my kids involved and interested in industrial design (I.e. to better understand what actually goes into making things).

Now, having spent countless nights looking at different kits online and ploughing through forums I’ve come to realise that all the kits within my budget come with compromises, many of which I wouldn’t be prepared to pay the asking price for. Luckily, I stumbled upon mycncuk which, to my mind, seems to offer the most helpful and on point advice of any cnc related forum I’ve visited. Actually, it’s the active members here that have (unknowingly) pushed me over the edge and got me worryingly excited about this.

Which brings me to what I’m doing here. I’ve lurked around the forum and stolen a bunch of great ideas which, in turn, has yielded a concrete plan of what I’ll get myself into. For anyone kind enough to drop me some critique, I’ll be posting my initial iterations in the build log thread (I hope that’s the correct one) and hopefully I’ll get started soon enough!

Other than that, cheers to all of you who actively and constructively share your views with us less experienced- I’ve already learnt a ton!

[Chaz]

Welcome and best of luck with your build.

[Juranovich]

Cheers! I can't seem to get my design pictures uploaded (they're resized to requirements and I've tried three different OS) but will post my plans as soon as I get it to work.

[Clive S]

Cheers! I can't seem to get my design pictures uploaded (they're resized to requirements and I've tried three different OS) but will post my plans as soon as I get it to work.

What format are you using? Also you might need to make a couple more posts.

I am sure Lee (forum owner) will pop up and sort it for you

[Juranovich]

I think they were png (I'm using the free version of shapr3d for rough sketching and it only allows for stl exports and screenshots).

[Kitwn]

Welcome to the forum. You'll find plenty of help and advice here.
You have to make a minimum number of posts (10 I think) before you can upload pictures. have a look at the forum rules.

Kit

[NeoMorph]

...
Other than that, cheers to all of you who actively and constructively share your views with us less experienced- I’ve already learnt a ton!

I’ve been operating my machine for a couple of years and if there is one thing I would tell anyone who is designing a CNC... think scenarios where things go wrong. How easy will it be to fix or adjust your machine.

For instance my Ox is great when it works... but when the belts come loose I have to disassemble a lot of the carriage if the Y axis comes loose and don’t get me stared on the holes for the tension adjust on the long rails.

You see you actually have to remove two inner wheel stacks just to get to the bolts that hold the stepper motor in place. It’s just bad design imho. Maintenance tasks like belt tensioning should be simple to do.

So imaging you crash your machine (don’t worry, we all do it). Your carriage is now skewed... how would you realign it to the frame.... I solved that for me by hitting the emergency stop, moving the carriage to one end where I have aligned two end stops... I push the carriage gently against the stops and the release the E-Stop... the motors come online and all I have to do then is run a homing cycle.

Oh yeah, you will need to install limit switches so you can run homing cycles. Definitely makes life easier.

Oh and these are just suggestions from CNC noob... I’m still learning every day... but loving every minute.

[Clive S]

Oh yeah, you will need to install limit switches so you can run homing cycles. Definitely makes life easier.
Just to be clear for the benefit of new users.

limit switches and homing switches do two different things. Although a homing switch can be setup at one end to act as both. ie it is a homing switch when first run (homed) then the software changes it to a limit switch.

Limit switches are nearly at the end of travel on each axis to stop the machine from hitting the hard stops

[Kitwn]

And soft limits are there to stop you accidentally crashing the machine due to any one of a dozen easy mistakes. But they only work only AFTER you have used the homing switches to tell the machine where it is.

[AndyUK]

Welcome to the forum :)

Yeah... this is quite a time-sink (and potentially money-sink) of a hobby.... ;)

Based on your post title, I'm guessing you were thinking of grabbing one of those pre-made Chinese jobbies off ebay?

They get an awful lot of flack (from me too!) but I think they do actually have a place; as long as you're prepared for how pathetic their capabilities are, they're a reasonably inexpensive way of experiencing the CNC process and way of thinking, allowing you to start exploring what you might want out of a machine.

The Shapeokos of the world give the same lessons, but are more expensive to begin with, although probably allow a greater amount of time before you outgrow it.

My first CNC was a simple conversion of a 3D plotting tank (think 40x40x40 work area, but about as stiff as jelly). It taught me lots about GCode, CAD CAM and what I needed from a machine.

[JAZZCNC]

And soft limits are there to stop you accidentally crashing the machine due to any one of a dozen easy mistakes. But they only work only AFTER you have used the homing switches to tell the machine where it is.

That's not quite correct actually. Soft limits will work without a home switch by just hitting Home all, after which home will be where ever the machine happens to be parked. However, it's not advised because then you still crash the machine into the ends. But if your going to fit just home switches then you may as well make them move with the axis and have them double up as Homes and limits.

[Kitwn]

....... However, it's not advised because then you still crash the machine into the ends.

Precisely!
I have one set of switches which double up as limit and homing switches. This is very easy to configure in LinuxCNC. Once the machine has homed itself the soft limits will prevent the limit switches from disabling the stepper drivers (most annoying!) even if I get the gantry out of the way by just pressing the LEFT button on the USB Nintendo game controller (er, sorry, meant to say "sophisticated manual pendant") until it stops.

As Hermione Granger (almost) said "Simple but effective".

[Juranovich]

Wow glad to see so many replies!


I’ve been operating my machine for a couple of years and if there is one thing I would tell anyone who is designing a CNC... think scenarios where things go wrong. How easy will it be to fix or adjust your machine.

This, I'm def a fan of simple solutions. So I've done my best to keep my design free from unnecessarily complicated solutions. Sometimes it might come at the expense of top notch quality, but then again I'm here to learn!


Welcome to the forum. You'll find plenty of help and advice here.
You have to make a minimum number of posts (10 I think) before you can upload pictures. have a look at the forum rules.

Kit

Good to know. Actually, I was lucky there is such a rule as it gave me more time to consider my design (which now is even more developed) :)


Welcome to the forum :)

Yeah... this is quite a time-sink (and potentially money-sink) of a hobby.... ;)

Based on your post title, I'm guessing you were thinking of grabbing one of those pre-made Chinese jobbies off ebay?

Yup, something like that. And I'd probably been quite happy with whatever I would've got had I not dug into it. Nontheless I figure it won't be cheap anyway (time or moneywise) so I might as well make building one a hobby in itself + I'll have to learn the basics of electronics which I've never made time for!

[Juranovich]

As I wait to break the 10 post limit so I can upload a pic of my design for public dissection I'll try posting a couple burning questions I have in this thread.

1. Partly related to neomorph's comment- in an attempt to keep things simple I've considered using fk/ff ball screw supports mounted directly on the end plates/gantry plates, but this would require the steppers to be mounted with spacers (in between the stepper and the other side of the plate). The other option would be to use bk/bf supports mounted some distance away (on the "inside") from the plates, leaving enough clearance for the steppers to be mounted straight on to the plates. Do both work equally well in practice?

2. This might be impossible to answer without more details, but I'll give it a go. I currently have planned about 150mm of Z travel which would make the gantry plates roughly 500mm in height as measured from the X (long) axis side mounted rails to the top (ie the plates would extend a further 100mm below the cutting bed). Does this seem OK or would it be advisable to give up some Z travel in favour of shorter gantry plates?

[AndyUK]

2. This might be impossible to answer without more details, but I'll give it a go. I currently have planned about 150mm of Z travel which would make the gantry plates roughly 500mm in height as measured from the X (long) axis side mounted rails to the top (ie the plates would extend a further 100mm below the cutting bed). Does this seem OK or would it be advisable to give up some Z travel in favour of shorter gantry plates?

You'll always get a stiffer solution with less Z travel, but I wouldn't have said 15cm is unreasonable. Also depends on if the bed is adjustable or not - if not you have to consider the clearance height of any clamps or vises you plan to use. Having said that, it sounds like you're implying a 25cm (500-100-150) tall gantry? Without seeing the design its hard to say, but sounds quite hefty!

[Juranovich]

Sorry, I might have been a bit unclear in my description, essentially the gantry plates would be roughly 60 cm in total height. But what matters, I suppose, is that the gantry would be 18cm + two round linear rails mounted top and bottom adding a further 5cm or so to the overall height of the gantry. While the space between the non-adjustable bed and the bottom of the gantry (including the rail) is 20 cm, the free height from the tip of a typical router bit on a mounted spindle down to the bed is 15cm (when Z is in its top position). Hopefully that cleared thing up a bit!

[Boyan Silyavski]

You should have very clear what you would like to do with that machine. But IMO the best machine for a starter is CNC mini mill. Smaller area but a real machine, not a toy. And will not lose resale value so much. And can make real parts. very good for learning.

Worse thing to buy is crappy Chinese machine and God forbid a belt driven machine.

[JAZZCNC]

God forbid a belt driven machine.

Here we go again.! . . . Have you ever built or used a belt-driven machine.?
For a small router, (or even a basic large machine) then belt drive is a very good solution with high efficiency and low backlash that's reasonably cheap and easy. Yes, maybe not ball screw good but much better than other methods like R&P or cheap lead screws if done correctly. . . . .Don't knock it until you've tried it.!

[JAZZCNC]

1. Partly related to neomorph's comment- in an attempt to keep things simple I've considered using fk/ff ball screw supports mounted directly on the end plates/gantry plates, but this would require the steppers to be mounted with spacers (in between the stepper and the other side of the plate). The other option would be to use bk/bf supports mounted some distance away (on the "inside") from the plates, leaving enough clearance for the steppers to be mounted straight on to the plates. Do both work equally well in practice?

Yes either works fine. Also consider attaching the motors to the screws with belts as it provides a few advatages. It Lowers resonance, allows a ratio and gives flexabilty in location so can turn motors inwards and keep width narrower.


2. This might be impossible to answer without more details, but I'll give it a go. I currently have planned about 150mm of Z travel which would make the gantry plates roughly 500mm in height as measured from the X (long) axis side mounted rails to the top (ie the plates would extend a further 100mm below the cutting bed). Does this seem OK or would it be advisable to give up some Z travel in favour of shorter gantry plates?

With out seeing your design then yes it's not easy to say but 150mm Z travel is standard on router machines I build and 500mm length plates is about right so your not far away.

[NeoMorph]

Here we go again.! . . . Have you ever built or used a belt-driven machine.?
For a small router, (or even a basic large machine) then belt drive is a very good solution with high efficiency and low backlash that's reasonably cheap and easy. Yes, maybe not ball screw good but much better than other methods like R&P or cheap leap screws if done correctly. . . . .Don't knock it until you've tried it.!

100% agree.

Double belting reduces a lot of the stretch too. I glued my lower belt to the aluminium and it really improved the accuracy too.

It all depends on what materials you want to work with. Woods and plastics and cast aluminium (yeah, ALWAYS go with cast if you don’t want to get tons of aluminium welding to your endmills) then belt driven machines are great for learning the ins and outs of CNC... plus it’s cheaper to fix if you have a horrible crash that would warp the screws and ways of a non-belt driven machine.

I had one incident where a glitch decided to rapid in the long axis (X axis on my machine) at crazy speed and it slammed into the limit sensors (thank god I put them in spring mounted blocks) before ramming the hard limits. Then it was skipping gears before the limit switch went “eh what.. WHAT THE F???” Before shutting the machine down.

That’s not so say it was slow to respond... it was just that the incident developed so darn fast that it accelerated into the stops like a crash test dummy machine. If it had been a screw driven machine I would be looking at stripping the whole thing down due to warp... and the cause? A glitch in the gcode plus me messing with the X max rate and inputting 1500000 instead of 1500.000.

CNC baby steps. Belt driven machines are good to learn on as replacing belts is cheaper than replacing ball screws. Now imagine that crash happening to a screw driven machine???? 😱🤯🤬

Butttttt... don’t think that the eBay machines are good value unless you are ready to possibly throw away all that money. Better to buy a machine from a reputable seller in your country who can help.

It may cost a little more but if anything goes wrong they are there to help. I had a bad CNC xPro controller which was exchanged after trying to get it working with the supplier. No cost to me... and sorted FAST!

[norggan36]

Hello and welcome.

[Juranovich]

Yes either works fine. Also consider attaching the motors to the screws with belts as it provides a few advatages. It Lowers resonance, allows a ratio and gives flexabilty in location so can turn motors inwards and keep width narrower.

Originally I was a bit hesitant to this idea (for sake of simplicity), but it grew on me as I considered my design from different angles.

Now, I don't want to go into to much detail before i break the 10 post threshold and can post pictures, but considering I'm planning to make the frame 1000x800mm (effective working area approx. 750x600mm), should I use 1605 ball screws on all axis, or is it better to use 1610 on X and Y (and possibly 1605 on Z)? With belts, I guess, it doesn't matter as much since I could always gear it to suit the purpose, but am I unnecessarily restricting myself if I choose one over the other? I'm thinking of using nema 23 2.4nm steppers (in case it's relevant info) and mainly work with wood (hard and soft) and occasionally soft alloys e.g. aluminium.

In relation to the above, I'm thinking of using base 30 60x120 extrusions for the long axis (for easy mounting of 20mm round linear rails) and 3 cross beams (along the short axis) of 60x60 extrusions mounted flat with the top side of the side extrusions. Essentially the frame would rest on the side extrusions and I'd have an even bed extending over the whole 1000x800 surface. I could also use 60x120 for the cross beams (which would undoubtedly make the frame more rigid), but that would force me to move the belt driving steppers outside the gantry plates (instead of hiding them under the table) which defeats the purpose of keeping a compact design. From your experience(s) would the 60x60 cross beam solution suffice or should I play it safe with 60x120 all around? Mind you, I'm constantly trying to balance performance with costs, hence, I'm inclined not to overbuild just because I can.

[Juranovich]

You should have very clear what you would like to do with that machine. But IMO the best machine for a starter is CNC mini mill. Smaller area but a real machine, not a toy. And will not lose resale value so much. And can make real parts. very good for learning.

I actually stumbled upon another thread where I think you were involved and this idea came up. It's actually not a bad idea as a) I'd have something to learn the basics on b) I happen to know of a (apparently) decent used mill that's for sale c) I'd be able to machine my own alu plates. As of now I'd probably have to have the majority of them made for me...

On the other hand, that would entail spending money on two machines instead of just one...

[AndyUK]

Now, I don't want to go into to much detail before i break the 10 post threshold and can post pictures, but considering I'm planning to make the frame 1000x800mm (effective working area approx. 750x600mm), should I use 1605 ball screws on all axis, or is it better to use 1610 on X and Y (and possibly 1605 on Z)? With belts, I guess, it doesn't matter as much since I could always gear it to suit the purpose, but am I unnecessarily restricting myself if I choose one over the other? I'm thinking of using nema 23 2.4nm steppers (in case it's relevant info) and mainly work with wood (hard and soft) and occasionally soft alloys e.g. aluminium..

Either could work - and there are builds showcasing both - which you lean towards depends on what you want to cut. For woods + plastics, you'll want to lean towards the 10mm pitch screws on that size of machine. If its more fine detail work and metals (in which case you might consider building a mill rather than a router...) you'd want to lean towards the 5mm pitch screws. Its not about how quickly you want the machine to finish jobs, its about cutting at the right speed for the material.

Belts offer some flexibility with ratios, but there are a few things to consider. First, your pitch defines how fast you can go before screw whipping becomes an issue. Look at the following page, and click the blue link at the bottom to open a calculator:

https://www.zappautomation.co.uk/ecalculators.html

A 1605 or 1610 screw will have a root diameter of ~12mm. Using a BK BF setup, a 1000mm screw can get to around 1500rpm before whipping is an issue. That limits our rapids to 7.5m/min on a 1605, or 15m/min on 1610.

Typical stepper motors will be falling off in torque dramatically above 1000rpm = 5m/min 1605 or 10m/min 1610. This is where your belts come in, its about allowing the motor to stay at appropriate RPMs for the speed (or torque multiplication).

Now, I'd personally aim for rapids in the 7.5-10m/min range for a wood router, which suggests 10mm pitch screws, but some people are happy with the 5m/min.

As for the Z axis, the travel is massively reduced so large rapids arn't an issue. A finer pitch should give slightly higher accuracy and holding torque at the correct Z location, so I'm all for fine pitch Z screws. 1605 should be fine.

Those motors sound a little weak to me. You should use the motor calculation sheet to determine what you need. Mines a similar size, and I use 2x2010 X screws (2x4nm low-inductance nema23 steppers) and a 1610 Y screw (3.1nm).

[Juranovich]

Those motors sound a little weak to me. You should use the motor calculation sheet to determine what you need. Mines a similar size, and I use 2x2010 X screws (2x4nm low-inductance nema23 steppers) and a 1610 Y screw (3.1nm).

I'm at that stage where I think I've figured out the basic mechanics of a CNC, but I now start to realize all the intricacies of the fine details. So thanks for pointing me in the right direction. I suspect I'll go for 1610 on X and Y to avoid whip and keep the 1605 on Z for precision. As I decide on the final gantry design (and the associated weight) I'll get back to the motor calc to figure out the steppers needed. Just one question though, if I have two steppers driving the long axis, should I input half the total weight of the gantry in the calculator?

Also, you don't happen to have any comments on the frame?

[AndyUK]

If I have two steppers driving the long axis, should I input half the total weight of the gantry in the calculator?

Good question. It's a topic worth discussing. My personal view is that you should double the screw inertia (you have two screws to spin), but also double the motor torque (two motors, after all!)


Also, you don't happen to have any comments on the frame?

Keep posting and I'll comment when you've posted some pictures of your design :) I'm quite a fan of extruded aluminium profiles, it makes the whole thing a lot easier - my gantry went together in hours, my steel and epoxy X axis took weeks. I don't think you can 'overbuild' though...

[Juranovich]

Good question. It's a topic worth discussing. My personal view is that you should double the screw inertia (you have two screws to spin), but also double the motor torque (two motors, after all!)

That sounds much more logical than my suggestion as the weight is naturally not disappearing anywhere... I'm now lacking a homer simpson "duh" emoji for my question! :)

[Boyan Silyavski]

Here we go again.! . . . Have you ever built or used a belt-driven machine.?
For a small router, (or even a basic large machine) then belt drive is a very good solution with high efficiency and low backlash that's reasonably cheap and easy. Yes, maybe not ball screw good but much better than other methods like R&P or cheap lead screws if done correctly. . . . .Don't knock it until you've tried it.!

Here we go again, my first machine was belt driven and aint nothing bad with it, just learn how belt stretches on each material and each temperature... Of course you will say if properly calculated will not happen and i will tell you that for same price it could be ball screw.

Why don't you relax and stop supervising me what i say, it's just an opinion. I am not pretending like you to be the final word on everything

[JAZZCNC]

Andy I'm quoting you but please don't think I'm having a pop at you or knocking what you said. I mostly using the quotes to point other factors out and clear some things up.


A 1605 or 1610 screw will have a root diameter of ~12mm. Using a BK BF setup, a 1000mm screw can get to around 1500rpm before whipping is an issue. That limits our rapids to 7.5m/min on a 1605, or 15m/min on 1610..

Ok well forget this because it's not that simple, there's too many factors involved which make these calculators of much use to a real-world DIY machine. I've built machines that use 16mm dia 10mm pitch screws at 1100mm that will happily reach 25+Mtr/min without whipping. How they are aligned and ball-nut mount fixturing etc all kick in and screw these calculations up. Similair is true of the Motor calcs as well, I've seen them things spit out stupid numbers.


Typical stepper motors will be falling off in torque dramatically above 1000rpm = 5m/min 1605 or 10m/min 1610. This is where your belts come in, its about allowing the motor to stay at appropriate RPMs for the speed (or torque multiplication).

Belts can be used for this reason but it's not the main reason why I use them.
There are two main reasons why I use belts.
#1 Is to allow me to use a higher pitch screw and apply a 2:1 ratio which then lowers the screw speed by half so whip is lowered. Torque is doubled due to ratio but is offset because the linear torque of higher pitch is lower, one cancels the other in effect. I mostly use this approach on longer machines.

#2 Is to lower the affects of resonance on the motors/drives. This gives a much smoother running motor and often allows higher RPM because the drives are not having to deal with resonance issues. Don't underestimate resonance and how it can affect a stepper motor, it can literally cripple a motor and half it's RPM.



Now, I'd personally aim for rapids in the 7.5-10m/min range for a wood router, which suggests 10mm pitch screws, but some people are happy with the 5m/min.

Now, this is where it gets sticky and motor/screw selection becomes very important.
For a balanced machine your better to size motors and screws not for rapid speed but in such a way that your cutting with the motors at an RPM that gives good torque while cutting.
Ideally, you'd use the Motor Torque/speed curve graph to help select the right screw pitch to give the feeds your most likely to cut at for the materials your cutting mostly. But most Stepper manufacturers are about as trustworthy as politicians so you can't believe any of the bull shit they show. Plus lots of other factors come into play like voltage they are being run at and how wired etc.

So we know through experience that a typical NEMA 23 motor wired in parallel with voltage in the 60-70v region above 1000rpm torque starts to drops off and above 1200rpm drops quickly to about 1500rpm then stalls can occur.

Now for a router cutting mostly soft materials or man-made boards using a carbide cutter and extraction for chips, will be between 6-10 Mtr/min. Now the higher end won't work with a 10mm pitch because the motor would be spinning at 1000rpm where torque is low and dropping away. So we need a higher pitch or motors that spin faster with torque ie: servos.
So keeping with steppers then we need to change the pitch, the next common pitch would be 16mm. This gives 10,400mm/min at 650Rpm which is a little too low rpm at this speed, 750rpm would be a nicer figure but this gives 12,000mm/min. So here's where a small ratio on the belts would kick in and allow us to balance the machine up. Reclaim a little linear torque and lower screw speed. Plus the added advantage of better resonance handling.

So a 1.25:1 ratio would be like a 12.8mm pitch which at 750rpm would give 9600mm/min which is a nice area with good amount of torque. With rapids in the 15Mtr/min range at 1200Rpm and without getting too close to the stall point, which on a stepper at 70vdc is around 1300-1500rpm dependant on alignment etc. However, because of the ratio, the screw speed would be around 960Rpm so we are still ok regards whip. We have also gained back a little torque from the ratio.

So it's winner, winner chicken dinner and we have a nice balanced machine. That will fly like the wind and cut at correct feed rates with good amount of torque left.

However at DIY level most don't cut correctly or with carbide tooling or chip extraction so they manage with 10mm pitch and just cut slower. However, if they ever decide to cut correctly or with carbide tooling etc then they will struggle or fail. The balanced machine above will cover all bases with only real loss being slightly less resolution.



As for the Z axis, the travel is massively reduced so large rapids arn't an issue. A finer pitch should give slightly higher accuracy and holding torque at the correct Z location, so I'm all for fine pitch Z screws. 1605 should be fine.

Those motors sound a little weak to me. You should use the motor calculation sheet to determine what you need. Mines a similar size, and I use 2x2010 X screws (2x4nm low-inductance nema23 steppers) and a 1610 Y screw (3.1nm).

Spot on, on both accounts, except using the motor calculator. The key to speed is low inductance motors with plenty of volts wired in parallel.

[JAZZCNC]

Here we go again, my first machine was belt driven and aint nothing bad with it, just learn how belt stretches on each material and each temperature... Of course you will say if properly calculated will not happen and i will tell you that for same price it could be ball screw.

We do agree that ballscrews are better and not much more money. But I don't agree with telling someone NOT to use them with a statement like "God forbid a belt driven machine." because they are not that bad when done correctly with correctly sized belts. It's a perfectly good route for a first time builder on a budget who doesn't want to get into importing ballscrews etc from China.


Why don't you relax and stop supervising me what i say, it's just an opinion. I am not pretending like you to be the final word on everything

I don't pretend to be the final word on everything.! . . . .I AM THE FINAL WORD. . . :joker::joker::hysterical:

Chill out Boyan, I still Luv ya Dude, and it's only for the sake of others we do what we do.! :beer:

[NeoMorph]

Another thing to think about is I am 100% guaranteeing that any machine you design and build will end up getting modified in some way after you get your first cut chips.

I think I spent the first year either pulling my machine apart and making minor alterations like packing the interior of the extrusion and bolting the gantry beams together to increase rigidity and reduce harmonics, to bigger alterations like removing the old Z axis and replacing it with a stronger C beam and replacing the aluminium gantry uprights with strong steel ones. This reduced a LOT of design problems with my original build yet I’m still not 100% happy.

What I mean is, until you get some experience under your belt it’s hard to know what you want from what you NEED to make your machine do what you want. I’m still very much a novice yet have managed to improve my machine a lot over the last few years.

[Juranovich]

So a 1.25:1 ratio would be like a 12.8mm pitch which at 750rpm would give 9600mm/min which is a nice area with good amount of torque.
[...]
Spot on, on both accounts, except using the motor calculator. The key to speed is low inductance motors with plenty of volts wired in parallel.

Just to get my head around this- if 1m/min and 750rpm are good values for general wood working, what would be the sweet spot for detailed work (eg 3D engravings in wood) or the occasional aluminium job?

With regards the stepper size- what would be the optimal torque rating for the machine to be balanced (considering the consensus seems to go against 2.4nm)?

On a side note- thank you for the detailed discussion, since I’m new to this it sometimes feels I’m designing blindfolded as I don’t even know what parameters I should be aiming for!

[Juranovich]

What I mean is, until you get some experience under your belt it’s hard to know what you want from what you NEED to make your machine do what you want. I’m still very much a novice yet have managed to improve my machine a lot over the last few years.

I hear ya! But isn’t it lovely to overthink things especially when you don’t yet know anything? Even though I constantly pull myself out of that rabbit hole, I keep falling in...


.I AM THE FINAL WORD. . . :joker::joker::hysterical:

Also- I AM THE LAW!!!

[JAZZCNC]

Also- I AM THE LAW!!!

No No No I'm most definitely more THE OUT LAW.!!


Just to get my head around this- if 1m/min and 750rpm are good values for general wood working, what would be the sweet spot for detailed work (eg 3D engravings in wood) or the occasional aluminium job?

Well not sure where your getting 1m/min from but giving specifics for sweet spots for things like 3D work isn't really possible because it's material and cutter dependant, plus 3D work requires a slightly different machine setup to get the best from it.
3D work tends to be lots of really short fast moves with very light depths of cut, so you tune the machine differently and biased more towards acceleration than speed if doing lots of 3D work.
Velocity is not so important for 3D because the moves are very short so even if you had a High feed rate set you'll never actually reach that feed before your at the end of the move and onto the next. So to increase the feed rate it's actually better to lower velocity and increase acceleration. So now the machine can accelerate faster and reach a higher feed rate before the next move comes around.
Because of the nature of 3D jobs being made up of lots of short moves a properly setup machine can shave hours off a job. The simple rule is that you can't have both high acceleration and high velocity, setup is always a trade-off between the two.

Aluminum on the other hand just requires correct feeds and speeds based on the tool and material type and machine setup don't really play much part because the feed rates are so low compared to wood or soft materials there is plenty of torque available with a machine set up for a balance of speed and acceleration.

For instance, I have 2 different profiles one for general work with a balanced setup of speed and acceleration, the other set biased towards acceleration just for 3D work. When doing 3D work I just load the different profile and I'm set up for 3D work.

Now if you want me to make this simple for you then here's what I would use in the machines I build for general woodworking/aluminum use.

16mm Dia x 10mm Pitch screws for machines under 1000mm length with 1:1 ratio using belts to connect to motors. 20mmDia x 20mm Pitch with 1.5:1 Ratio for machine up to 1600mm.

NEMA 23 4Nm for 16mm and 20mm with twin/screws motors. For 20mm with single screw then 6Nm Nema34. Both with coils wired in parallel.
Look for motors in the 2- 4Mh inductance range when wired parallel.

50Vac or 80Vdc Digital Drives with 68Vdc PSU for Nema 23. NEMA 34 with 80Vac or 100Vdc drives. Both using Toroidal Transformer based PSU.

These are proven specs used on machines I build which are used for cutting materials ranging from cardboard to Aluminium and Brass on a daily basis working 12hr plus days 7 days a week in some cases.

[NeoMorph]

I hear ya! But isn’t it lovely to overthink things especially when you don’t yet know anything? Even though I constantly pull myself out of that rabbit hole, I keep falling in...



Also- I AM THE LAW!!!

My problem is when I overthink, it develops feature-creep in any of my designs and a simple rowboat turns into the Titanic (with associated problems included). 😳

If there is one piece of advice I could give it is if you are aiming to make mainly wood and soft material things GO BIG... as in get as big a footprint for your XY as possible. If you are aiming to make parts out of aluminium and steel... then GO SMALL as smaller equals more rigidity. As most hobby CNCers can’t afford a cast iron bed or have the skills of people like This Old Tony then a small mini-mill is actually better.

What threw me about bed size was how much you lose to the gantry and the dust boot. As I put mine into an enclosure I also wish me from the future had turned up and convinced myself to make the enclosure taller to give the dust extractor hose and router power room to move easier (I found keeping the mains lead away from the other wiring stopped any spurious signals getting onto the limit switch wiring... before I had the thing triggering random alerts all the time).

I also put onto isolation into the limit switch lines. I can’t remember the last time I had a spurious signal get through and trip the alarm.

[NeoMorph]

50Vac or 80Vdc Digital Drives with 68Vdc PSU for Nema 23. NEMA 34 with 80Vac or 100Vdc drives. Both using Toroidal Transformer based PSU.

These are proven specs used on machines I build which are used for cutting materials ranging from cardboard to Aluminium and Brass on a daily basis working 12hr plus days 7 days a week in some cases.

*DRRRRRRRROOOOOOOOOL*

I would love drives like these. Unfortunately not everyone can afford drives and controllers that can handle them.

I’m disabled person who had to take medical discharge in my late 20’s because of a deformed gene causing something that is now known as Hypermobility Spectrum Disorder.
So I basically live on a disability pension. Saving up for my Ox took me two years before I could order it... but I’m glad I did. Ooznest manuals are simply the best (especially when stoned on morphine 😂).

[Juranovich]

Well not sure where your getting 1m/min from but giving specifics for sweet spots for things like 3D work isn't really possible because it's material and cutter dependant, plus 3D work requires a slightly different machine setup to get the best from it.

My bad, meant to say 10m/min... effects of nightly writing...



I also put onto isolation into the limit switch lines. I can’t remember the last time I had a spurious signal get through and trip the alarm.

Of what I can see online non-isolated wiring seems to be quite an issue. Luckily, the electronics part is still some time away as that is the part I'm the least competent in (or more accurately "incompetent") and will probably be the most frustrating bit :)

Moving on to great news (for me at least) I’m finally able to post pictures of my design which is heavily based on ideas stolen from this forum! I planned on doing it in the build log section, but seeing the attention this thread has got I figure I might just keep it here (please correct me if I’m doing this wrong!).

So the basics:

- Total dimensions of the frame is 1000x800mm and gantry height 650mm as measured from the bottom of the frame to the top of gantry beam.
- The Z carriage is roughly 450mm high (extending some 150mm above the top of the gantry beam) and 200mm wide with 150mm travel (bearing blocks 300mm apart in the Z and 200mm in the X direction)
- frame consists of 60x120 alu extrusions on the sides and 3pcs 60x60 extrusions across (easy mounting of 20mm round linear rails ;) )
- gantry beam also 60x120 extrusions in L shape
- gantry plates and Z axis made out of 20mm alu, the thinner end plates/stepper mounts are 5mm alu
- the bearing blocks on the gantry plates are 250mm apart
- as discussed above 1610 or 1616 ballscrews drive X and Y, while 1605 will suffice on Z
- NEMA 23 (perhaps 4nm) on all axis as well as 20mm round linear rails
- Haven't decided on the spindle just yet, but should be able to carry something like a 2.2kW spindle (i.e. 5kg or so)

NB! All mentioned dimensions are not precise to the mm, but gives a good indication of the general size. Neither is everything perfectly aligned. I’ll anyway sort out the details as I make the final drawings in fusion. Also- I’ll model the final (balanced) version of the gantry plates as the gantry beam/Z axis design is finalised. Also2- stepper mounting plates will require adjustable fastening slots.

27119

27120

So to the specific questions I have in mind, I'll leave out the ones already previously discussed:

- Frame; I quite like the 60x60 extrusions across the frame as they give me clearance below the table (eg for X axis steppers), but would it be too flimsy? Looking at it now, I have quite some weight on the gantry vs the frame. Maybe worth beefing up the frame with 60x120 instead, or at least the two furthest to the front, leaving clearance at the back for steppers...?

- Gantry/end plates; online consensus seems to dictate 20mm gantry plates, but what about Z mount? Is 20mm overkill and would 15mm do in a machine this size? The end plates/stepper mounts are 5mm (as commercial stepper mounts seem to be in that range). As they're not subject to any excessive forces in my design I suppose 5mm is enough. Essentially they're only carrying steppers and the odd limit switch as well as providing additional stability in the corner joints of the frame.

- Other comments/critique?

[JAZZCNC]

*DRRRRRRRROOOOOOOOOL*

I would love drives like these. Unfortunately not everyone can afford drives and controllers that can handle them.

I hear what you are saying but £40-45 isn't a massive amount of money for a good drive. I've used lots of these low budget machines they are great value and work great. They cover a large range of motors including Nema32 upto 8Nm.

https://www.ebay.co.uk/itm/2DM860H-2phase-NEMA23-NEMA34-Stepper-Motor-Driver-32bit-DSP-DC80V-1-5-6-0A/401403682399?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

[JAZZCNC]

Going to show you some machines I've built that are all the same design but slightly different in size or Z-axis type/length etc dependant on usage but all share the same profile size. 45 x 90.
These machines were designed solely for woodworking and range in cutting area size from 600x400 to 1300 x 700 with a mixture of single or twin screws. However, all of them will happily cut aluminum as you'll see from a couple of pictures sent to me by customers.

Now I'm not showing you these and saying this is how you should build your machine but what I am showing is that this kind of profile size will easily do what you need so don't go stressing about if your 120 x 60 is strong enough or not. What's more important is how it's used ie: L shape gantry bolted together etc.
Some of these machines are used for business and running 12hr days 6 day weeks and have been doing so with minimal maintenance for several years.

Can I also strongly advise you to drop the round rail and go with profiled Linear rail. It's much much better and far less hassle. Don't spoil a potentially great machine for a few Euro more. You'll also get the extra back when you come to sell it as you'll be able to ask more for the machine and it will appeal more to those who know what to look for.

Also, move the ball-screw on the gantry to the top and motor below to keep the length of the drop plate to the shortest possible. Another thing you need to be aware of and one of the reasons why I use the Bosch Rexroth style profile with slot spacing at 45mm is that it suits BK/BF12 bearing bolt spacing. This means you won't have to make mounting plates or mess around drilling the profile.
It's these little details that can easily screw your ideas up or make things much harder than they need to be.!!


27132271312713027129271282712727126271252712427123 271222713327134

[Juranovich]

Going to show you some machines I've built that are all the same design but slightly different in size or Z-axis type/length etc dependant on usage but all share the same profile size. 45 x 90.

[...]

Can I also strongly advise you to drop the round rail and go with profiled Linear rail. It's much much better and far less hassle.

[...]

Also, move the ball-screw on the gantry to the top and motor below to keep the length of the drop plate to the shortest possible. Another thing you need to be aware of and one of the reasons why I use the Bosch Rexroth style profile with slot spacing at 45mm is that it suits BK/BF12 bearing bolt spacing. This means you won't have to make mounting plates or mess around drilling the profile.
It's these little details that can easily screw your ideas up or make things much harder than they need to be.!!


First off- those are some slick looking machines! Also, I never considered using a cross beam under the frame for dual stepper set-ups.

The round vs profile rail debate is one that has had me torn the most. Undoubtedly profile are superior in theory, in practice, however, I've been somewhat put off by the many worst case scenarios people have posted about when ordering the Chinese kind (which I strongly suspect is the only kind my budget allows). Second, being a first timer, I was hoping to get slightly more parallel mounting tolerance with the round rails (bc self alignment), and they provide more room for mounting ball screws on the same face (although that could also be achieved by spacers on the profile carriages). I'm curious though, in what way do you find profile to be less of a hassle?

Considering cost, downsizing to 45x45/90 extrusions might free up some funds that could be used on profiles... I might just have to bring out the famous abacus!

With regards the bk/bf12, I thought bolt spacing was something like 46mm in which case standard t-slot nuts wouldn't work? Or is it merely a case of using good ol' force?

I long favoured flipping the ball screw and stepper positions, but figured ball screw placement as centrally as possible relative to the gantry rails took precedence over drop plate length.

[JAZZCNC]

The round vs profile rail debate is one that has had me torn the most. Undoubtedly profile are superior in theory, in practice, however, I've been somewhat put off by the many worst case scenarios people have posted about when ordering the Chinese kind (which I strongly suspect is the only kind my budget allows).

This is the problem people only focus on those who have had issues, probably because they shout the loudest, but for everyone that as an issue there are 100's more who haven't and work perfectly fine.
Chinese VFD's and spindles being a classic case, I've lost count of how many sets of VFD/Spindles I've fitted and I've had about 3 failures in 10+yrs and those weren't all due to quality but more user error or wiring issues.
I was probably one of the first in UK to use the Cheap Chinese Linear rails and again I've fitted dozens of sets without any issues, Now I fit Hi-win because the price difference isn't too great, but both come from China so don't be put off. Either of them are far superior to round rail and worth the extra, trust me on this you won't regret buying them.



Second, being a first timer, I was hoping to get slightly more parallel mounting tolerance with the round rails (bc self alignment), and they provide more room for mounting ball screws on the same face (although that could also be achieved by spacers on the profile carriages). I'm curious though, in what way do you find profile to be less of a hassle?

Not quite sure what your meaning by Less hassle.? Less hassle than what.? Compared to using steel it's lot less hassle for obvious reason, try drilling and tapping 150 x M5 holes in steel and you'll understand this quickly.! . .Lol

If you are referring to my comment about using 45x90 because of the slot spacing being less hassle. Then I mean it's less hassle than having to make plates which first bolt to the profile so you can then mount the BK/BF bearings onto. Or having to Drill and tap the profile directly, which don't advise doing because never works out good. Like on this gantry that uses 40mm spaced slots and BK15 bearings with larger hole spacing.
27138



With regards the bk/bf12, I thought bolt spacing was something like 46mm in which case standard t-slot nuts wouldn't work? Or is it merely a case of using good ol' force? .

The holes allow just enough wiggle room so that it works ok.


I long favoured flipping the ball screw and stepper positions, but figured ball screw placement as centrally as possible relative to the gantry rails took precedence over drop plate length.

I find comments you've seen made like these are made mostly by armchair theorists who have probably never built a machine.!
Because in the real world the difference between them is so negligible that you'll never see or notice any difference in how the machine performs. I've built all kinds of machines in all possible configurations and I've yet to see one that stands out to even slightest degree that says that's the best way.

End of the day if it fits your design best to have it raised up a little higher then go with it because you won't notice any difference if struggle on and have it the so-called "Optium" position.
The reason I say move it up is that being shorter it won't vibrate as much, which then goes into the screw, which then goes into the motor etc.
Also because the bracket is actually fastened to the top bearing plate anyway, the so-called optimum center position doesn't apply because the forces are being placed on the top bearing plate, not into the center of the Z-axis rear plate which is considered the Optimum position. So having it short means the forces are moved closer to the actual bearing plate which is what's being moved and makes everything that little bit stiffer.

Again don't stress over this stuff because it's not a game-changer or disastrous if not in the optimum place, you WON'T notice any difference. The little details like being stiffer or better-placed screws, motors, switches, etc make for a better more reliable machine than if a ball-screw isn't quite in the Optimum place.

[Boyan Silyavski]

First off- those are some slick looking machines! Also, I never considered using a cross beam under the frame for dual stepper set-ups.

The round vs profile rail debate is one that has had me torn the most. Undoubtedly profile are superior in theory, in practice, however, I've been somewhat put off by the many worst case scenarios people have posted about when ordering the Chinese kind (which I strongly suspect is the only kind my budget allows). Second, being a first timer, I was hoping to get slightly more parallel mounting tolerance with the round rails (bc self alignment), and they provide more room for mounting ball screws on the same face (although that could also be achieved by spacers on the profile carriages). I'm curious though, in what way do you find profile to be less of a hassle?
.


The square rails for me are may be the most important part of the machine in the long run, so there should not be any doubts about that. In fact better buy a smaller size square rails than round rails. mean 15 instead of 20 size , if machine is not intended for heavy duty use . You can always use one carriage more as they are cheap. rail is heavy hence expensive to ship. You get what i say?

About the Chinese square rails, if you buy from a good factory they are same or very similar quality like the Hiwin. You may need to clean a carriage or similar, but most important is to be from a good place.

I buy from these guys https://es.aliexpress.com/store/822038 12 and 15 size. Have not bought from them 20 size , but their rails are very good quality and price. Custom size also, contact them. make sure to buy the long carriages.

[Juranovich]

This is the problem people only focus on those who have had issues, probably because they shout the loudest, but for everyone that as an issue there are 100's more who haven't and work perfectly fine.

Typical case of selection bias... This is what they warned us about in uni!


Not quite sure what your meaning by Less hassle.?

You said that profile rails are better and less hassle, but I think I got the drift now.


The square rails for me are may be the most important part of the machine in the long run, so there should not be any doubts about that. In fact better buy a smaller size square rails than round rails. mean 15 instead of 20 size , if machine is not intended for heavy duty use . You can always use one carriage more as they are cheap. rail is heavy hence expensive to ship. You get what i say?

[...]

I buy from these guys https://es.aliexpress.com/store/822038 12 and 15 size. Have not bought from them 20 size , but their rails are very good quality and price. Custom size also, contact them. make sure to buy the long carriages.

I hear and thanks for the link (and thanks to everyone who's provided useful links to vendors). Theoretical modelling is one thing, but sourcing good materials is always extra hard when you lack experience. Much appreciated!

[Juranovich]

A quick update:

I did some modelling last night based on profile rails so I now have two options. Next I'll compile a shopping list in order to make a price comparison between the two.

Do any of you have suggestions as I plunge into the endless mass of online stores? Preferably suggestions you have personal experience with...I reckon I can always shop at the european stores for fairly safe choices, but I'd be super interested to hear of specific "chinese" vendors/products which might save me a penny.

Below I've compiled a list of recommended vendors/products I've come across on forums (I'll post these so as to avoid duplicates, but also as reference for others that might come across this thread looking for buying advice).

Extrusions: motedis, kjn

rails/ballscrews: https://es.aliexpress.com/store/822038, BST Motion on Aliexpress, linearmotion on ebay

Steppers: https://www.aliexpress.com/store/1907567?spm=a2g0o.detail.100005.2.569f5bd5XOOljj

Motion controllers/BoBs/electronics: CNCDrive

Stepper drives: https://www.ebay.co.uk/itm/2DM860H-2phase-NEMA23-NEMA34-Stepper-Motor-Driver-32bit-DSP-DC80V-1-5-6-0A/401403682399?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

Spindles: Teknomotor (price worthy (?) italian brand), Huan Yang Shop on AliExpress

General european cnc related stores: zappautomation, dold mechatronik, sorotec, cnc4you

EDIT: Added Lichuan under steppers, Huan Yang under spindles, cnc4you under general and fixed boken ebay link under stepper drives.

[AndyUK]

You can get a Chinese spindle and VFD kit from BST linear too. As always email directly for a quote, mention this forum.

Steppers, ZappAutomation, Cnc4you, and I think people have used Stepperonline (they advertise on here at least)

Stepper Drivers I got from Zapp, Gary the owner posts on here occasionally with a decent discount code.

KJN also do extrusions.

[Juranovich]

You can get a Chinese spindle and VFD kit from BST linear too. As always email directly for a quote, mention this forum.

Steppers, ZappAutomation, Cnc4you, and I think people have used Stepperonline (they advertise on here at least)

Stepper Drivers I got from Zapp, Gary the owner posts on here occasionally with a decent discount code.

KJN also do extrusions.

Thanks, I'll have a look at those!

[Chaz]

A quick update:

I did some modelling last night based on profile rails so I now have two options. Next I'll compile a shopping list in order to make a price comparison between the two.

Do any of you have suggestions as I plunge into the endless mass of online stores? Preferably suggestions you have personal experience with...I reckon I can always shop at the european stores for fairly safe choices, but I'd be super interested to hear of specific "chinese" vendors/products which might save me a penny.

Below I've compiled a list of recommended vendors/products I've come across on forums (I'll post these so as to avoid duplicates, but also as reference for others that might come across this thread looking for buying advice).

Extrusions: motedis

rails/ballscrews: https://es.aliexpress.com/store/822038, BST Motion on Aliexpress, linearmotion on ebay

Steppers: ??

Motion controllers/BoBs/electronics: CNCDrive

Stepper drives: https://www.ebay.co.uk/itm/2DM860H-2...72.m2749.l2649

Spindles: Teknomotor (price worthy (?) italian brand)

General european cnc related stores: zappautomation, dold mechatronik, sorotec

Certainly the Teknomotor / HSD spindles are good but are pricy. All depends on if you need ATC or want to change tools manually.

[Juranovich]

Certainly the Teknomotor / HSD spindles are good but are pricy. All depends on if you need ATC or want to change tools manually.

Thanks for pointing that out! Among European brands (the few I've come across) I find them to be fairly well priced. But maybe you compare them to Chinese models?

On a side note, I never considered getting any electronics from China out of fear of bad quality, but I'm starting to consider my position.

[Chaz]

Thanks for pointing that out! Among European brands (the few I've come across) I find them to be fairly well priced. But maybe you compare them to Chinese models?

On a side note, I never considered getting any electronics from China out of fear of bad quality, but I'm starting to consider my position.

Yep, compared to the cheaper Chinese stuff where quality can range from 'OK' to bad. Keep in mind, even stuff that we consider good like 'Panasonic etc' is almost always Chinese.

[Chaz]

For info, I currently run a 6.8 KW HSD Spindle on my Concrete mill. If you look up my build thread (search for Thor), you will find it. I started with a 4KW Chinese spindle which worked OK. Low / no torque and ER collets, found a 2nd hand HSD spindle and not looked back.

[NeoMorph]

For info, I currently run a 6.8 KW HSD Spindle on my Concrete mill. If you look up my build thread (search for Thor), you will find it. I started with a 4KW Chinese spindle which worked OK. Low / no torque and ER collets, found a 2nd hand HSD spindle and not looked back.

The problem with hobby CNC machines using full sized spindles is weight. For example the reason most router based CNCs use router is because of weight either bogging the gantry down or causing the Z-axis to fall (like the Shapeoko, Ox etc). I think the Shapeoko actually used a SPRING at one time to help keep the router from dropping and not being able to get back up again. So a proper spindle is out of the question.

New builders also don’t take into account the weight of water in water cooled machines which is why it’s better to use an air cooled one on a smaller hobby machine. Plus water is another thing I would want to keep away from wood. I got some lubricant on my waste board the one time and it had to be replaced because it swelled up over night.

I think everyone I know of (bar one who went water cooled and had to go double belt and larger stepper motors before it would stop bogging down) has gone the air cooled spindle route. But if I could afford all metal underside and stronger steppers or drives there would be no question. In that case it would be water cooled all the way.

At the end of the day it all comes down to cost.

[Clive S]

New builders also don’t take into account the weight of water in water cooled machines which is why it’s better to use an air cooled one on a smaller hobby machine. Plus water is another thing I would want to keep away from wood. I got some lubricant on my waste board the one time and it had to be replaced because it swelled up over night.

I take it you use an air cooled radiator in your lounge then so it does not ruin the carpet

[Kitwn]

I use the popular 2.2KW water cooled spindle moved by a 1610 ballscrew which does fall slowly under it's own weight when the stepper motor power is removed. Part of my SOP is to put a prop under the Z axis before powering down the control box and removing it again after power is back on. It's not really a problem and I would expect to re-home after an e-stop anyway. No water leaks so far either.

[NeoMorph]

Oops... double post.

[NeoMorph]

I take it you use an air cooled radiator in your lounge then so it does not ruin the carpet

Funny you should say that. A radiator leaked all over my hall about a month ago. Had to throw out the carpet.

Seriously though... it’s the same with water cooled PCs. It’s freaking great when it works but in a CNC it has to deal with the carriage moving back and forth. If you have an all metal CNC you don’t worry if you get a leak. You fix the problem and wipe up the spill. With a wood base CNC it’s going to swell the wood and we all know how it’s going to affect accuracy after that. It means replacing the spoilboard, having to resurface etc. It’s faff you can do without if you use air cooled spindles.

But like I said... if I ever build a metal based one I’m going for an auto-change water cooled, pneumatic drawbar spindle... they kick ass (watch Marco Reps on YouTube).

Edit: Regarding my worry about leaks... I’m slightly OCD about things going wrong after year 1 where pretty much everything did go wrong. The controller was going beserk every so often, the axes would randomly stop working, I had to keep uploading grbl because it was getting corrupted. Drove me nuts.

Took ages to track down... the cause was a link of LED strip lighting that was in my enclosure. It was only after reaching into the CNC the one time that I notice the lights were pulsing randomly in one corner. I thought to test it with another of my 12v psu blocks and hooked it up... and killed ALL the lights in my enclosure. Turned out I used a 24v one instead of a 12v and caused the lights to come on, do some freaky stuff before flaring any dying.

But ironically killing those lights fixed my CNC... it’s run smooth as silk since. I did have to buy some more lights but it’s running fine so it’s money well spent.

So yeah... I tend to still worry a lot.

[AndyUK]

I take it you use an air cooled radiator in your lounge then so it does not ruin the carpet

The pedant in me wants to point out that yes, my radiators are air-cooled. They're also water-heated!

[JAZZCNC]

Sorry I know this is not exactly topic related but I'm not standing by and not saying anything on something which is SO WRONG and will potentialy lead others in wrong direction.


New builders also don’t take into account the weight of water in water-cooled machines which is why it’s better to use an air-cooled one on a smaller hobby machine.

A complete load of rubbish, do you know how much water is actually inside a water-cooled Spindle.? approx 250ml or 250grams.! How much does a fan and cowel weigh.?
If the Z axis can't handle that little extra weight then it needs re-thinking.! . . The truth is that if your Z-axis is this weak you cannot fit a Spindle of this size, it's got nothing to do with how it's cooled.

Your comments regards leaks and the damaging the bed is just laughable. They rarely leak when fitted correctly, I've fitted 100+ sets and never had one leak in use unless something caused it, like pipe got snagged or rubbed thru etc. Even then worst case it might wet the spoil board a little but it's not going to wreck the machine.



The problem with hobby CNC machines using full sized spindles is weight. For example the reason most router based CNCs use router is because of weight either bogging the gantry down or causing the Z-axis to fall (like the Shapeoko, Ox etc). I think the Shapeoko actually used a SPRING at one time to help keep the router from dropping and not being able to get back up again. So a proper spindle is out of the question.

Cannot blame the Tech because people select the wrong motors and underbuild Z-axis. There is also a reason why we tell people to avoid machines like shepeko with this being just one of them.!



I think everyone I know of (bar one who went water cooled and had to go double belt and larger stepper motors before it would stop bogging down) has gone the air cooled spindle route. But if I could afford all metal underside and stronger steppers or drives there would be no question. In that case it would be water cooled all the way.

At the end of the day it all comes down to cost.

No at end of the day it comes down to if machine can handle the spindle or not.! . . . Not just the cost. From what your saying you have Shapeko type machine and the simple truth is these weak machines cannot handle large spindles like these. Got nothing to do with how it's cooled and everything to do with build quality.

Comments like your really piss me off because your actually discouraging people from using products which you clearly have little or no experience of using.

Anyone who's used an Air-cooled spindle then switched to WC spindle will say how much better they are. They also don't slag the Tech because the machine is rubbish.
Just the lower noise alone is enough for most people to switch but the fact the duty cycle is pretty much unlimited and the extra power they offer just blows the cheap Air-cooled spindles away.
Even much higher quality air-cooled spindles like HSD cannot match the cheap WC spindles when it comes to the duty cycle. Cheap air-cooled spindles are limited to just a few hours of constant running at high speeds which is useless to any decent machine. WC spindle will happily run for days at full speed.

[JAZZCNC]

I never considered getting any electronics from China out of fear of bad quality, but I'm starting to consider my position.




Yep, compared to the cheaper Chinese stuff where quality can range from 'OK' to bad. Keep in mind, even stuff that we consider good like 'Panasonic etc' is almost always Chinese.

I've found the secret with buying Chinese electronics is to buy from the manufacturers directly rather than from sellers of general CNC components ie: BST etc (thou I do buy from Fred). This way your dealing directly with someone who knows the settings etc and got Tech's who can help.

I mostly fit Lichuan closed-loop systems now and I can honestly say that I've only had one faulty drive which got damaged due to me oversizing the transformer by mistake. Also Lichuan replaced it FOC knowing it was my fault as a goodwill gesture.

I've probably fitted 50+ sets of motor/drives ranging from NEMA 23 2nm/50Vdc to NEMA 34 12nm/220Vac along with AC servo's ranging from 400w to 2Kw and not one as failed in use.

I'm not saying any of this as an advert for Lichuan, thou I do recommend them. But more to point out that shouldn't fear Chinese products provided you do the due diligence, which is true even in the EU.

Being totally honest I actually get better support, service, and respect from my Chinese suppliers than I do EU suppliers.! For instance, It's Chinese New year and every year for the last 5 yrs, Fred, at BST as sent me Gift of Chinese Tea with a handwritten thank you letter. Which is in stark contrast to other UK/EU suppliers I use in my main business who some of which I spend in excess of 150K a year with and don't even get a Xmas card from.!!

You can save a lot of money if you take the time and shop around.
https://www.aliexpress.com/store/1907567?spm=a2g0o.detail.100005.2.569f5bd5XOOljj

[Kitwn]

I bought my Huan Yang spindle and matching VFD (pre-configured to suit the spindle) as a set from the Huan Yang Shop on AliExpress. Seemed a bit of a no-brainer choosing them as the supplier really. Got here in a few days, which is very impressive considering where 'here' is.

[AndyUK]

For instance, It's Chinese New year and every year for the last 5 yrs, Fred, at BST as sent me Gift of Chinese Tea with a handwritten thank you letter.

Huh. Fred mentioned he was sending me some extra thankyou gift around Chinese New year, but it never turned up. I always wondered what he was talking about... I blame the postie.

[JAZZCNC]

Huh. Fred mentioned he was sending me some extra thankyou gift around Chinese New year, but it never turned up. I always wondered what he was talking about... I blame the postie.

Mine arrived yesterday by Royal mail. It's Chinese Tea(tea leaves in packets) in a decorated tin tea caddy. I got a funny story actually from last year.

Last year he sent something along similar lines but little more novelty wrapped in different shaped packets and selection of tea types. Some of them were wrapped in packets and looked like Faroe Rocher chocolates.! . . . I opened them and threw them on my desk. The phone rang so I answered it just as my mate and colleague walked into the office sat down and greedy fat Git promptly stuffed one in his mouth... I've laughed so much I couldn't speak on the phone his face was a picture..:hysterical:

[NeoMorph]

Sorry I know this is not exactly topic related but I'm not standing by and not saying anything on something which is SO WRONG and will potentialy lead others in wrong direction.



Cannot blame the Tech because people select the wrong motors and underbuild Z-axis. There is also a reason why we tell people to avoid machines like shepeko with this being just one of them.!




No at end of the day it comes down to if machine can handle the spindle or not.! . . . Not just the cost. From what your saying you have Shapeko type machine and the simple truth is these weak machines cannot handle large spindles like these. Got nothing to do with how it's cooled and everything to do with build quality.

Comments like your really piss me off because your actually discouraging people from using products which you clearly have little or no experience of using.


Dude, you shot at the ground and missed.... just like you missed the point of hobby users first CNC who don’t know about engineering and have never put a CNC together before.

I DID POINT OUT THAT ITS THE WEIGHT CAUSES THE GANTRY TO BOG DOWN but you obviously missed that. The water leakage thing was just me pointing out another thing in the con side of the pros and cons list.

Here you go...


The problem with hobby CNC machines using full sized spindles is weight. For example the reason most router based CNCs use router is because of weight either bogging the gantry down or causing the Z-axis to fall (like the Shapeoko, Ox etc). I think the Shapeoko actually used a SPRING at one time to help keep the router from dropping and not being able to get back up again. So a proper spindle is out of the question.


And you are soooo wrong. You knock Shapeoko type machines (I have a heavily modified Ox btw) yet to get anything better COSTS MORE MONEY.

I even said that when I could afford to get a better built machine I would go water cooled spindle because it’s superior tech. Cost me up a Workbee kit and then cost me up a decent heavy gauge gantry alone. I’m 100% sure the decent gantry is going to cost a lot more than the full Workbee kit alone.

Just look at the CNC4newbie ultimate gantry upgrade for a Shapeoko. A 500mm gantry cost $999.

I’m not trying to say I’m an expert on this subject... far from it. But the guys who have been working with CNC for years sometimes forget it’s not so easy starting out when you might be an office worker who wants to dabble in CNC. After all, the OP was going to buy one of those Chinese toys before he realised his mistake.

A Shapeoko or Workbee is a great tool to start out on. Hell, just look a John Saunders. He started out with a tiny mill next to his bed ffs and now look at him. It’s better to crawl before walking (unless you have some engineering, programming and electronics knowledge).

Edit: John Saunders is NYCCNC on YouTube and owns a huge factory (Saunders Machine Works) full of CNC machines. Guy’s a star.

So please read fully before going full “I could make a CNC out of a couple of paper clips and a hairdryer motor that is better than a Shapeoko”. It IS down to money... but also skill, time and learning. But I’d still love a water cooled spindle. I’m making do with a Dewalt 611 and a SuperPID for speed control.

Oh and that weight thing... that is what I was told by SEVERAL CNC suppliers regarding Shapeoko, Workbee and Ox kits when I enquired back in 2015.

[JAZZCNC]

Dude, you shot at the ground and missed.... just like you missed the point of hobby users first CNC who don’t know about engineering and have never put a CNC together before.

I DID POINT OUT THAT ITS THE WEIGHT CAUSES THE GANTRY TO BOG DOWN but you obviously missed that. The water leakage thing was just me pointing out another thing in the con side of the pros and cons list.

No, I didn't miss it and nobody knows better than me how new CNC user/builder struggles because I'm helping them on a daily/weekly basis.
Your comments about WC spindles are wrong on just about every level. Plus the water is only a Con when not fitted correctly just like anything wrongly fitted becomes a Con.!


And you are soooo wrong. You knock Shapeoko type machines (I have a heavily modified Ox btw) yet to get anything better COSTS MORE MONEY.

I even said that when I could afford to get a better built machine I would go water cooled spindle because it’s superior tech. Cost me up a Workbee kit and then cost me up a decent heavy gauge gantry alone. I’m 100% sure the decent gantry is going to cost a lot more than the full Workbee kit alone.

Just look at the CNC4newbie ultimate gantry upgrade for a Shapeoko. A 500mm gantry cost $999.

Oh but I'm not wrong. I've just looked at the Workbee and priced it at nearly £1500 for 500 x 500 cut area using a poxy DeWalt router.
https://ooznest.co.uk/product/workbee-cnc-full-kit/#review

Now throw in any modifications like you have made and it won't take long to reach £2k. And you'll still have a pretty shite machine at the end of it.

Anyone who is prepared to take there time, do some research and possibly learn a few new skills can easily build a much better machine at same size for around that cost.
This machine will have linear rails, not crappy bearings riding on soft metal. Ballscrews not elastic bands for linear motion. Proper Digital drives running decent voltage which steppers need for speed, not crappy drives that can only just handle enough volts to run a light bulb let alone a stepper needed for a real router.
All with proper Z-axis that can handle a real spindle and a Gantry that won't need any upgrading just to cut a piece of wood. And best of all when ready to upgrade to a larger machine they will easily return their investment when they sell it.



A Shapeoko or Workbee is a great tool to start out on. Hell, just look a John Saunders. He started out with a tiny mill next to his bed ffs and now look at him. It’s better to crawl before walking (unless you have some engineering, programming and electronics knowledge).

These machines are a joke as router.! . . . If you want a machine to learn on then buy a cheap Chinese machine for half the costs. They are great learning machines for anyone on a budget, just don't expect the earth or try to upgrade.
If you want a real router then you have to either pay a proper price for the real thing or build your own. Anything in between is usually cheap imitation that will always be inferior and cost more money long term.

I also know John (saunders) very well having communicated with John many many times when he first started out in his New York flat. I've been at this a long time and there aren't many who I haven't dealt with(argued) or helped, or been helped by.!... DIY CNC is a small world with a great community.

My objection to your comments was the rubbishing of the WC spindle and suggesting the fact it's WC is a bad thing when you have no experience of using one. It really pisses me off when this happens because people's unjustified and biased opinions or comments on something they have no experience of using can and does send New builders down the wrong route.
By all means, say they are too heavy for Workbee.shapako, etc but don't rubbish them for being WC and suggest they leak and wreck work, etc when you have no experience of this because it's just not true when fitted correctly.

[NeoMorph]

Your comments about WC spindles are wrong on just about every level..

My objection to your comments was the rubbishing of the WC spindle and suggesting the fact it's WC is a bad thing when you have no experience of using one. It really pisses me off when this happens because people's unjustified and biased opinions or comments on something they have no experience of using can and does send New builders down the wrong route.
By all means, say they are too heavy for Workbee.shapako, etc but don't rubbish them for being WC and suggest they leak and wreck work, etc when you have no experience of this because it's just not true when fitted correctly.

*Facepalm*

You obviously need to learn to read mate. I’m not effing saying that water cooled spindles are rubbish. I’m saying they are AWESOME ON WELL BUILT MACHINES.

I give in. You obviously have the “Haha you have a crappy little CNC” mentality when there are a LOT of us smaller CNC users happily using Shapeoko, Workbees and the like... and making some really nice stuff with them too. You only have to look at people like Winston Moy to see what I mean.

Granted, the smaller CNC won’t work in harder materials than Aluminium but I don’t care as that isn’t what I got mine for.

I’m just making Flight Simulator parts and small wood projects. I’ve not got the cash to buy even a small cast iron based machine and never even will have being disabled and nearly 60 years old.

The bonus features of the smaller machine means I could at least lift it (well, I did have to have help when I rebuilt the carriage with steel reinforcements as I couldn’t lift it onto the frame when I finished - I’m a soddin weakling).

Look, let’s keep this civilised and agree to disagree. Smaller, self build kits have their place in the world. Yes, VMCs they are not, but I have had a lot of enjoyment with mine and I’m still learning something new every day even though it’s bloody hard remembering everything with the morphine and other painkillers I have to take. I’m sorry if I got a bit irritated with you but this time of year is hard on me.

I do agree with you regarding the fact that any spindle is better than a router if your machine can handle it without bogging down.

Easier access to collets, lower runout, and QUIETER are the good points... heavier weight probably requiring larger steppers, larger steppers mean more current so would have to replace the CNC xPro controller for something that could handle it...

But then the stronger steppers mean needing a better framework than v-slot and belts. It would need upping to linear rails and ballscrews... good kit if you can afford it. Then you have to get the uprights made. Not hard, just more expense. Same goes for the rest of the hardware. If you can make it yourself, then great... but a lot of people can’t.

Then there was my worry about leakage from newbie plumbing (for OCD peeps like me) and having to have a big bucket of water to kick over, oh and width of spindle bracket means I would have had to redesign my gantry as it was too narrow... those are the bad points for me and that is why I’m still using my Dewalt router. One change means a domino effect of other changes and in the UK there isn’t that much choice in hobby CNC kit. It’s simpler to get a better machine made... but there’s one problem.... I CANNOT AFFORD IT.

So please don’t disparage us hobby CNCers who cannot build them from scratch. Not everyone is as talented as you JazzCNC.

Oh and reading back the only thing that is shite here is your attitude. You never read what I originally put. Go back and read again... my only problem was with weight WEIGHT, WEEEEEEEEIIIIGHT... from advice from my supplier (Ooznest). I just added the comment about fluid leakage because I’ve seen it happen when building water cooled pcs (and those aren’t moving back and forth). You can’t tell me that leaks never occur. If you do, then you should go work for Trump as he loves liars.

So this is my last post here. I was trying to help but it seems only the god of CNC building, mr JizzCNC should give advice to newbies. Farewell idiot. 🙄

[Juranovich]

No No No I'm most definitely more THE OUT LAW.!!


The pedant in me wants to point out that yes, my radiators are air-cooled. They're also water-heated!

Could it be that... AndyUK IS THE LAW.!! ??

[Juranovich]

So this is my last post here. I was trying to help but it seems only the god of CNC building, mr JizzCNC should give advice to newbies. Farewell idiot. ��

I'm not jumping on the who-did-or-said-what train, but I will say that I appreciate all the advise I can get. Different perspectives only make my understanding deeper. As a beginner my main mental hurdle is to differentiate between the theoretical and practical side of things (which often don't go hand in hand). Naturally, I can only find out my capabilities by actually taking the plunge, but before I do that I do want (at least try) to make my plans as doable as possible, considering my level of competence. To this end, hearing different perspectives only helps me better understand all the pitfalls I might be up against. In the end I'd rather have a well built, but less advanced machine than a poorly assembled, but in theory top tier machine...

[NeoMorph]

I'm not jumping on the who-did-or-said-what train, but I will say that I appreciate all the advise I can get. Different perspectives only make my understanding deeper. As a beginner my main mental hurdle is to differentiate between the theoretical and practical side of things (which often don't go hand in hand). Naturally, I can only find out my capabilities by actually taking the plunge, but before I do that I do want (at least try) to make my plans as doable as possible, considering my level of competence. To this end, hearing different perspectives only helps me better understand all the pitfalls I might be up against. In the end I'd rather have a well built, but less advanced machine than a poorly assembled, but in theory top tier machine...

I’m sorry for my rather irritable last post. I was having a bad night due to pain when I came across JazzCNC’s attacking reply.

I can’t understand elitist advice who say that because I have never used a product that I cannot pass on advice I was given when I was shopping for a 2.2kw water cooled spindle for my machine.

I spent several months deliberating. I wanted a quieter setup you see.

But time after time I got the advice that while a water cooled spindle was great that an air cooled one would be better for my setup. Less hassle, less weight. It’s also the reason that last summer I rebuilt my gantry with heavier gauge uprights to support a spindle.

Jazz is 100% right that a good design with a heavier gauge setup is great and all but getting one is going to cost a lot more money. But calling the smaller machines shite and then praising the tiny eBay machines is bonkers.

If you can afford it, get a heavier gauge gantry with linear bearings and digital drives like Jazz says. Then a water cooled spindle is a no brainier. But that means a more expensive control setup. It means purchasing Mach 3 or 4. More money. Paying to have custom plates made. Yup, more money. It can get expensive fast.

What many here missed was that your original post said you want your machine to work with wood. Someone disparaged a belt driven design and Jazz actually shot them down saying don’t knock it until you try it and then yesterday he said my machine is crap because it’s driven by elastic bands lol.

Every design has pros and cons. I would love a good quality built machine but you have to be precise in building it or it ends up outputting inaccurate parts. The stiffer the build, the more accurate it will be... but the more dense it is, the heavier it is and you get sagging. Not a lot but engineers fret about parts of a millimetre.

So that’s where the aluminium extrusion system came in. Lighter beams, using a router instead of a dedicated spindle, lighter general stepper motors, grbl instead of mach3... yet still the machine can cut wood projects fine. I’ve been cutting 18mm thick plywood quite nicely on my “shite” machine.

My machine is 1.5m x 1m and it works great for what I use it for. I’ve actually fixed a few of the base machine faults (like no limit homing switches, double belting to make it closer to a rack and pinion than a belt drive, stiffened up the gantry and used a heavier gauge Z axis... oh and the SuperPID turns the router into a poor mans spindle by giving you computer control of the spindle speed and on/off) but I really wish that the original design thought more about maintenance.

I wish I could afford the things Jazz mentions but realise it’s not something I can afford and in the meantime I’m already cutting parts that are near enough perfect.

[Juranovich]

I bought my Huan Yang spindle and matching VFD (pre-configured to suit the spindle) as a set from the Huan Yang Shop on AliExpress. Seemed a bit of a no-brainer choosing them as the supplier really. Got here in a few days, which is very impressive considering where 'here' is.

I out curiosity, in which regard do you see it to be a no-brainer? Have you been pleased with it?

[Juranovich]

I wish I could afford the things Jazz mentions but realise it’s not something I can afford and in the meantime I’m already cutting parts that are near enough perfect.

I think this sums it up quite well, I'm now at that stage where (I think) I've got the design for "my perfect machine" figured out and am now shopping around for prices. Once I know what my ideal machine will cost I'll have to decide whether it's worth it or if I'll have to start toning it down. This is where the different perspectives come in, they help greatly in understanding the trade-offs of what the possible "downgradings" of components would mean in practice. At the end of the day, I reckon all of us strive to have the best machine possible given our personal constraints (time/capability/money etc.). What's great about this forum is that I seem to be getting good advice from people with actual personal experience from whatever set-up they're using. This is what I find most valuable since it allows me to make an informed choice on where to spend my euros and also to set my expectations accordingly.

While I naturally don't like to see anyone being offended, as a novice bystander, it must be said, I still pick out good insights from the sometimes unnecessarily heated debates. As always, it's up to the one looking for advice/reading the forum to decipher the value of the information being conveyed. All in all, I'm grateful for both your and JAZZ's inputs, as I am for everyone else's who's contributed to this thread and elsewhere!

NB! Hope my reply didn't sound too much of an politician's reply, it so just happens to be how I feel about things...now I'll get back to shopping around!

[JAZZCNC]

Look, let’s keep this civilised and agree to disagree.

I was happy to do that then you went and put this.!. .. Seriously.!!


So this is my last post here. I was trying to help but it seems only the god of CNC building, mr JizzCNC should give advice to newbies. Farewell idiot. 🙄

Obviously your Meds haven't kicked in and guess what your not the only one on here who is disabled or in bad health so cut the poor me crap.!

I have helped many disadvantaged people on this forum and others, ranging from low incomes through, disabled, depressed to Terminally Ill build very nice machines on low incomes. Several are no longer with us but I can tell you this none of them Bitched as you have about being disabled or on a low income, they had more self-respect.!

I didn't personally insult you, so please don't do that to me.

I would also like it if you stayed on the Forum because then you might see that what I say or comment on is not for Ego or Dick slapping purposes but rather for the sake of others who do not have the time to read lots of posts or trawl the internet all day.
What they do is read snippets and see comments like yours that are either just plain wrong or poorly explained and then buy or act upon them. This is not my opinion it's a fact I know because many of them end up asking me for advise or help after they have wasted money and time.

My opinion of these OZnest type machines as nothing to do with machine snobbery and everything to do with the fact my opinion is they are poor quality, poorly designed low spec machines that are overpriced which can be beaten hands down for similar costs if you DIY build. Just because you or others take offense to me saying it doesn't mean I'll stop.
Only those who have had one and then DIY built one can fully appreciate what I'm saying and only when you have experience of both sides can you truly comment and it means anything. That goes for anything, spindles, drives, etc otherwise it's always a biased opinion.!! My opinions are never one-sided and always given from personal experience of all sides.

So please stay on the forum and give your valuable opinions. All I ask is you just don't advise people or knock stuff on which you have no experience of using because I will always jump on it for the sake of others.

Now if I've upset you please accept my apology and know that none of what I've said was a personal attack on you.

I won't be posting again on this matter here so for the sake of the OP just leave it now or send me a PM if you want to continue with the insults.

[NeoMorph]

Jazz, I wasn’t saying about the disability as a poor me... I was explaining it as a a barrier to me building heavier machines AND retaining info due to the meds. I have to have a carrier bag full of meds every month and that’s why I had to give up working... hence lack of cash. Hell, I once dislocated my thumb playing COD4. 😂

For example you once put that £45 wasn’t much for a stepper motor driver. Multiply by 3 and then add in the new steppers. Then there is the psu. All this costs.

But unless I can build the mechanicals strong enough handle the extra whoomph then it’s wasted money. Why buy a rally car just to go to the shops. Still doesn’t stop me WANTING that rally car though.

Regarding mood of my previous post... I was trying to calm it down from your bitchy posts when I reread that you think Shapeoko and Ox machines are “shite”... and it just triggered me... sorry. Winter sucks for me tbh. Being stuck in bed does that.

So Jazz, sorry for my side of things. If you actually read back through this thread I was 100% agreeing with you before you went off at me. I’d rather be friendly than combative. Doesn’t mean I won’t bite back if you malign what I say though. 😉

Peace?

[JAZZCNC]

Hi,

Just to hopefully clear the air and clear any misunderstandings.


Jazz is 100% right that a good design with a heavier gauge setup is great and all but getting one is going to cost a lot more money. But calling the smaller machines shite and then praising the tiny eBay machines is bonkers.

The point of being £350 is better than £1500 for learning on. Great to test the waters and then pass on when ready for a better, bigger machine.


If you can afford it, get a heavier gauge gantry with linear bearings and digital drives like Jazz says. Then a water cooled spindle is a no brainier. But that means a more expensive control setup. It means purchasing Mach 3 or 4. More money. Paying to have custom plates made. Yup, more money. It can get expensive fast.

It doesn't need to get expensive, doesn't need Mach3 either plenty of free controllers, Linux CNC, for instance, is as good if not better and free.
Yes for someone who's disabled I understand it's more difficult but it's still do-able.
The profile is more than good enough for a great machine, it's what you hang off it that matters. This is where the Workbee etc fails badly. Linear rails and ballscrews are not that expensive from China, neither are the electronics when you shop around. It's just about doable with £1500 easier with £2k, I've helped several people who have limited means or ability's for whatever reasons build great machines under £2k.


What many here missed was that your original post said you want your machine to work with wood. Someone disparaged a belt driven design and Jazz actually shot them down saying don’t knock it until you try it and then yesterday he said my machine is crap because it’s driven by elastic bands lol.

That reference was to the size of the belt not the fact it's belt-driven. Not all belts are suitable.!


Every design has pros and cons. I would love a good quality built machine but you have to be precise in building it or it ends up outputting inaccurate parts. The stiffer the build, the more accurate it will be... but the more dense it is, the heavier it is and you get sagging. Not a lot but engineers fret about parts of a millimetre.

So that’s where the aluminum extrusion system came in. Lighter beams, using a router instead of a dedicated spindle, lighter general stepper motors, grbl instead of mach3... yet still the machine can cut wood projects fine. I’ve been cutting 18mm thick plywood quite nicely on my “shite” machine.

This my point, it doesn't need to be massively built to cut good parts that are accurate. It just needs to be built with better design and components that don't limit or cripple performance. Just because something cuts a material doesn't mean it's good at it. A properly built machine will cut it faster and more accurately with a better finish quality and that doesn't need to cost the earth to do that.

Just remember when your getting advice from the supplier or manufacturer you are often getting a biased opinion which is nearly always given with there own interests or protection in mind.!

Again my comments were not an attack on you personally and if you took them that way then I'm very sorry, it wasn't my intent.

Dean.

[NeoMorph]

Jazz... Dean, I’m John btw... crisis over. Please ignore if I rant middle of the night (meds... literally can’t help it)

Okay I have to say I’m intrigued now. I wonder how much it would cost to change a belt driven Ox to a machine that could run on linear rails.

My gantry used to be 750mm of 2x 8020. I bolted them together to make it stiffer. The two frame rails that the gantry runs on is a single 1m 8020 each side with more 8020’s at either end. The two gantry plates are taller than normal Ox plates and are made of steel.

What do you think it would take to switch to linear rails with ballscrews, including plates cut to mount the ballscrews and gantry carriage plates (I’m guessing those would need replacing).

Add in digital drivers and replacement steppers and psu. My current steppers are Motech MT-2303hs280aw 175oz 2.8a ones. THEN add in the spindle and VFD. I looked up and found my CNC xPro controller can handle external controllers so I can get away with using that.

[NeoMorph]

This is my deformed Ox btw. Strange coincidence is that I only just found out that I was born in the year of the Ox in the Chinese calendar... and I ended up buying an Ox CNC machine. Go figure.

27202

[JAZZCNC]

Jazz... Dean, I’m John btw... crisis over. Please ignore if I rant middle of the night (meds... literally can’t help it)

Okay I have to say I’m intrigued now. I wonder how much it would cost to change a belt driven Ox to a machine that could run on linear rails.

My gantry used to be 750mm of 2x 8020. I bolted them together to make it stiffer. The two frame rails that the gantry runs on is a single 1m 8020 each side with more 8020’s at either end. The two gantry plates are taller than normal Ox plates and are made of steel.

What do you think it would take to switch to linear rails with ballscrews, including plates cut to mount the ballscrews and gantry carriage plates (I’m guessing those would need replacing).

Add in digital drivers and replacement steppers and psu. My current steppers are Motech MT-2303hs280aw 175oz 2.8a ones. THEN add in the spindle and VFD. I looked up and found my CNC xPro controller can handle external controllers so I can get away with using that.

Not fair to the OP to continue this here so start a thread if you want to persue this more and I'll comment on it.

[NeoMorph]

Hmmm okay. I did think it would assist in design theory for a new machine that improves on a a base “hobby” CNC build which is why I put it here.

[NeoMorph]

I’ve started up a new thread at http://www.mycncuk.com/threads/13355-How-Would-You-Upgrade-An-Old-Ox-CNC-Build-Into-A-Serious-Machine

My apologies to the OP for hijacking the thread. I should know better being an ex admin. ��

Here is one really good idea that has saved me a lot of time. Get a small A5 hardback notebook and any ideas, changes, wiring diagrams and the like so you have a physical record of what you’ve done to your machine. It’s surprising how convoluted the wiring can get as there is the mains to psu... psu to the controller board... controller to three steppers... controller to SIX limit switches... controller to VFD... controller to coolant (or in my case vacuum... controller to hardware buttons including such as emergency stop, start program, pause and more if you do choose... and finally mains to VFD and vacuum (or water pump if you use cooling.

Yup... it all adds up. So if you log and label all the wiring it is easy to track down faults That may occur and an A5 sized notebook makes it easy to hold in one hand while tracking problems and tracing wires. It it also convenient to store with your machine without getting in the way.

Here is something funny. I was just checking the forum notifications when I saw one from 2017... this shows how much a noob I am at CNC stuff... I didn’t have a clue back then, let alone a machine at that point.

http://www.mycncuk.com/threads/11063-Totally-Green-CNC-Oldie-Needs-A-Start-Point

[Kitwn]

I out curiosity, in which regard do you see it to be a no-brainer? Have you been pleased with it?

My past reading about which spindle to choose suggested that Huan Yang was a well used and reliable manufacturer of the most popular 2.2KW water-cooled design but that there were plenty of less reliable copies available from other suppliers, especially with regard to the VFD. This is why I decided that buying a combined set of spindle and matching VFD direct from that manufacturer's own shop was the obvious choice.
I have been very pleased with the spindle and VFD so far, it has worked perfectly and the majority of the VFD settings were factory set to the recommended values I found on this forum.

[NeoMorph]

My past reading about which spindle to choose suggested that Huan Yang was a well used and reliable manufacturer of the most popular 2.2KW water-cooled design but that there were plenty of less reliable copies available from other suppliers, especially with regard to the VFD. This is why I decided that buying a combined set of spindle and matching VFD direct from that manufacturer's own shop was the obvious choice.
I have been very pleased with the spindle and VFD so far, it has worked perfectly and the majority of the VFD settings were factory set to the recommended values I found on this forum.

Hmmm, I’ve taken a leap of faith and ordered a set for myself. Recently got a surprise rebate from my energy company (their automated system had increased my monthly payments and had built up a big surplus) so I think I’ll start getting parts for my second machine (that’s if I can update my first one). Will be interesting to try out.

[Kitwn]

Hmmm, I’ve taken a leap of faith and ordered a set for myself. Recently got a surprise rebate from my energy company (their automated system had increased my monthly payments and had built up a big surplus) so I think I’ll start getting parts for my second machine (that’s if I can update my first one). Will be interesting to try out.

I hope you are not disappointed!
One thing to be very careful of is the quality of your soldering inside the 4 pin plug to the spindle. If soldering is not one of your strong points, practice until it is :welcoming:

The power transistors in VFDs and stepper drivers are not very tolerant of sudden disconnections or short circuits to earth and many of the sob-stories you read about VFDs that failed early may be due to poor installation rather than a bad product.

Good soldering depends on cleanliness, a one molecule thick layer of grease from your fingers is enough to make the difference. Flux is also important. If the solder is forming blobs rather than flowing freely over the wires and pins then you have a problem. The old saying 'The bigger the blob, the better the job' is NOT good advice. Sleeving on each pin inside the plug is also a good idea and, as others have mentioned recently, a cable clamp on the Z axis assembly to stop the cable moving as it enters the plug is essential. I assume YouTube has a choice of videos on how to solder.

Sorry if I'm preaching to the converted and your soldering is exemplary, but I'm sure we have plenty of readers who buy their first soldering iron specifically to install a spindle and an expensive VFD is not the best device to learn on.

[Juranovich]

My past reading about which spindle to choose suggested that Huan Yang was a well used and reliable manufacturer of the most popular 2.2KW water-cooled design but that there were plenty of less reliable copies available from other suppliers, especially with regard to the VFD. This is why I decided that buying a combined set of spindle and matching VFD direct from that manufacturer's own shop was the obvious choice.
I have been very pleased with the spindle and VFD so far, it has worked perfectly and the majority of the VFD settings were factory set to the recommended values I found on this forum.

Fair enough! It seems to be the go-to set-up at that price point. Although, in all fairness, I can't seem to find any alternatives either (other than units looking exactly the same, but with different logo)...How do you find the noise level? In youtube videos it seems a bit noisy, especially the VFD.

[NeoMorph]

I hope you are not disappointed!
One thing to be very careful of is the quality of your soldering inside the 4 pin plug to the spindle. If soldering is not one of your strong points, practice until it is :welcoming:

No probs on the soldering side of things. I have a full on micro soldering setup at home along with microscope and various electronics kit. I like to repair any of my tech at home as I am actually qualified in electronics test and service mechanics and have a City and Guilds certificate too.

If you think soldering is hard try hand soldering an 0203 component under a stereo microscope. Even a bit of static will lift the component if you are not careful. I’ve gently touched the board with the flux syringe before now and had the resistor, or whatever, just vanish.

I also made an emergency stop interface for my CNC. I can watch my machine from another room on my iPad and if something goes wrong I just say Computer SCRAM and it hits the emergency stop on the machine from wherever I am in the flat. It’s actually safer than the amount of time it would take to reach my machine on crutches and I’m not sitting in front of a noisy machine for 1hour plus when it’s doing 3D carving of curved surfaces.

So yeah... soldering is a good skill to have.

[Kitwn]

neoMorph,
I've made a few DIY surface-mount circuit boards but 1206 is my stock size for resistors and 0.05" pitch for chips so I'm sticking Stone Henge monoliths together by your standards.

[Neale]

As far as noise is concerned, the VFD has a fan which is noticeable in my workshop but not intrusive. The actual spindle is quiet enough that I'm happy to stand next to it when it's running. However, once it starts cutting then the noise makes me put on ear defenders!

[NeoMorph]

neoMorph,
I've made a few DIY surface-mount circuit boards but 1206 is my stock size for resistors and 0.05" pitch for chips so I'm sticking Stone Henge monoliths together by your standards.

It’s easy enough to solder 0603 with practice but I prefer to stick to 0805. I tend to buy my surface mount parts in sample books and top up when I use them. Helps keep track of the tiny suckers lol.

Regarding the plug, if it’s the type I think then I already have several in my current CNC build. Even have some 7 pin ones. Those are hard.

Is it these ones?

27215

[JAZZCNC]

Is it these ones?

27215

Similair just larger and bit more HD.

[NeoMorph]

I always have difficulty judging sizes from pictures. Usually have to get my callipers out.

[Doddy]

but 1206 is my stock size for resistors

You could row all the way to Aus on a 1206! :drunk:

0603, less than that and you're just being a masochist.

[AndyUK]

I always have difficulty judging sizes from pictures. Usually have to get my callipers out.

They look like GX16?

The spindle will take a GX20.

I've been soldering lots of 7-pin GX16s and 4-pin GX20s this weekend.

Tip number 1: Get someone to help hold stuff. Failing that, grab a vise or something. And like ten of those helping hands things.
My technique (who knows if its good, but it seems to work). Tin the wires. Prep the pin with a decent amount of solder. Then flow it whilst simultaneously heating the wire, and bring the two together asap. Reflow once you're happy its in a good place to avoid a cold joint. Can be a real PITA when you're dealing with very short cable ends to keep it looking tidy.

Oh and DON'T forget to put everything on the right side of the damn panel. Spot the error below...

2721627217

[Kitwn]

They look like GX16?

The spindle will take a GX20.

I've been soldering lots of 7-pin GX16s and 4-pin GX20s this weekend.

Tip number 1: Get someone to help hold stuff. Failing that, grab a vise or something. And like ten of those helping hands things.
My technique (who knows if its good, but it seems to work). Tin the wires. Prep the pin with a decent amount of solder. Then flow it whilst simultaneously heating the wire, and bring the two together asap. Reflow once you're happy its in a good place to avoid a cold joint. Can be a real PITA when you're dealing with very short cable ends to keep it looking tidy.



The vice is a must. If you put a socket (plug) in the vice and plug in the plug (socket) you're soldering then the socket (plug) will support the pins in place and help avoid distortion through overheating the plastic, though if you're as quick as you should be this won't be a problem. You're using the same method I do, just keep everything clean before tinning, don't twist the wires with sweaty fingers and clean the iron on a sponge between each application. Don't try using a gob of solder that's been sitting on the iron for a while. Sleeving over each pin will prevent shorts between pins or pins and the case.

[NeoMorph]

I’ve got half a dozen or so helping hands that I use. Some are missing arms, some have been modded with mounts for plugs to be held without distortion. I usually make them out of wood as it doesn’t transfer the heat into the plastic that way.

Same goes for PCB holders. I used to lust after a decent pana-vice but they are crazy expensive for what they are. If you are any good at putting together a CNC then you could make a better one.

[Juranovich]

Hi again, I've been somewhat occupied with work lately, hence, the radio silence. I've got offers on nearly all main components and the intended design seems to be within budget. One loose end is the aluminium plates which I'll have to have made for me and to that end I wanted to ask a practical question (as I have very limited experience working with metals); what tolerances do you use on screw holes? More specifically, I'll probably end up using a combination of M5, M6 and M12 screws and 20mm aluminium plates.

[Doddy]

I think you probably mean clearance hole size rather than tolerance? Google "metric clearance hole chart"

Edit: Or if I've misunderstood then ignore the above.

[Juranovich]

I think you probably mean clearance hole size rather than tolerance? Google "metric clearance hole chart"

Edit: Or if I've misunderstood then ignore the above.

Precisely, tolerance, not clearance. And just for the record (and before anyone posts a lmgtfy-link :) ), I did try to google it before asking on here but using highly scientific terms like "screw hole sizes" did not yield me any useful info. Anyway cheers, I got exactly what I needed!

[NeoMorph]

I think Juranovich meant tolerance of holes being in the right location.

I’ve seen makers use the rails with hole transfer punches to make sure the holes are in the right place. Put the rail on the plate, loosely clamp down one end and then measure and tap to the right distance from the edge. Do the other end the same and then go back and forth until both end are perfectly aligned before clamping down hard... then one final measure to make sure the rail hasn’t moved.

Then if that is all correct, just go down the holes with the correct size hole punch and tap in the locations for the holes. Follow up with a drill press or a mag drill (you can even rent them according to my friend) and Bobbie’s your auntie.

This way, you won’t measure the hole spacing wrong and drop a hole out of position that would knock out the following holes too. Simples, as a certain Meercat would say.

[Juranovich]

I think Juranovich meant tolerance of holes being in the right location.

I actually meant tolerance as Doddy pointed out, but what you describe is also something I'd probably had come back to ask at some point :)

[Juranovich]

As I'm trying to get the whole picture I've had to dip into the electronic side of things. Now I've got offers for steppers, drives and torodial transformers, but I'm a bit unsure on how to size them properly, or specifically how to size the PSU. The specs are as follows:

- NEMA 24 closed loop steppers at 4.5Nm holding torque, 5A, 0.75ohms, 2.4mH (all phase values).
- Drives rated at 20-70VAC or 30-100VDC, 8A peak.
- 420W torodial transformer 220 to 70 VAC, 6 A

Firstly, as the drives can take AC, is there any need to convert the output current from the torodial transformer to DC? As I've understood in case I go for AC to AC I could simply connect the first winding to the mains (with fuse for safety) and the second directly to the drives? Also, assuming no DC conversion, is it safe to use a 70VAC rated torodial transformer to power the drives rated at max 70VAC?

Now, if I've understood correctly the total amps my 4 steppers will draw is roughly 2/3 of the sum of the rated amps of the steppers, i.e. 4*5A*2/3=13,33A. So the PSU would have to supply (rounded up) at least 14A? As the torodial transformer is rated at only 6A, should I consider wiring several in parallel to get more amps or would it be better to simply look for a beefier one to supply all the current i need?

And so the voltage. This has me the most confused, some recommend to not over do the voltage for fear of getting components burnt, while others prefer higher voltages in order to not lose out on max performance (however, in these cases drives usually have some sort of voltage regulators). Now, if I've done the math correctly the Vmax of my parallel wired steppers is 32*√(2.4mH) = 49.6V., so well within the 70VAC outputted by the torodial transformer so as to get the most out of the steppers, BUT (and see first question above) would I run the risk of overheating my drives/steppers with this setup? The drives I've been offered (Lichuan LCDA86H) do list "overvoltage protection", but this sounds to me more like a fuse type protection than active voltage regulation.

[AndyUK]

Firstly, as the drives can take AC, is there any need to convert the output current from the torodial transformer to DC? As I've understood in case I go for AC to AC I could simply connect the first winding to the mains (with fuse for safety) and the second directly to the drives? Also, assuming no DC conversion, is it safe to use a 70VAC rated torodial transformer to power the drives rated at max 70VAC?

If the drives take AC, don't bother rectifying it into DC. Go straight from the transformer to the drives. Don't daisy chain them though. Size the transformer by taking the max motor current (e.g. 4A) times the number of motors (3 or 4), so lets say 12A, then reducing by 1/3rd, so 8A. Don't go too overboard on the VA of the transformer, get what you need. Bigger transformers can suffer from large amounts of inrush current which can trip the power and just be a pain without other compensation.



Now, if I've understood correctly the total amps my 4 steppers will draw is roughly 2/3 of the sum of the rated amps of the steppers, i.e. 4*5A*2/3=13,33A. So the PSU would have to supply (rounded up) at least 14A? As the torodial transformer is rated at only 6A, should I consider wiring several in parallel to get more amps or would it be better to simply look for a beefier one to supply all the current i need?

Well clearly I should have read ahead because you already know the method. Oh well, not editing it now. No just get a larger VA transformer. You probably need 1000VA based on your 13.3A current, but that seems a little high? Most of us have 500-600VA transformers when turning into DC, perhaps someone can shed more light on this.



And so the voltage. This has me the most confused, some recommend to not over do the voltage for fear of getting components burnt, while others prefer higher voltages in order to not lose out on max performance (however, in these cases drives usually have some sort of voltage regulators). Now, if I've done the math correctly the Vmax of my parallel wired steppers is 32*√(2.4mH) = 49.6V., so well within the 70VAC outputted by the torodial transformer so as to get the most out of the steppers, BUT (and see first question above) would I run the risk of overheating my drives/steppers with this setup? The drives I've been offered (Lichuan LCDA86H) do list "overvoltage protection", but this sounds to me more like a fuse type protection than active voltage regulation.

I think most people tend to ignore Vmax and just give them as much as the drivers can manage, then limit the current on the drives so they don't burn. Typically with 3.2mH motors with a Vmax around 58V people use 68V (convenient toroidals are available). Basically I think you want the motors to be warm but not burny hot (demagnetisation occurs when they hit a certain temp).

The overvoltage protection you talk about is interesting though - what do the drives spec for the voltage?

[NeoMorph]

What AndyUK said about larger transformers tending to pop breakers and blow fuses due to high inrush current is right. The less is said about the time I was working on a DIY boost converter for my electronics course, and blew out the power to an entire wing of the YMCA I was living in, the better. That was back in mid 86 so they might have forgiven me now lol.

That was down to high inrush current as well.

But the good news is inrush current can be reduced pretty easily. See here...

http://www.ti.com/lit/an/slva670a/slva670a.pdf

[Juranovich]

Well clearly I should have read ahead because you already know the method. Oh well, not editing it now. No just get a larger VA transformer. You probably need 1000VA based on your 13.3A current, but that seems a little high? Most of us have 500-600VA transformers when turning into DC, perhaps someone can shed more light on this.


Yes! Pretty please! The problem seems to be (assuming 1000VA is an issue- as I'm quite unqualified to judge) that 4-4.5nm steppers seem to be rated at 4-5A and with 4pcs that quickly adds up.



I think most people tend to ignore Vmax and just give them as much as the drivers can manage, then limit the current on the drives so they don't burn. Typically with 3.2mH motors with a Vmax around 58V people use 68V (convenient toroidals are available). Basically I think you want the motors to be warm but not burny hot (demagnetisation occurs when they hit a certain temp).

The overvoltage protection you talk about is interesting though - what do the drives spec for the voltage?

For the record it also lists overcurrent protection. If you're after the input rating it's 20-70VAC and 30-100VDC. Is that what you were looking for?

When your're saying to max the voltage, shouldn't there be some room for the transformer to fluctuate (upwards) from the rated voltage? In this case the transformer outputs 70V which is also the max of the drives. Also regarding overheating, is it the wattage/VA that is the decisive factor or can voltage alone cause over heating? I'm thinking if higher than rated voltage is passed through a circuit but at lower than rated current (i.e. less than rated watts are being fed), shouldn't there then be "unused" resistance in the circuit to avoid overheating? If so, is higher than rated voltage more a question of the structural integrity of the circuit? Or does it maybe manifest in the same way in the end, i.e. burning components...? In the current case the transformer outputs 70V at 6A = 420VA and the drivers can take 70V at 8Apeak = 560VA. Even if I had 4 transformers in parallel and 4 drives in parallel, respectively, the total wattage would still not exceed that of the drives' capabilities. So getting back to what you said about maxing voltage and limiting current, as the drives can take more current than the transformer outputs, I should be on the safe side?

sorry, for the ramblings, my thinking hat came on while writing this...also b/c curious! :excitement:

[Clive S]

For the record it also lists overcurrent protection. If you're after the input rating it's 20-70VAC and 30-100VDC. Is that what you were looking for?


If you are just going to put AC in then I would not go more that 60V AC as the mains can and does fluctuate.

[NeoMorph]

If you are just going to put AC in then I would not go more that 60V AC as the mains can and does fluctuate.

This ^^^^^

Mains electricity is very “dirty” in some areas. Stick a scope on the mains and you would be shocked to see how bad it is at times. It’s the reason if it was me I would at least have a voltage regulator in the circuit at the very minimum. Cleans up that dirty power a treat.

[JAZZCNC]

would I run the risk of overheating my drives/steppers with this setup? The drives I've been offered (Lichuan LCDA86H) do list "overvoltage protection", but this sounds to me more like a fuse type protection than active voltage regulation.

Do not rely on the OV protection of these drives, they will not save you from more than just a few volts. So if you get a spike then they will fry them.
They are good drives provided you leave a good safety margin.

You need to leave at least a 10% safety margin on the voltage and I wouldn't run much above 60Vac with 70Vac Max.

Regards the Transformer I use 750Va with these drives without any issues. I wouldn't go above 750Va because you will get troubles from inrush.

Do NOT use a regulated PSU like as been suggested by one member as it could cause you troubles with voltage clamping.

[NeoMorph]

I keep meaning to ask, do you guys use surge protection or, better yet , run it through a UPS to clean the mains transients from glitching out the machine and computer. I’m wondering if a domestic surge protection device would freak out. I seem to have this memory of a computer with a beast of a psu that kept freaking out because of the surge protector (think it was 1200w psu because of all the extra stuff he was using including a crazy raid array and loads of RGB). Once he ditched the surge protection the machine worked fine.

That’s why I’m thinking a decent UPS would at least let you shut down safely. Or is my OCD going overboard again?

[Clive S]

This ^^^^^

Mains electricity is very “dirty” in some areas. Stick a scope on the mains and you would be shocked to see how bad it is at times. It’s the reason if it was me I would at least have a voltage regulator in the circuit at the very minimum. Cleans up that dirty power a treat.

What are you on about:beguiled: You can supply a drive with a toroidal, rectifier and some caps ie DC or just use a toroidal and use the rectifier and caps in the drive.


That’s why I’m thinking a decent UPS would at least let you shut down safely. Or is my OCD going overboard again?


I think you are going overboard a bit here and frightening new users into things they just don't need:jaded:

[Neale]

The fact that the drives are rated at "20V-70V" AC in is a pretty clear indication that they are very tolerant of input voltage variations. The only thing that really worries them is input overvoltage, which is why Jazz has suggested aiming at about 10% under the nominal maximum to give a bit of headroom for the odd spike, mains surge, etc. There is no point in cleaning up the raw AC input to the drives. These devices are power switching to motors, not audio amplifiers! I hung a 'scope off the DC supply to my drivers some time ago and saw something like a 10V 100Hz ripple across the smoothing caps and the drivers clearly weren't worried about that - they've been working for a few years now quite happily. There are things that need close attention, like good earthing techniques, keeping noise-producing high power cables away from low-level sensitive feeds to inputs, but the basic supply to the drivers can be pretty crude by comparison. In fact, a simple linear power supply will beat the pants off a switched-mode supply when it comes to feeding stepper drivers as you have to drastically over-spec the SMPS to cope with the odd peak load which causes it to go into shutdown or some other protective mode where the linear supply just dips a bit and carries on.

[NeoMorph]

What are you on about:beguiled: You can supply a drive with a toroidal, rectifier and some caps ie DC or just use a toroidal and use the rectifier and caps in the drive.



I think you are going overboard a bit here and frightening new users into things they just don't need:jaded:

No no no, I’m asking the question of experienced users. I’ve only got experience of an openbuilds machine at present and haven’t had the pleasure of building a larger CNC so the op’s question and your reply about mains fluctuations made me think about running tests on the local power grid.

I can’t remember the figures from my last test but I do have the kit still.

I still remember the time back in Cannock where I was sitting in offices and suddenly the ceiling fans turned into scary propellers. Turned out the distribution centre had supplied twice the rated frequency for a while... blew a ton of mainframe terminals throughout the building and only the fact that it tripped the generators protected the two mainframes we had downstairs (IBM 370/158 and IBM 3033).

That truly is a worst case scenario but check your local power. Mine is ruddy awful at times, especially around 6pm. My oven is flashing the clock timer at me because we had a brownout yesterday.

But ultimately I don’t know much about mains system and I haven’t touched anything 3 phase or high voltage this millennium... so I’m very much the noob asking questions.

[NeoMorph]

From what Neale said made me do a facepalm... not at him, at me. Of course the driver will clean it up. I’m a moron.


Sent from my iPhone using Tapatalk

[JAZZCNC]

but the basic supply to the drivers can be pretty crude by comparison. In fact, a simple linear power supply will beat the pants off a switched-mode supply when it comes to feeding stepper drivers as you have to drastically over-spec the SMPS to cope with the odd peak load which causes it to go into shutdown or some other protective mode where the linear supply just dips a bit and carries on.

Neale is 100% spot on and using an SMPS is asking for trouble because at some point it will bite you when it goes into protection mode. KISS works for CNC no need for over complicating the job with Surge protectors or UPS, DHL, FedEx or any other courier service...:hysterical:

Now back to these drives and the Question of AC or DC. I've used these drives with both AC & DC and in terms of performance, I've seen no differences.
However, I've never run them on machines working in harsh conditions regards power fluctuations, etc but I suspect that if the mains supply was prone to fluctuations or was a little dirty then using a DC supply would be less stressful on the drives due to larger Caps being more capable of smoothing out the power than the little caps that will be used on the individual drives.

Now I'm not into electronics so I don't know if when using a DC supply the drives still use their onboard Caps as extra smoothing.? . . my gut says they probably do.!

But that said I would always go with the simple approach if normal conditions so AC is easier and cheaper. The machine doesn't care if you run it on Everyready battery's so long as it gets a nice supply of power when it asks for it.

[Kitwn]

Now I'm not into electronics so I don't know if when using a DC supply the drives still use their onboard Caps as extra smoothing.? . . my gut says they probably do.!
If they use the same input connections for DC as AC as I assume they do then the rectifier and capacitors must still be in the circuit.

One other thing to consider: If you add an additional rectifier and capacitors to make a DC supply for an AC driver you will also increase the inrush current to the transformer and increase the risk of trips. Adding more capacitance for the sake of it to any DC supply (making Neale's audio amp PSU instead of a motor driver one) will have the same effect.

[NeoMorph]

If they use the same input connections for DC as AC as I assume they do then the rectifier and capacitors must still be in the circuit.

One other thing to consider: If you add an additional rectifier and capacitors to make a DC supply for an AC driver you will also increase the inrush current to the transformer and increase the risk of trips. Adding more capacitance for the sake of it to any DC supply (making Neale's audio amp PSU instead of a motor driver one) will have the same effect.

Yup. My brain was in full “doped up on morphine mode”... which is why I did a facepalm. It’s the reason I had to quit work. Not asking for sympathy, just stating the way things are. I seriously do not know this tech, BUT I WANT TO LEARN. It’s better to ask questions and act a fool than profess to be an expert and tell people incorrect info because “Well it works for me so must be okay”. A lot of my expertise is 20 years out of date and worked with super delicate security systems that required strong, stable power sources to detect intrusions. These days you could build the same thing for lest than 50p with tech from Asia.

But I love making things which is why I got into CNC in the first place. Anyhoo... I’m going to shut up until I can reduce my meds come spring.

[Kitwn]

Don't fret mate!
My radio/TV background doesn't allow for much ripple on a DC power supply so I was expecting to see huge quantities of expensive smoothing capacitors on a linear supply of the sizes discussed here. For this application you don't need that much.

I'm not brainy enough to use Faraday's Law to work out the inrush for a given transformer, but I suspect you need a pretty chunky lump of iron for that to be the only significant contributor to the overall inrush.

[NeoMorph]

Don't fret mate!
My radio/TV background doesn't allow for much ripple on a DC power supply so I was expecting to see huge quantities of expensive smoothing capacitors on a linear supply of the sizes discussed here. For this application you don't need that much.

I'm not brainy enough to use Faraday's Law to work out the inrush for a given transformer, but I suspect you need a pretty chunky lump of iron for that to be the only significant contributor to the overall inrush.

Hah... try doing math when your head is on the equivalent of 10 pints of lager. I read some of the posts here and go, “Errr... what the heck? The drives can take AC direct from the transformer... that ripple is going to be awful!”, without thinking it through that the drive itself will do the cleaning.

This is the problem with someone who knows a little bit of knowledge and thinking they know what to do (that’s me btw). Unfortunately, microelectronics which is VERY pick about power stability and a CNC drive that is going to take 60v from an AC transformer is two very different things.

Unfortunately I won’t be able to get my kit for at least a month apparently... nobody appears to be working at the factory/distributors in China. They are talking 2 weeks to even start back up again and maybe longer.

[Juranovich]

Do not rely on the OV protection of these drives, they will not save you from more than just a few volts. So if you get a spike then they will fry them.
They are good drives provided you leave a good safety margin.

You need to leave at least a 10% safety margin on the voltage and I wouldn't run much above 60Vac with 70Vac Max.

Regards the Transformer I use 750Va with these drives without any issues. I wouldn't go above 750Va because you will get troubles from inrush.

Do NOT use a regulated PSU like as been suggested by one member as it could cause you troubles with voltage clamping.

Now this gets fun! So, given that I want steppers around 4Nm. They usually (based on my google searches) come rated at 4-5A and 2-3mH inductance meaning total drawn amps are in the range of (Atot_= 2/3*pcs*Arated) 10.5-13.5Atot and Vmax (=32*√mH) 45-56V.. Now based on what I've picked up in this discussion I want to give my drives as much voltage as possible (minding 10% safety margin) and restrict the PSU to 750VA due to inrush. Say I supply 60V to 70Vmax drives, that means the 750VA PSU supplies 12.5A of current i.e. steppers should be rated at 4.5A (~12Atot) or lower in order to get max performance out of them (naturally I could have higher rated steppers, but that would be wasted monies, correct?). Am I correct in this logic?

Moreover, is the performance of the steppers linearly related to the current supplied or is there some leverage at play, i.e. say I supply a stepper with 4.5A, now will a 5A (arbitrarily chosen) rated stepper perform equally well as a 4.5A rated stepper would?

[JAZZCNC]

Say I supply 60V to 70Vmax drives, that means the 750VA PSU supplies 12.5A of current i.e. steppers should be rated at 4.5A (~12Atot) or lower in order to get max performance out of them (naturally I could have higher rated steppers, but that would be wasted monies, correct?). Am I correct in this logic?

Well, it depends on how many drives you intend to use now and in the future. Maybe you might add a 4th axis.? In this case, the 750Va allows a little overhead. However, what I didn't mention so as not to confuse the issue is that I've also used 625Va without any issues. But I knew this machine wouldn't need 4th axis because it was fitted with a 4th Axis that was powered from a separate smaller PSU.


Moreover, is the performance of the steppers linearly related to the current supplied or is there some leverage at play, i.e. say I supply a stepper with 4.5A, now will a 5A (arbitrarily chosen) rated stepper perform equally well as a 4.5A rated stepper would?

If using the Same Voltage then the 5A motor will have lower overall performance than the 4.5A motor. It will have a little more torque lower down the range but the RPM will be lower. This is mostly due to inductance because the higher current motor will have more inductance. It will also create more heat which robs performance.
In this case, half an Amp is neither here or there so wouldn't be a big difference and you'd hardly notice it. Thou any gains would be offset unless something else changed ie: Voltage. Everything comes at a cost.!

In a nutshell, Higher Amp's which often = higher inductance means higher voltage to reach the same speed. This is why often a 4Nm Nema23 will outperform a 4Nm Nema34 motor if using the same volts.
It's also why Large Nm Nema 34, 42 size motors require Very high or better still mains level voltages to allow any reasonable RPM's. All the machines I build that use above 8Nm motors use Mains voltage drives.

People often mistakenly think increasing the current will give more torque, which it does up to a point, but it also increases heat which affects the motor's saturation point which then creates resonance etc so stalls at lower RPM.

It's a complicated formula with several twists depending on motor spec, wiring, etc also with the advent of Digital drives allowing much better performance then Old Vmax (=32*√mH) Formula is even less relevant because the motors can be pushed harder and heat is controlled better along with resonance.

All I can tell you is that if you run the motors at the Rated current with a Voltage 10% lower than the drives Max V you'll be getting the best performance. If you need a little more Torque then increasing the current will provide a little extra but will cost in terms of heat and RPM.

[Juranovich]

All I can tell you is that if you run the motors at the Rated current with a Voltage 10% lower than the drives Max V you'll be getting the best performance. If you need a little more Torque then increasing the current will provide a little extra but will cost in terms of heat and RPM.

After much googling and talking to my uncle who's an electrical engineer I think I've got my head around the basics of this. One thing i still find confusing however is that logically you'd want to run the motors at they're rated current but I keep reading that the drives only draw 2/3 of that assuming parallel wiring (hence psu should be sized 2/3*Atot). Now, are the drives able to supply the motors the full rated current even if only 2/3 of that is supplied by the psu (through some magic I don't understand)? Or is this 2/3-rule applied simply due to the fact that the motors are seldom simultaneously drawing all of their rated current?

[AndyUK]

Or is this 2/3-rule applied simply due to the fact that the motors are seldom simultaneously drawing all of their rated current?

I think its that you'd never power all phases of the same motor to 100% of their current at the same time? But I'm sure one of the electronics experts around here will come up with a much more detailed answer! The 2/3rds rule is for parallel wiring, and for series wiring you can get away with 1/3rd.

I'd wager the answer is in here: http://homepage.divms.uiowa.edu/~jones/step/index.html (I just don't have the time to read it all!)

[JAZZCNC]

After much googling and talking to my uncle who's an electrical engineer I think I've got my head around the basics of this. One thing i still find confusing however is that logically you'd want to run the motors at they're rated current but I keep reading that the drives only draw 2/3 of that assuming parallel wiring (hence psu should be sized 2/3*Atot).

Be careful here when talking with electrical engineers ie: Domestic electricians or maintenance electricians because while they know how electricity and how circuits work etc I find they don't always understand or realize how different a Stepper driven machine differs to say typical AC motor system.
A stepper drive uses a chopping system to control the current/voltage that steppers require so it's not straight forward in terms of power draw etc like it is with say an AC motor connected straight to mains voltage.
The drives use a chopping system which uses PWM which only draws current 50% of the cycle on time. This power is taken from the capacitors in the DC system (AC drives just rectify inside the drives to DC) so during the Off cycle time the capacitors are recharging so only drawing power 50% of the time.
This is one of the reasons why the PSU can be sized lower than total Motor ratings. The other reasons being Not all Motors will draw full current all of the time and if they do then it's for very short periods and the Capacitors and drives will deal with any shortfall.


Now, are the drives able to supply the motors the full rated current even if only 2/3 of that is supplied by the psu (through some magic I don't understand)? Or is this 2/3-rule applied simply due to the fact that the motors are seldom simultaneously drawing all of their rated current?

Above should explain this hope fully.! . . . . Don't try to overthink this, I understand the need to understand how it works but if you want to build a good machine then what's been suggested will work great. You could spend weeks or months learning how it all works and you'll still end up back at what's been suggested.
Go with what's proven to work and you won't go wrong.

[Kitwn]

The rated current of a stepper motor is the maximum permitted continuous current in each winding. This will flow in the windings when supplied at the rated fixed voltage, something you will never do in practice for the reasons Dean has outlined above.

[Juranovich]

Above should explain this hope fully.! . . . . Don't try to overthink this, I understand the need to understand how it works but if you want to build a good machine then what's been suggested will work great. You could spend weeks or months learning how it all works and you'll still end up back at what's been suggested.
Go with what's proven to work and you won't go wrong.

This! Even though I'll probably end up building my machine according to the various suggestions I've got, I still cannot bring myself to do something without having built an understanding of my own of the matter. Hence, the occasional silly questions :)

[Juranovich]

Moving on to the mechanical side of things (at least for now) and essentially the gantry arm design. Am I right in assuming that it is the centre of gravity of the entire gantry assembly (incl. gantry arms, beam, z-axis, spindle etc.) that preferably should be half way between the X-axis (long axis) rail carriages?

My thinking is that any force applied to the spindle in the X direction affects the balance of the entire gantry assembly. Now, the reason I'm double checking this is that when drawing the gantry assembly (as in the attached, albeit, unfinished drawing) I find that the COG is quite far back (the left side mark) if the beam is also included in the calculations. I know some parts are still missing from the drawing, but even when included, the end result will not change much (in fact, what's missing is mostly parts on the left hand side of the mark). Bottom line is, in this scenario my gantry arms would raise straight up from the X-axis carriages (hence, neither would the inclusion of the arms affect the cog) and, essentially, leaving the spindle quite far in front of the front carriage.

Problem is that nearly all gantry arm designs I've looked at will have the spindle closer to the halfway point between the carriages or at least somewhere between the carriages. Now, when I calculate for the Z-axis assembly only (the mark to the right) the COG is naturally much closer to the spindle, and should I use this as my reference point my gantry arm design and more importantly the spindle position (relative to the X carriages) would end up looking much more like what I see others using. My intuition still says I should go with the COG of the entire gantry assembly as my reference point, but seeing that this would end up looking much different to the norm, it makes me wonder if I've overlooked something or simply using the wrong logic?

27318

[JAZZCNC]

I still cannot bring myself to do something without having built an understanding of my own of the matter. Hence, the occasional silly questions :)

The only silly question is the one you don't ask...Keep firing away we understand.!
What's I'm trying to say more than anything is don't let it slow you down from building because you'll still end up back at or around what's been suggested.

[Boyan Silyavski]

Best would be if Spindle centre /the bit/ does not go further than than carriage, machine looked from side . But If not possible its not a problem . If square linear rail is used. Though for metal work i say better not, for a perfect finish i mean.

Red line shows the ideal, blue line the normal. I would say 250-260mm span for me is the minimum of the gantry legs/ bearings


27319

[JAZZCNC]

Moving on to the mechanical side of things (at least for now) and essentially the gantry arm design. Am I right in assuming that it is the centre of gravity of the entire gantry assembly (incl. gantry arms, beam, z-axis, spindle etc.) that preferably should be half way between the X-axis (long axis) rail carriages?

Yes Ideally but again without wanting to sound like a broken record don't let these kinds of details bog you down from the building phase. The COG being off a little like what your showing isn't going to make one jot of difference to how the machine performs or how it affects component life in a DIY environment.

Anyone who's built a machine and worried about these kinds of things will tell you that it was a pointless exercise and it's the smaller details that make a bigger difference to how the machine performs. Details like sturdy ball-nut brackets and adjustability, motor mounts, wire routing, Limit SW placement, access to grease nipples and lubing, etc, etc.
If you build a Sturdy structure and pay attention to key areas like Z-axis then you won't go wrong or notice if COG is off a little, but you will notice if the little details are missed.

My advice is to look around at other builds and pay more attention to the little details and pay less attention to if COG looks a little offset.!

[Juranovich]

Best would be if Spindle centre /the bit/ does not go further than than carriage, machine looked from side . But If not possible its not a problem . If square linear rail is used. Though for metal work i say better not, for a perfect finish i mean.

Red line shows the ideal, blue line the normal. I would say 250-260mm span for me is the minimum of the gantry legs/ bearings


27319

I've planned on using a 250mm span between the outer ends of the square linear rail carriages and as it stands right now the arms would look like the blue lines in your sketch (though if cog is centered with centre of carriages the bit would fall outside or just on the outer edge of the front carriage). For reference the alu extrusions are 45x90.

[Boyan Silyavski]

I've planned on using a 250mm span between the outer ends of the square linear rail carriages and as it stands right now the arms would look like the blue lines in your sketch (though if cog is centered with centre of carriages the bit would fall outside or just on the outer edge of the front carriage). For reference the alu extrusions are 45x90.

It does not matter as far as you use Hiwin 20 size or comparable rails. You could offset al gantry rail to the back, to compensate a bit for this. As Dean says look at other build for inspiration and to figure the details.

I will not tire to say that machine is as strong as its weakest point, so do not overbuild / did i just say that :cat:/ just take care not to have weak details

[JAZZCNC]

I've planned on using a 250mm span between the outer ends of the square linear rail carriages and as it stands right now the arms would look like the blue lines in your sketch (though if cog is centered with centre of carriages the bit would fall outside or just on the outer edge of the front carriage). For reference the alu extrusions are 45x90.

If it helps I use 300mm wide plates with this design.! Anywhere between 250 and 300 will work ok.
However, keep in mind how you are going to fasten the profile to the plates and fasten the plates to the bearings if going with gantry on rails setup.! It's easy to forget things like access to bolts or one blocking another.!

[JAZZCNC]

I will not tire to say that machine is as strong as its weakest point, so do not overbuild / did i just say that :cat:/ just take care not to have weak details

I DO NOT BELIEVE WHAT I'M READING...:toot::toot: . . . FINALLY......:toot::toot:...We agree on something...:joker:

[Juranovich]

Anyone who's built a machine and worried about these kinds of things will tell you that it was a pointless exercise and it's the smaller details that make a bigger difference to how the machine performs. Details like sturdy ball-nut brackets and adjustability, motor mounts, wire routing, Limit SW placement, access to grease nipples and lubing, etc, etc.
If you build a Sturdy structure and pay attention to key areas like Z-axis then you won't go wrong or notice if COG is off a little, but you will notice if the little details are missed.


That's the paradox I guess! I keep reading all the theory but as I haven't done this sort of a project before it's hard to tell what's essential and what's not. And as you rightly point out, doing the details/assembly properly will matter quite a bit for the end result (as it would for any project really), maybe even more than getting all the theory right ;)

[Juranovich]

It does not matter as far as you use Hiwin 20 size or comparable rails.

20mm is the plan, but not sure yet about going full hiwin or not...


If it helps I use 300mm wide plates with this design.! Anywhere between 250 and 300 will work ok.


The idea crossed my mind. Would help bring the cog slightly forward + more stability.

I could also get creative and hang a 5kg weight from the spindle :D that should balance it up!

[JAZZCNC]

That's the paradox I guess! I keep reading all the theory but as I haven't done this sort of a project before it's hard to tell what's essential and what's not. And as you rightly point out, doing the details/assembly properly will matter quite a bit for the end result (as it would for any project really), maybe even more than getting all the theory right ;)

Yes, Theory is great. However at the DIY level theory and reality often part company early on in the build process at which point reality often comes back and smacks you fully in the face.
I find if you have patience use Common sense along with doing the Duediligence like what you are doing now. Then provided you choose the right design for your needs and take care when building it that you will always end up with a machine to be proud of that won't disappoint.

Keep asking the questions like what you are doing and it will eventually make more sense, it won't make complete sense until you started the build, which at some point you will say "Aghh I get what Boyan was saying now." .!!

[JAZZCNC]

20mm is the plan, but not sure yet about going full hiwin or not...

If you want the best machine then you must bite the bullet and go with Profiled linear rails. If not then you are wasting your time worrying about things like COG or plate thickness because Boyan is 100% correct that the machine is only as good as the weakest link and round rails will by far be the weakest link no matter which axis you put them on.!

[Juranovich]

If you want the best machine then you must bite the bullet and go with Profiled linear rails. If not then you are wasting your time worrying about things like COG or plate thickness because Boyan is 100% correct that the machine is only as good as the weakest link and round rails will by far be the weakest link no matter which axis you put them on.!

Sorry for being a bit unclear, with "full hiwin" I meant as opposed to the "economy" type profiled rails. I've already been convinced to go profiled, although I expect to swear a few times more than had I gone with round rails...

[AndyUK]

I could also get creative and hang a 5kg weight from the spindle :D that should balance it up!

Someone hasn't yet gotten into the theory of their motor calcs yet! More mass on the Z axis means everything has more to accelerate! NIGHTMARE!!

Personally I think we should all just make them out of bamboo and some twine, powered by hamsters, and tamagotchis as control interfaces to just be done with it :)

[Juranovich]

Someone hasn't yet gotten into the theory of their motor calcs yet! More mass on the Z axis means everything has more to accelerate! NIGHTMARE!!

Personally I think we should all just make them out of bamboo and some twine, powered by hamsters, and tamagotchis as control interfaces to just be done with it :)

Interesting point! But you still have to considered the torque drop when hamsters get hungry and be sure to size the running wheel according to your choice of hamster, too small and your hamster will simply get stuck and start doing loops...Other than that you should be sweet :beer:

[JAZZCNC]

Interesting point! But you still have to considered the torque drop when hamsters get hungry and be sure to size the running wheel according to your choice of hamster, too small and your hamster will simply get stuck and start doing loops...Other than that you should be sweet :beer:

Arghh but you'll always struggle if you use hamsters, what you need with a heavy Z-axis is Guinea Pigs...:yahoo:

[Desertboy]

Welcome to the forum :)

Yeah... this is quite a time-sink (and potentially money-sink) of a hobby.... ;)

Based on your post title, I'm guessing you were thinking of grabbing one of those pre-made Chinese jobbies off ebay?

They get an awful lot of flack (from me too!) but I think they do actually have a place; as long as you're prepared for how pathetic their capabilities are, they're a reasonably inexpensive way of experiencing the CNC process and way of thinking, allowing you to start exploring what you might want out of a machine.

The Shapeokos of the world give the same lessons, but are more expensive to begin with, although probably allow a greater amount of time before you outgrow it.

My first CNC was a simple conversion of a 3D plotting tank (think 40x40x40 work area, but about as stiff as jelly). It taught me lots about GCode, CAD CAM and what I needed from a machine.

I built my CNC after building a Rep Rap it really helped get my head around how it all works.

Hiwin's and ballscrews but the core principles remain the same.

[Desertboy]

Sorry for being a bit unclear, with "full hiwin" I meant as opposed to the "economy" type profiled rails. I've already been convinced to go profiled, although I expect to swear a few times more than had I gone with round rails...

For a first time hobby builder I think clone rail is fine, BST automation on Alixpress are a good place to start.

If I was sinking thousands into a frame, decent spindle, etc I'd buy original and I already have original Hiwin on most my machine just one axis is clone.

I can tell you Hiwin's are definitely smoother than cheap clone rail before I fitted them but in practice on the router working you can't tell the difference. With 1610 ballscrews one step in 0.05mm so that's really what limits your resolution. Never consider microstepping actual resolution it's something very different. On a Mill clone rail probably makes a lot less sense.

If I was working it for cash 10 hours day I would definitely go original Hiwin.

[Desertboy]

If you want the best machine then you must bite the bullet and go with Profiled linear rails. If not then you are wasting your time worrying about things like COG or plate thickness because Boyan is 100% correct that the machine is only as good as the weakest link and round rails will by far be the weakest link no matter which axis you put them on.!

It was because of you and Boyan I never used the SBR 25 rail I have and bought Hiwin's and clone hiwin's.

One day I might use them for a plasma cutter, I did buy new bearings for them they do feel "nice" but very glad I went with rail instead.

One really annoying thing about them the mounts are 46mm apart.

[JAZZCNC]

For a first time hobby builder I think clone rail is fine, BST automation on Alixpress are a good place to start.

No that's wrong way to look at it. When buying from China most of the cost is the shipping, the difference between Hi-win and the clone isn't massive so it's not worth wasting shipping. Don't spoil a machine for just a few $$ more.