Beginner MYCNCDIY Mill Build questions

I am trying to build the following machine (https://wiki.hackmanhattan.com/image..._eBook_1-4.pdf) which has a cutting area of 8.5" x 7.5" x 3". For my applications I require to machine hard woods for long periods of time and if possible in some very rare cases 10mm thick mild steel ran at very slow speeds for which bad precision and long machining time is not a major concern.

The question now is, what size NEMA stepper motors do I need to do this and is the frame suitable for my application? I saw within the document that the frame can be made to suit NEMA 23's, what size would be recommended and what controllers are recommended for this?

Please note that as this is a small low budget build, if possible I would try to keep the parts (motors and drivers) cheap (long lead times for part delivery will be OK). I have access to workshops, the time and material to manufacture the frame therefore, this should not be much of a problem.

Forget mild steel, that machine is too flimsy and spindle too weak to do more than scratch the surface. It'll struggle with any serious hardwoods but will probably manage mdf and ply ok and might be good for PCB routing. Watch the YouTube videos, it's struggling with mdf and feed rates are like watching paint dry. What are you planning to make that fits in such a small work area?

NEMA 23 3Nm low inductance motors (4mH or lower) - not because this machine needs them, but because they'll be reusable on the next one which is properly designed to meet your needs.

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Originally Posted by suraj1793

For my applications I require to machine hard woods for long periods of time and if possible in some very rare cases 10mm thick mild steel ran at very slow speeds for which bad precision and long machining time is not a major concern.

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Sorry but your wasting your time and money.? Completely forget any ideas of cutting steel or even aluminium. In all honesty it will struggle to cut hardswoods very well.

What motors to use are least of your troubles in all honesty. The fact this machine uses's threaded rod is a much bigger issue because this will severly limit the performance so which motors or drives/psu doesn't matter as the screw pitch will be the choker regards speeds not motor size.!
Feeds and speeds required for cutting hard woods will be outside of what this machine can reach due to tiny pitch of the threaded rod. Then you have the accurecy issue or lack of it from threaded rod. Combine this with known problems like wearing out the lead nuts which means your constantly chasing the machine and poor repeatabilty then your on hinding to nothing and much frustration.

Personaly I would look around at other designs and try to find some better cheap linear components like supported linear rails and ballscrews.

Thanks for sharing your knowledge and experience guys, you saved me from potentially wasting a lot of time and money.

For this build I have access to a car repair workshop (which also dismantles cars/vans) and a college workshop, both of which I can get free materials (such as steel frames supports, box section, sheet metal, etc) and equipment (such as mig welders, fasteners, power tools and hand tools) from and time is also not a major concern. I will continue looking for more rigid frame designs for this however, as I knew that both finding a decent frame and building it would take me a long time, I thought that I would be better off buying in the motors and drivers early on at a cheap price with huge lead times so that by the time the frame was towards being complete I would have everything ready therefore, if you know of such suppliers (cheap costs with long lead times) I would greatly appreciate it if you could send me a link. Also, any recommendations on cheap drivers?

I will look around for the linear components and frame design's, if anyone has any information or links to this please could you let me know. Or even better, if anyone knows of what these components could be salvaged from (ie home appliances or common equipment), I could possibly find that.

Also, as mentioned I will have access to complete cars and vans for any parts that can be salvaged from them for this build therefore, if you can think of anything that may be useful from these please could you let me know.

EDIT; Sorry, forgot to answer your question, I am using this to manufacture small extrusion dies for the end of a rubber extruded (only a 60mm diameter die with a machined profile within it) The larger size bed was really for small wood work hobby jobs. Could smaller size motors be used for such work?

Cheap motors and drives will end up being expensive throwaways as they simply won't perform and you'll end up buying something decent in the end anyway.

Lets start with your extrusion die requirement. What material and what's the profile look like? I suspect you're approaching the problem from the wrong angle but lets not prejudge it.

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Originally Posted by suraj1793

I will continue looking for more rigid frame designs for this however, as I knew that both finding a decent frame and building it would take me a long time,

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look here; http://www.mycncuk.com/forums/253-DI...ter-Build-Logs

Start on the last pages of a thread and work forward, that way you can usually see the finished machine first to see if it interests you.

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Originally Posted by suraj1793

therefore, if you know of such suppliers (cheap costs with long lead times) I would greatly appreciate it if you could send me a link. Also, any recommendations on cheap drivers?

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http://www.aliexpress.com/wholesale?...SearchText=cnc
ebay (Chinese sellers)

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Originally Posted by suraj1793

Or even better, if anyone knows of what these components could be salvaged from (ie home appliances or common equipment), I could possibly find that.

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Highly unlikely or none.

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Originally Posted by suraj1793

Also, as mentioned I will have access to complete cars and vans for any parts that can be salvaged from them for this build therefore, if you can think of anything that may be useful from these please could you let me know.

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Highly unlikely or none.

Suraj let me just say that trying to build any CNC machine on the cheap never works.!! . . . . It always costs you more in the end.! . . .BUT . . . Trying to build one capable of cutting steel on the cheap is DOOMED from the beginning.

The best advice I can give you is STOP.!! . . . Don't do or buy anything as you simply haven't spent enough time doing the research that will be neccesary to achive building any CNC machine let alone one built on a budget for cutting hard materials. And I'm Not even meaning steel just the more dense Hardwoods or aluminium, Steel is a whole differant ball game which I suggest you forget for a first build.!

Go read most of the build logs to get some idea of just what's involved in building any machine. Read them properly not just flicking thru as you'll learn more that way.
Read every thing you can, then read some more and just when you think you have it sussed read it all again then come back with a design and we will start with the advise.
While doing this Save up your money and forget trying to build cheap it just never works out cheap in end.!

Thank you for all of the comments and suggestions, I have been reading up on build logs on both this forum and CNCZONE and only now am starting to understand the scale of the machine required to meet my manufacturing requirements and reading your comments/advice further confirmed this.

I will continue reading and researching CNC builds to gain a better understanding of what I need to do but would appreciate it if you could guide me on what is a "doable first build" so that I can base my research accordingly, I mean machining aluminium would be more than perfect for both my extrusion dies and so much more! but is this a practical goal for a first build?

I also learnt from your comments and other forum posts that with DIY CNC machines, cheap is BAD!!! But just to get a sort of indication of how much this build would cost me (machining aluminium) could you please let me know how much everything other than the frame (which I will be building myself) would be as an estimate (ie, steppers, drivers, power supplies, etc)?

this guys build thread here give a break down price of all the parts.

though its designed for woodworking and not ali.
but it gives you an idea.

Since my last post i have read LOTS of logs and researched this topic in much more detail and think I have finally found something I think will be suitable for what I require:

http://www.mycncuk.com/threads/1541-...-framed-router

ivars211 had started designing/researching this build also (http://www.mycncuk.com/threads/7412-...C-router-build) however, changed his design but did provide a lot of useful points and information.

I would try and use the mill for mainly wood work (40mm deep cut maximum) and some aluminium, my questions are:

- Is this machine setup suitable for my requirements?

- Ivars211 in his thread initially wanted to go for this kit (http://www.ebay.co.uk/itm/German-Shi...MakeTrack=true) however, was warned against it due to the high motor inductance (3.8mH). I am not sure if he used this kit however, in the thread it was recommended to use something at or less than 3.5mH. Would 0.3mH really make that big of a difference? This seems like a great price but not sure if I would be buying bad quality stuff if I went for it.

- For this build would it be suitable to use a roller carriage type setup for all linear carriages as shown here (http://www.cncrouterparts.com/linear...ent-p-100.html) with cold rolled steel as the guide rail? Would the machine still be fairly accurate?

Did some more searching and found this (http://www.mycncuk.com/threads/5790-...tor-and-drives), in this post JAZZCNC also highlighted the fact that 3.8mH is slightly high for motor inductance therefore, my first question has already been answered (unless the inductance rating depends on the application?).

Therefore, I started searching again for available kits/equipment for the electronics part of this build and heres what I found:
Stepper Motors: As per recommendations in Ivars211's thread (http://www.cnc4you.co.uk/index.php?r...product_id=362)

PSU: This was a bit confusing. In JAZCNC's post it was highlighted that for best performance you should run the motors at around 60-70VDC however, the kit on ebay shows 2pcs PSU 350W (36VDC/9.7A) and the 3 axis kits for running 3.1nm steppers on CNC4YOU.com showed 1pc 400W (36Volts) PSU. Are the kit PSU's just making use of large safety margins for the supply? If so, should I be looking for a PSU rated at 60-70V and 8-9A? Does anyone have any recommended suppliers? (Will be looking into building toroidal PSU if necessary)

Drivers: As per the ebay kit (http://www.ebay.co.uk/itm/3Axis-Step...item2eca734c31) However, I just noticed that these are rated at 50V and as per recommendations in the post they should be rated higher than the maximum applied voltage (which is recommended at 60-70V) therefore, are these the wrong drivers? If so, are there any suitable alternatives which are in the same price range? The AM882 were a bit out of my price range for this first build however, seem like a very good upgrade for the future.

All depends on the size of the machine and the weight of the gantry. Then come the motors and so.

What working area??? What is the hardest material you will machine? How much money are you ready to spend on the build?

After much guidance and a lot of build log reading I think an achievable goal for my first build is to be able to machine wood (typically at around 40mm depth) and be able to do a lot of carving work (although if I can get more depth it would be preferred). If this could also engrave aluminium this would be a major benefit (although not my primary purpose for this machine).

Cutting area for this would be around 500mm x 500mm. Material and equipment for the frame (steel or aluminium box section, mig welder, drill press and hand tools) are all available for free from work. For the rails I was going to use roller carriages with a cold rolled steel plate as a guide rail and for the linear motion of the axis I was going to be using ACME threaded rod (but setup for later replacement with ball screw).

For the spindle I was thinking of initially going with a simple router like a bosch colt or maybe something smaller which I have already in the workshop such as a pnematic dremel but after some time upgrading to something like a 2.2kW spindle dedicated to the machine.

Budget for the electronics (motors, drivers, PSU) is around £200.

This build seemed to suit all my requirements therefore, I planned on using this setup as a guide: http://www.mycncuk.com/threads/1541-...-framed-router

This was another build I was looking at as an alternative but I am not sure if it would be powerful enough for what I need: http://www.neo7cnc.com/

Also, it may be worth mentioning that I also have an arduino uno available so was thinking of running this from GRBL as this would allow me to use my laptop USB for to communicate with the machine.

I am not a fan of "ultra cheap" builds as at the end you will have "ultra nothing" as a result and money spend for nothing.

500mm wide working area suggests 2 motors at the long axis that moves the gantry hence 4 axis board. 100-300 euro, i would say 200 euro here only for the BOB. Now if you could avoid somehow this using arduino or whatever cheap. / Saying cheap i don't mean crap Chinese boards without support

Next thing are drivers and motors. if the gantry is No more than say 300mm wide, low voltage drivers and motors are possible/<55VDC/ , for 500mm gantry if you want to achieve normal speeds you will need drivers capable of 70-80VDC and motors 4.2A / 3Nm/ . 4 motors here are 100euro and 4 drives 180-250euro

So you see you have to invest if you want something capable.



But lets start backwards.

What you will 100% need is ball screws and square rails, given the current prices you will save next to nothing using round rails.

So start from the frame, the rails and the ball screws. Cause that you can not change later. When you have money just continue the build.

Take care at the steps below or you will spend unnecessary amount of money due to mistakes

1.Make the drawing
2.Show it here
3.Receive critique
4. Finalize the drawing
5. Buy ball screws and rails.
6. Make frame
7. Buy motors,
8. BOB. drives.....etc.

Hope that helps you to organize your thoughts

Thanks for explaining silyavski, I keep on underestimating the scale of these builds...I just see some real good builds and instantly want to try and make them! but I have to start understanding that quality costs money!!!

After re-evaluating my requirements and realizing that wanting a router that can machine both ali and wood is a "typical beginner question" I decided upon a simpler first build. The requirements are, a small 300x300 router that is dedicated to wood work (mainly carving and some involving 40mm deep wood cutting on softer woods). As it would be for carving work I am not trying to hold very tight tolerances, just enough for the carved features to look "right" which I am guessing gives a tolerance of around 0.2mm or maybe even more.

A perfect example of what I am talking about is something like this: http://www.youtube.com/watch?v=OX_Pw8XPYMs
Some of the basic specs are shown here (http://www.busybeetools.com/products...LIVER-CSA.html) this shows that the router uses 240 oz-in motors and just a 150W spindle all of which seems to be closer to my budget than other machines I have seen.

Do you think this is a bit more doable for me with my budget? Like I said, all I am looking for is a decent wood carving router that can be ran continuously.

Ok. I understand.

The example you gave is "perfect" example of crappy machine with good marketing. In fact i have something quite similar and i bought it because there was no body to help then and explain me that:
All cheap systems of linear movement are crap and only the square supported rail is the real thing. So as i said, whatever you do, don't go that way/ v wheels, round rails, etc./ Whatever they say!

So go to ebay or BST Automation and search for supported square rails, Hiwin, chinese or whatever. Just saw that Zapp automation has some great deal on ISEl http://www.zappautomation.co.uk/surplus-stock.html you will need size 20 rails and blocks.


Next you will need to know the ballscrew price more or less, BST Automation

So you decide if its doable or not, just follow the steps from my previous post. Dont start the build until you have the screws, rails and nut housings in your hands.

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Originally Posted by suraj1793

Do you think this is a bit more doable for me with my budget? Like I said, all I am looking for is a decent wood carving router that can be ran continuously.

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What is your total budget for a fully working machine.?

From what I've read here, I think you would be better off buying a Chinese 3040 off ebay.

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Originally Posted by EddyCurrent

From what I've read here, I think you would be better off buying a Chinese 3040 off ebay.

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Nah I wouldn't.!! . . . I'd encourage him to save up a little more and not waste is money on Rubbish.!!

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Originally Posted by JAZZCNC

Nah I wouldn't.!! . . . I'd encourage him to save up a little more and not waste is money on Rubbish.!!

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But that's exactly what he's proposing to do anyway, at least the ebay job is ready built and more importantly saleable again.

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Originally Posted by EddyCurrent

But that's exactly what he's proposing to do anyway, at least the ebay job is ready built and more importantly saleable again.

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Not if he's smart and listens to experience talking and while Yes it will be saleable he'll still be losing money.!! . . . . If he saves a little more money he'll get exactly what he want's and when comes time to move on or needs larger machine he'll make money not lose.!

To me that's problem these days every body want's everything instantly but for nothing.!!. . . .Good things come to those that wait.!

Hi guys, my budget is around £400-£500. I was initially hoping to build something like this: http://www.mycncuk.com/threads/1541-...-framed-router and work on using it for carving and stuff like this http://www.youtube.com/watch?v=VhKl0...IyoicGWeJ5Z1gQ making use of roller carriages instead of supported round rails as shown here http://www.youtube.com/watch?v=5dmPV7TyzPg as precision is not a high priority for my build but not sure if this is possible with my budget. If not, I would be more than happy with a small router for carving work as shown in my previous post.

As mentioned, I can get box section (both steel and aluminium) and things like fasteners, welding equipment, sheet metal all for free from work. Also, I have an Arduino Uno which could run GRBL and connect directly to the drivers, so might be an option for a controller.

Well if you get all the steel and fastenings etc for free then you may and it's a very slim chance just about do it. . . .BUT . . . It will be compromised in performance and abilty.!
It will require great attention to detail when building to get even moderate accurecy. The inefficiency or the linear rails etc will require more power from motors to overcome any sticktion. Attention to little details of design like adjustments etc will be needed and you WILL constantly be chasing adjustments.

One problem with the bearing setup shown, and I have built like this so speaking from experience here, is that chips and rubbish become a problem with binding bearings. The bearings wear quickly so need replacing often, on upside they are cheap, but still a pain in arse.

To be honest to build anything like a decent machine that's worthy of the effort involved, which to be in no doubt is considerable, then £1000 is the minium needed to make it worth the trouble. If done correctly then your £1000 will earn it's self back in no time and really will be instantly in profit from day 1 as you could sell it for far more than it cost to build.!!

My advise as always in this position is save up and spend that bit more. Even of you buy a chinese router for £500-600 like Eddy suggest's then you'll end up spending £1000 by the time you have replaced the spindle and electronics when they die.!. . . . And they will sooner rather than later.!!

Thank you JAZZ!!! Given me the slightest of hope that this may be possible after all, although...after reading the rest of your post i'm not sure if that was your intention :joyous:

Just to confirm, when you say I have a very slim chance of pulling this off do you mean for building my dream steel router that pavlo had built in his build log or a smaller desktop router?

From what I understand the main cost for my first build will be the electronics (drivers, motors, PSU, spindle) as the materials and parts for the frame I can get for free or build myself (including roller carriages and ACME threaded rod). As you explained this will compromise the router quality and performance ability however, do you think this will still be "usable" for some wood carving work as long as I pay a huge amount of attention to detail?

The positive I see in trying this out (if there is any :cocksure:) is that if worst comes to worst, I have myself a decent set of motors, drivers, PSU and spindle and a router which cost me nothing but time to build.

Will start working on Solidworks models but do you think I should also start looking into the electronics now? In the build log he has used 3.1nm steppers, do you think these will still be OK with additional frictional load of the roller carriages as you had explained?

Thanks

Not with ACME threaded rod, the friction is too high and the pitch too low to get any serious performance. You'll be measuring job time in days rather than hours for anything remotely complex.

Thanks for informing me of this. Are there any other decent alternatives to this? I am going to look further into the rack and pinion type setup but if all fails I guess I will just have to go for ball screws.

EDIT: I understand that this is real sloppy for a CNC machine and I will probably look like I have gone mad for asking this but I just have to ask, could a rack and pinion obtained from a small car steering rack work as an alternative?

Suraj, Forget R&P from a Car but what you could use and is the next best thing to ballscrews for efficiency are timing belts and pulleys. BUT again I can tell you from experience that by the time you have bought all the pulleys and idle gears etc then they don't work out much cheaper than ballscrews from china.

Completely Forget threaded Rod it's absolute waste of time.

If you try to do this on the cheap I promise you will regret it and the only useful thing to come from it will be the painful lesson that it can't be done cheaply.!! . . . . . Don't get me wrong I'm not trying to put you off building a CNC machine, Far from it, I'm trying to steer you away from taking the expensive cheap route.!! . . . . Seldome does it work out Ok and nearly all those that do succeed end up building another as the first has too many weak areas to be worth while upgrading.!

Thanks JAZZ, I appreciate you warning me of the expensive lesson that I may learn and think it would be silly of me to ignore such advice. So, I think it would be best for me to hold off on the mill until a later stage. However, if possible, I would like to continue learning about CNC and at least work on some form of a CNC project which may be more doable with my current budget.

Maybe a conversion rather than a build? I have had an old round bed drummond type lathe sitting in the garage for a while, very similar to this one (http://www.lancerregister.com/showthread.php?t=378816) but a bit bigger. Do you think that this would be a suitable CNC conversion project which would be doable with my budget? If so, hopefully it could be set up such that I could use the parts I buy for future builds (motors, drivers, PSU, etc).

an interesting read this thread has been, and sort of reminds me on when i joined this forum
and wanting to build a dual cnc machine on the cheap.
and after getting much advice from the usual members, i decided to take the advice and not waste money on the expensive cheap route.!! ( as dean puts it :) )
and after seeing a picture of the mill i have converted to cnc.
i thought what a good idea.. so im saving up for good electronics.
that will serve me well and can be moved to another build later down the line if required.

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Originally Posted by T0rnado69

i decided to take the advice and not waste money on the expensive cheap route.!! ( as dean puts it :) )

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Yes strange statement but really is true. The difference between good and Bad electronics unfortunatly does kind of translate into Cheap or Expensive.
Again unfortunatly the Cheap route all to often becomes the expensive route and most anyone who as experienced the performance difference Good quality Digital drives make to steppers will tell you they are worth every penny. Equally anyone who as experienced the hair pulling head banging frustration of cheap nasty electronics will backup that it was an expensive lesson learnt.!

Put decent quality electronics with a good motion control card and you'll have hassle free machine that performs with the best of them.!. . . And will do it 24/7 for years.

So do you guys think that a lathe conversion is the way to got for me with my current budget? Is the round bed/old lathe setup I added a link to in my previous post (similar to the one I currently have) suitable for such a conversion?

In a word, no. That's not to say it can't be done as a purely intellectual exercise, just that the results will be disappointing, plus the cost of conversion will far exceed what the lathe is worth. And it won't be a quick exercise either.

As the owner of several pre-1930 British lathes I can tell you that the backlash in the lead-screws and the lack of rigidity in the bed/headstock/bearings/etc make it pointless. Manually operated, I know the machine's limits so know how far I can push it and leave some slack for the final finishing passes. They were very much a seat-of-the-pants exercise, feeling the tool/bed/headstock/bearing/workpiece deflections to creep up on the desired end diameter. A CNC machine simply cannot come close, it needs the rigidity and precision in the basic machine to start with.

Thanks irving, do you know of any other CNC projects I could work on which are within my budget? Been looking at plasma cutters which look interesting but I am guessing they are also expensive. If not, I guess I will have to just hold off until I can put atleast £1000 forward as per JAZZ's advice.

I know you're itching to start but patience is the name of the game here. I don't know your circumstances, but have you looked at ways to gain access to someone else's machine for example? Maybe there's a local tech college evening course, or a local small engineering firm that might be amenable in return for free labour - use your imagination and get creative!

Ok I can't see such enthusiasm go un-rewarded or dampened. . .:hysterical:

I'm very soon going to be upgrading my own machine with new profiled rails, ballscrews and nearly most of the gantry and Z axis in preparation for sale. So when I do then old ones are yours for just 24 pack of Guiness.!

They are very very well used with some wear but they will make a perfectly good machine with some TLC.
Linear bearings are Profiled Hi-win and still fine but ballnut/screws and end bearings are worn but with some new balls/bearings then they could be brought back to life and tweak a few more years from them.

There should be most of the parts needed for machine except the main frame. I'll PM you when they are off and available.

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Originally Posted by JAZZCNC

Ok I can't see such enthusiasm go un-rewarded or dampened. . .:hysterical:

I'm very soon going to be upgrading my own machine with new profiled rails, ballscrews and nearly most of the gantry and Z axis in preparation for sale. So when I do then old ones are yours for just 24 pack of Guiness.!

They are very very well used with some wear but they will make a perfectly good machine with some TLC.
Linear bearings are Profiled Hi-win and still fine but ballnut/screws and end bearings are worn but with some new balls/bearings then they could be brought back to life and tweak a few more years from them.

There should be most of the parts needed for machine except the main frame. I'll PM you when they are off and available.

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I already greatly appreciated your guidance and learning from your huge amount of knowledge and experience (that alone has saved me so much potentially wasted time and money for which I cant thank you enough) but, getting such a huge amount of help from you with parts for the build...I don't really know what to say but THANK YOU!!! I don't know how I could ever return such a big favor and know for sure that a 24 pack of Guiness is no where near enough to do so!!!

Thank you for everything, I am very grateful and owe you big time!!!

EDIT: Do you think that the following (http://www.mycncuk.com/threads/1541-...-framed-router) would still be a suitable build with these parts or is there something better suited?