Starting to design out my build, looking for critique

[Chrono]

Hello everybody!

I have been reading posts here and designing my own CNC for a while now. I have been sitting on this and not continued for quite some time, but I now have the opportunity to access a lathe and a well-equipped workshop for a couple of months, so I want to finally move this forward.

Before I go into the design, I want to quickly state what I want to achieve with this machine: I want a relatively large (read: Around 1m x 0.7m x 0.1m) area machine to cut wood, plastics and aluminium. At the same time I really want to constrain the cost as much as possible, not wanting to go over a cost of 4000€ (at this point I should probably mention that I am located in Germany).

Now with the information I have gathered, this is the design i came up with to satisfy these requirements:

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The Profile is Motedis 45x90S B-Type Slot Aluminium Profile, The rails are HIWIN rails and I am planning on using ballscrews for the motion. For the Rails and Screws I plan on buying a bundle on Aliexpress which will likely dictate the exact dimensions of the machine.

Now to the questions I am still having:

How would you go about connecting together the Profiles? Would angles suffice, or do you use something else there?
What would be the best way to mount the Rail Bearings? The green elements in my Model are just placeholders, since I struggle to find a good way to mount them.
How would I place Drag Chains on this design, to protect the cables? Would I need to make sure to have extra flat space to route these?
I was planning on using NEMA 34s with Timing belts to drive the screws. Would I need two of them for the Y Axis?
The Spindle Plate hanging on the Gantry looks huge to me, compared to the rest of the machine. Did I misdesign this?
Is a machine like this even capable of milling Aluminium? Would it be able to cut thin (not more than 10mm) steel sheets?
And finally, is this design even any good? I mostly worked off the information I found in various posts on this forum, especially for the gantry design, but I have no idea if the result has any glancing flaw.


Thank you for any help!

[AndyUK]

Is a machine like this even capable of milling Aluminium? Would it be able to cut thin (not more than 10mm) steel sheets?


Others will be able to say, but should be able to take light cuts in Ali. Steel is probably out of the question - for that you're better off converting an existing mill.



The Spindle Plate hanging on the Gantry looks huge to me, compared to the rest of the machine. Did I misdesign this?


Can't see it in the renders? The carriage plates look reasonable - but obviously there isn't a Z axis yet which will change things.



I was planning on using NEMA 34s with Timing belts to drive the screws. Would I need two of them for the Y Axis?


This size of machine should be fine with Nema 23, but that's just a mounting size. On your long axis, you can either go with a pair, or you can use a single motor with a timing belt connecting the screws. If a belt across the CNC isn't a massive inconvenience to you, my vote is for the belt - otherwise dual drive. There is a motor calculations spreadsheet on the forum which will help direct you to which motors to use.



How would you go about connecting together the Profiles? Would angles suffice, or do you use something else there?


You can tap the ends of the profiles and stick large bolts in, you can use angles, or you can use T-nuts. There are probably other ways - look at a Profile supplier's website for inspiration (e.g. KJN).




And finally, is this design even any good? I mostly worked off the information I found in various posts on this forum, especially for the gantry design, but I have no idea if the result has any glancing flaw.


Looks like you're on the right lines to me - I'd carry on by improving the detail of the CAD.

[Washout]

What would be the best way to mount the Rail Bearings? The green elements in my Model are just placeholders, since I struggle to find a good way to mount them.




Hi Chrono

Andy beat me to many bits of good advice, but I'll add:

Whilst some of the details are missing the green plate method, provided the plates are thick enough should be a good approach, as you will be able to adjust the plates to get the ballscrews aligned properly. In fact being able to make adjustments for alignment of ballscrews and stepper/servo motor mounting should be your aim when designing the mounting points/plates (with rigidity of course :-) ).

Your Z Axis carriage/box will likely need some side bracing of some kind to stiffen it - could be as easy as some triangular corner plates to tie the right angled joint together.

Hope that helps.


Chris

[AndyUK]

Andy beat me to many bits of good advice


There is a reason I picked which questions to answer and which to avoid!

Washout makes a good point about the adjustment of things. I like your ballscrew placement idea on the gantry, but it doesn't leave a lot of room for height errors - the location of the top plate will be defined by the carriages, which may or may not co-inside with the height of your ballnut support. You may want to design with say, a 5mm shim under the BK/BF12, so that you can adjust the shims to get the right height. This is why the ballscrew on mine is on the back of the L shape, it allows me to adjust for height relative to the carriages - but leads to a slightly more flimsy 3-sides of a box shape.

[Chrono]

Thank you two for the replies! I have been implementing some of the things you were talking about in my spare time, but much more needs to be done yet.

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What I changed:


I added angles and connector plates. My plan is to mount the spoilboard on the angles.
I added the Z-Axis. Currently, due to the different heights of the Rails and the Screw-sleds, the plate holding the spindle has a weird U-Shape. I could cut into the Z-Carriage and sink the screw into the gantry a bit to make this flat, but thus sacrifice gantry rigidity. Any thoughts on this?
I also added Angles to help support the Z-Carriage, like Washout recommended.


What I am yet to do:


I understand the thought about keeping the mounting plates adjustable, thus I will design out those green plates to make actual mounts. The same for the back bearings.
I want to add motors to both the Gantry for the Y-Axis and the Z-Axis. For the Y Axis I thought about mounting them in the sidepanel holding up the gantry. For the Z-Axis I thought about lengthening the top plate and hanging the motor there. Would this be a problem in terms of placing extra torque on the Gantry?


I also have a couple more questions:


Should I put in two more profiles to brace the bed in the Y direction? Crossbracing will be hard using only Aluminium profile
How thick should the different Alu plate parts, like the bearing plates, sidepanels and Z-Carriage be? Currently, I have all those set at 20mm thickness.
What about endstops? I have access to a 3D printer, can I use that to print mounts for the endstop sensors, or would those be too flimsy? I do not see them having to take much force, but maybe I am missing something here.



On your long axis, you can either go with a pair, or you can use a single motor with a timing belt connecting the screws. If a belt across the CNC isn't a massive inconvenience to you, my vote is for the belt - otherwise dual drive. There is a motor calculations spreadsheet on the forum which will help direct you to which motors to use.

What would be the advantage using a single motor? I am guessing the, more or less, guaranteed synchronization of the ballscrews?


I like your ballscrew placement idea on the gantry, but it doesn't leave a lot of room for height errors - the location of the top plate will be defined by the carriages, which may or may not co-inside with the height of your ballnut support. You may want to design with say, a 5mm shim under the BK/BF12, so that you can adjust the shims to get the right height. This is why the ballscrew on mine is on the back of the L shape, it allows me to adjust for height relative to the carriages - but leads to a slightly more flimsy 3-sides of a box shape.

Regarding this, would it also work if I were to flip-down the part of the Z-Carriage in the back that currently is mounted to the Screw Sled? That way I could freely adjust the height. I would only probably have to do it behind the current place where the screw is mounted, since I would hardly be able to actually screw anything in the other way around. Also, regarding the washers, would I just simply place washers between the sled and what I want to mount? The question arises, since that would massively decrease the area of contact between the two.

Again, thank you for the Replies!
-Chrono

[AndyUK]

I want to add motors to both the Gantry for the Y-Axis and the Z-Axis. For the Y Axis I thought about mounting them in the sidepanel holding up the gantry. For the Z-Axis I thought about lengthening the top plate and hanging the motor there. Would this be a problem in terms of placing extra torque on the Gantry?


As in, hanging the motor off the back of the carriage, the opposite side to the spindle? Don't think it'll be a problem in terms of torque on the gantry (else you're not going to be cutting much!), infact it may even help to bring your centre of gravity closer to the middle of the X axis bearings, which is where it should ideally be. The only issue I see is space, you won't be able to place the CNC up against something without loosing travel on X.


I added the Z-Axis. Currently, due to the different heights of the Rails and the Screw-sleds, the plate holding the spindle has a weird U-Shape. I could cut into the Z-Carriage and sink the screw into the gantry a bit to make this flat, but thus sacrifice gantry rigidity. Any thoughts on this?

I'd certainly be putting a second pair of bearings on that Z axis and lengthening the rail to retain your travel. Remember that the moment on that axis is Force x Distance to pivot - currently the pivot is the centre of your single bearing, the forces are at either end of the same bearing. With two bearings, the pivot becomes the point between them, and the forces are acting on the bottom of the bottom one, and the top of the top one. Your deflection in that direction will be significantly reduced.


How thick should the different Alu plate parts, like the bearing plates, sidepanels and Z-Carriage be? Currently, I have all those set at 20mm thickness.

What about endstops? I have access to a 3D printer, can I use that to print mounts for the endstop sensors, or would those be too flimsy? I do not see them having to take much force, but maybe I am missing something here.

20mm Ali plates for the main structures sound reasonable. Theres a spreadsheet on the forum for calculating gantry deflections that you should be looking at, and it'll give you an idea of how to approximate the cutting forces involved, and what deflection you'll expect from different materials. Regards endstops, I wouldn't be worrying too much about them just yet, but a 3D printed mount for the limit switches sounds like a good idea. With any luck they'll cut the motion before they take too much force, but having them break rather than damaging the linear motion components or your gantry sounds good ;)


What would be the advantage using a single motor? I am guessing the, more or less, guaranteed synchronization of the ballscrews?

Spot on - once you've set the relationship between the two screws with the timing belt, you don't need to worry about the gantry racking, or homing the motors independently every time you use the CNC to ensure a perpendicular X and Y. If you miss steps, they're missed on both sides - which is probably safer. Then theres the reduced complexity in limit and homing switches, and you don't have to buy yourself an extra servo/stepper driver which is £50-100 right there. You can also use a 4 axis controller and still have a spare axis for development later on.

... basically, I'm mildly regretting going for dual motors. But I didn't want the timing belt across the entire machine, so I'm paying the price!




Regarding this, would it also work if I were to flip-down the part of the Z-Carriage in the back that currently is mounted to the Screw Sled? That way I could freely adjust the height. I would only probably have to do it behind the current place where the screw is mounted, since I would hardly be able to actually screw anything in the other way around. Also, regarding the washers, would I just simply place washers between the sled and what I want to mount? The question arises, since that would massively decrease the area of contact between the two.


That sounds like how I've designed mine (see the build log).

Washers? I'd use some shim material which maintained the surface area.

[Chrono]

Sorry for the long radio silence, things have been quite busy here and I could barely find the time to work on this.

I took the advice with the Y-Axis Ballscrew and the Z-Axis sleds to heart and changed the corresponding geometry:
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On the to-do-list are the following things:
Add a mounting point for the Z-Axis NEMA 34 behind where the Y-Axis ballscrew currently connects to the Y-Axis sled.
Add an "Omega-Drive" belt structure to the front to run the two X-Axis Ballscrews from one NEMA 34 stepper. The "Omega-Drive" structure is there to maximize surface contact between Belt and Gears
Finally add that back ballscrew-bearing plate to connect it to the base structure
Add a Spot for the Y-Axis Motor to sit. Due to clearence with the Y-Axis sled I am still unsure where to put that, but maybe even below the X-Axis rails on the bottom?

Do any of these plans throw up a red flag from something I have not considered yet?

I have also been talking to the mechanical engineers in my workplace, who came up with a plethora of ideas to alter the design, so I am seeking a second opinion on some of these:
Substitute the Aluminium Profile for Steel Box section and weld it. The warping should be controllable in a machine this size, is what I am hearing.
Change the Y-Axis gantry to a design that has a Profile up top and one below with the ballscrew sandwiched in between. The rails would go to the front and both profiles would be held together at the sides, like they are now, and with an extra plate at the back. Alternatively manufacture this out of steel section.
And now to the weirdest one to me: Mount the gantry to the X-Axis like it is now, but only on one side. Then have the other side be out of thin steel with only a loose connection to the gantry beam, thus only inhibiting rotation, but not translation. This would "solve" the problem of the gantry being over-constrained, since the second beam would only brace against torque, but allow the gantry to move over it, in case the rails are not exactly parallel. I know that in theory this makes sense, but it still seems counter-intuitive to me in terms of rigidity.


In the mean time I will work on getting the steps on my to-do list done and report back once I am done with that!

[AndyUK]

Cool, changes look to be in the right direction. Z axis will be much more stable - even more so if you can space those bearings apart a bit.


Add a mounting point for the Z-Axis NEMA 34 behind where the Y-Axis ballscrew currently connects to the Y-Axis sled.

Woowwww there cowboy! Hold up a second! A Nema 34 for the Z axis? That's a little overkill. Get a much lower inductance Nema 23, gain yourself some performance by not having a big inertia to overcome (and take the extra mass from the moving carriage), and give yourself more space up on the Z. Something like 2-3Nm - even that will be more than sufficient.



Substitute the Aluminium Profile for Steel Box section and weld it. The warping should be controllable in a machine this size, is what I am hearing.


Certainly do-able. I planned to do the same myself initially. But the welding will warp it, and mild steel box section is nowhere near flat to begin with, so either way you'll need to mill the faces you want to mount rails to. Or, you can epoxy them, but that won't be easy to get the two faces parallel. Then you have to consider how to attach the box section to the gantry end plates, which probably means capping them off and tapping them etc.

Rigidity? Look at my build thread. I simulated a steel L shape out of a box and a rectangle, then I simulated a slightly smaller Ali HD profile. Although the young's modulus of Ali vs Steel says you'll get more deflection from Ali, when you take the profile shape into account its really minimal. I think I went from 3um deflection in steel to 4um in Ali (but the real numbers are in the build log). Either way, its nothing to be concerned with.

Profile Ali is flat enough to mount straight to and just shim where and if needed. It also has nice ends which can be tapped in about 5mins and bolt directly onto your end plates.

Weight? Every extra kilo is lost acceleration!

Next question is cost - In my case, the aluminium was only marginally more expensive. Really not much in it - Approx £40 for steel, and £50 for Ali. The ease of Ali just won the day for me by a long margin.



Change the Y-Axis gantry to a design that has a Profile up top and one below with the ballscrew sandwiched in between. The rails would go to the front and both profiles would be held together at the sides, like they are now, and with an extra plate at the back. Alternatively manufacture this out of steel section.

So, two tubes with a large gap between? From memory of my deflection calculations that's a far less rigid structure. The L shape is good because it resists deflection both up and down, as well as twisting around it's own axis. I think that design would perform poorly in both situations.

[Chrono]

Wow, took me 4 weeks to finally find time and gradually work on those 4 items, huh... I really need to find more time for this :D

Anyways. I did get everything in order, and took your comments into account, so let's go over the changes.
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Y-Axis Motor Mounting:
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For a long time, the only place i saw to mount the motor without it interfering with anything was below the base. This would have been achieved by lengthening the side part below the linear bearings/ballscrew. Luckily, after taking a step back and looking at the model again, I found a much better place to do so, right next to the Ballscrew for the Y-Axis itself. The spot there is pretty much perfect, since it is below any part of the Z-Axis' top part, even if the Z-Axis motor is mounted on the back, but at the same time, it is above the lowest part of the Z-Axis, meaning it does not add any constraints for the workspace inside the machine. I would plan to get those mounting plates(the green ones) cut from steel sheets, since I can get that rather cheap.

Z-Axis Motor Mounting:
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The second picture carries a lot of annotations, but I will go into the important parts again: I found two possible mounting spots for the Z-Axis motor, both are shown. Following your advice, I went for a NEMA 23 Motor on the Z-Axis, instead of a NEMA 34, like I am using for both the X- and Y-Axis. I now have the option of mounting the motor on the back, possibly compensating some of the torque the spindle places on the Y-Axis carriage. This, however, means that I need one more part to assemble the carriage, since I cannot just take two bent sheet metal parts. I would also need quite a significant amount more material, as you can see. The mounting on the back of the plate carrying the Z-Axis Bearings, would simply be using unused space that would already be there, and it would be relatively center on the axis, but possibly add to the torque of the spindle, since it is a bit forward. Using slots in the mounting bracket, I could easily change the height of the motor in that position to fit the mounting point needed, however.

I am unsure what spot to choose here. The top mounting position has quite a couple things going for it, but the back position does offer torque compensation at the price of significantly more complicated carriage assembly...

X-Axis Motor Mounting:
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The X-Axis mounting was easy to do, since I already had a good talk with one of the mechanical engineers in my workplace about that one. It is a simple Omega Belt Drive structure, driving both ballscrews from the same motor, just as you advised me to do. The two pulleys on the movable arms are tensioned using springs, not only to tension the belt, but also to increase the contact area of belt on both the ballscrew- and motor-pulleys.

Finally: The Back bearing mounting plates:
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These are basically the same as on the front and just simple metal pieces to hold the bearings of the ballscrews. The problem I currently have with them, however, is this: They are three-dimensional 20mm plates with pockets milled out of them. A better idea I had, to make them easier to manufacture, was to instead buy some longer Ali extrusion in the X-Direction, to bring the front and back edge of the machine more in line with the front face of the ballscrew-mounting-blocks, both in the front and back. Then I could use simple flat sheets of metal with some shimming underneath to equalize any tolerances. This would make those mounting brackets easier to manufacture, but add some "dead-length", when it comes to the ali extrusion, where it becomes longer, but the rails or axis are not. Still, I think that would be a better approach.
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To-Do:
Normally I would now lay-out what was on my mind, when it comes to next steps, but I cannot come up with anything concerning the CAD model, it looks pretty much done to me. What I need to now look into, however, is the electronics side of things: Find out what I still need in terms of controllers, motors, Power delivery, etc. and get some rough pricing, as well as model it into the CAD as needed. Where would be a good way to start here? For the gantry and machine design there were some helpful collection threads on here, comparing different gantry designs, for example. Is there also something like this when it comes to the electronics?

As always, thanks for any help!
-Chrono

[AndyUK]

Normally I would now lay-out what was on my mind, when it comes to next steps, but I cannot come up with anything concerning the CAD model, it looks pretty much done to me. What I need to now look into, however, is the electronics side of things: Find out what I still need in terms of controllers, motors, Power delivery, etc. and get some rough pricing, as well as model it into the CAD as needed. Where would be a good way to start here? For the gantry and machine design there were some helpful collection threads on here, comparing different gantry designs, for example. Is there also something like this when it comes to the electronics?

Suggest you start here:

http://www.mycncuk.com/threads/1524-What-size-stepper-motor-do-I-need

Once you're up to speed with the description, open the spreadsheet and customise to your needs (its setup for a smaller machine). Find reasonable values for your cutting forces and repeat for each axis in turn (increasing the moving weight as you go - ie. Z has a small moving load, Y has slightly more, X even more). I rebuilt the sheet from scratch to show all axis at once with individual inputs which helped.

Next is the leadscrew calcs - lookup typical efficiencies of the system you're using, and what each of the measurements mean. This will give you screw inertia and critical speeds. From your screw pitch, you then have your maximum permissible speed on that axis. Tailor the ballscrew configuration until you're happy with the maximum speed.

Now you have to decide what max cutting speeds and rapid speeds you want. I aimed for 5m/min rapids - some people here can get 7.5m/min. Cutting speed depends on the material (as does the cutting force).

Then you can start plugging motors into the spreadsheet. Find a few example motors online, look at their specs, and put them in the sheet taking best guesses where needed. Then play with your power supply settings, and the sheet will tell you if the motor is up to the job or not. This is how I came to the conclusion that NEMA23s on each axis were more than suitable for my application.

The motor drivers are then somewhat dictated by the current required, and the PSU is calculated by summing the maximum currents on all axes, then multiplying by a stepper usage factor (I think its 2/3rds? but you'll find this in the Power Supply threads). The voltage for the PSU is dictated by the inductance of your motors - the sheet will tell you an ideal voltage, and the drivers will have a maximum voltage - aim somewhere between those two allowing for variations in mains supplies.

Rest of the electronics are essentially personal preference. Many ways to skin a cat...

[Chrono]

I have been dabbling in the motor sheet, and found motors that would work, but i hit a couple road blocks...

The weirdest one was not finding german stores that sell steppers. I could only find one real store, that sells for okay prices, but even that one only sells to companies. The general electronics sites here, only sell steppers for horrendous prices, and only around about 10 different models max.

Another issue I was having with the sheet was the cutting forces and speeds. Is there a good summary of what to aim for, a collection thread of sorts? As it stands I am kind of lost here.

What that post also left open, is what the different types of support (like supported-supported) actually are. What would a ballscrew with its two bearing blocks count as? Supported-Supported?

On the upside, I could find motors that work for the X and Y axis (At the store that only sells to companies). This one in fact: Link (https://de.nanotec.com/produkte/568-st8918s4508-a/). Using the weights I calculated, those motors would manage to get me 7.5m/s rapids as long as the axis is 1.5m long at max, as well as 2.5m/s cutting with 50N of force, a value that i chose at random judging from the values mentioned in the post.
I did not yet look at a NEMA 23 for the Z-Axis, because of the aforementioned problems I was having with the spreadsheet.

I also attached the spreadsheet with my values, as well as another spreadsheet I used to calc the masses, so that it becomes more transparent.

Another question concerns the other electronics. At this point i am wondering what I need in total. As far as I understood, the following is needed (mostly going off of Joe Harris' Build http://www.mycncuk.com/threads/4513-3-Axis-CNC-router?p=90655#post90655):

A PSU
A Controller
A driver per stepper
A VFD
A Water Pump
A Spindle


Am I missing something here? Also, again, is there some kind of collection post of different options for this?


Now, for a bit of a curveball... The problem I am currently running into, is that I am not going to be at the company I am currently at for much longer. They do allow me to use their hardware, however, which would come in really handy, building the machine. I am wondering now, if it would be okay to start ordering parts and building the frame/gantry now, while I still have access to the tools and the mechanical engineers willing to help, in parallel to getting the electronics planned out, or would should i wait to be done with that?

I also want to take a quick second here, and really thank you for all the help you have been providing me. I don't think I could have been here without all of the assistance you provided. Thank you a lot!

[AndyUK]

Will reply with a more detailed look at your spreadsheets when I get time, but to quickly answer a couple of points:



The weirdest one was not finding german stores that sell steppers. I could only find one real store, that sells for okay prices, but even that one only sells to companies. The general electronics sites here, only sell steppers for horrendous prices, and only around about 10 different models max.

As you're in the EU, pretty much any EU store is an option. CNC4YOU.co.uk is where I got mine, Zapp Automation also seem pretty good.



What that post also left open, is what the different types of support (like supported-supported) actually are. What would a ballscrew with its two bearing blocks count as? Supported-Supported?

So here you may need to read up on ballscrews and their mountings. Free means no support (an end which is floating in mid air), Supported means on a bearing but with no axial constraint (like a BF mount), and Fixed means a bearing that can take axial force (like a BK mount). Typical configuration is Fixed-Supported, with a BK at the motor end and a BF at the other. You'll need to know this when ordering your screws, as they need to be machined appropriately.



Another question concerns the other electronics. At this point i am wondering what I need in total. As far as I understood, the following is needed (mostly going off of Joe Harris' Build http://www.mycncuk.com/threads/4513-3-Axis-CNC-router?p=90655#post90655):

A PSU
A Controller
A driver per stepper
A VFD
A Water Pump
A Spindle


Am I missing something here? Also, again, is there some kind of collection post of different options for this?

Oh wow. Theres like a billion different options. Finding a path is tricky! Ultimately, you need some way to turn GCode into motion.

That often starts with a PC sending the Gcode to a parallel port - but PC's aren't great at realtime and they're not often made with parallel ports these days, so some kind of motion controller is often used to simulate a parallel port and deal with the realtime aspect. Recommend ethernet variety. Then you may or may not need a breakout board depending on which controller you use - a UC300eth for example just gives you five headers with lots of pins, its nicer to have a board like the UB1 attached to output all those pins nicely and deal with a few other things like relays.

Next, the controller sends off pulses to the drivers. Depends on the motors you choose, but the Leadshine AM882/EM806s are popular around here. Nice to have a decent current range and voltage range that are applicable to your motors, and missed step protection is nice. As you point out, one driver per stepper.

PSU to power the drivers. Calculate the right voltage and current, then size appropriately. Some folks like Joe build their own, its not too hard. Other PSUs will be needed for the sensors and auxiliary components, you'll have to draw up a diagram to figure out what you need. Typically a 24/12/5V, or maybe even multiples.

Spindles and VFDs often bought together from China. Recommend ER20 or ER25 for the larger tooling. Water cooled will be a lot quieter. Some even come with a pump - to be honest, it doesn't seem like the cooling requirements are massive, an aquarium pump will probably do.

Other electronics - Circuit Breakers, Contactors, Switches, Relays, loads of wire, Limit switches, Home switches, fans.... the list is endless. Don't forget software, and somewhere to keep all these expensive electronicals.



Now, for a bit of a curveball... The problem I am currently running into, is that I am not going to be at the company I am currently at for much longer. They do allow me to use their hardware, however, which would come in really handy, building the machine. I am wondering now, if it would be okay to start ordering parts and building the frame/gantry now, while I still have access to the tools and the mechanical engineers willing to help, in parallel to getting the electronics planned out, or would should i wait to be done with that?

Up to you. If that was my situation I'd probably be making a start while I've got the opportunity to utilise the expertise, but be prepared to backpedal slightly more than if you've got a plan sorted from the start.

[Chrono]

More progress, at least in the design department!

I did decide to design out the Z-axis a bit and plan on how to build it up, especially since one of my coworkers asked me the fateful question of: "Well it is technically possible to manufacture, but are you sure, that you can actually put it together like that, when it is in front of you?". With the earlier draft, I have no idea if that would be possible to actually assemble without a huge hassle, so I thought about it and came up with a better design, using screws and bent steel plates. The pink plate I will probably be changing out for a thicker aluminium one. Also something of note is that the bends and such are not accurate. I simply don't have enough time in Fusion's Sheet metal work-space, so I just went with the default settings for convenience's sake. After taking another look at your machine, since I was asking myself how to get more length out of the Z-Axis, I will probably also switch the rails to be on the sled and the bearing blocks to be on the gantry, like you did.

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I also changed the size of the machine in my Fusion design to reflect my "updated" plans for size. This broke a couple things that I did not yet get around to fixing, like the floating plates and angles, as well as those two Z-Axis bearings floating in the middle of nowhere. The original size was guesstimated around 1m x 0.8m x 0.2m while I was still messing around with the base design. The "new" size I plan on having is: X: 2m, Y: 1m to 1.2m, Z: ~0.3m to a max of 0.5m. I am not quite sure about what a good measurement for the Z-Axis would be, so if there are any values that have generally found agreement in what not to exceed, let me hear it :D

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For the linear motion setup, I am planning to use Chinese 1610 Ballscrews (https://de.aliexpress.com/item/32869293159.html) and HIWIN-style rails (https://de.aliexpress.com/item/32883002950.html?storeId=4053076&spm=a2g1y.12024536.productList_13589487.subject_2) (note: not original HIWINs). The reason for that is that I started pricing out the build to where I now have a pretty "final" (well, as final as it can be at this stage) price for it, bar the uncertainty of import tax and the like. All in all this puts me at around a 3k € to maybe 3.5k € total, if taxes end up really high, and of course, planning in a cushion in case something goes wrong. The difference of the Chinese rails to the original ones is quite significant in that, however, with the bundle of ballscrews, ballnuts, BK and BF blocks, linear rails and slides, being 50% more expensive, when using original rails, with all other things being constant. But I still have to ask: Are those rails okay to get, or are there any known problems with them, accuracy-wise or otherwise?

I have also checked these lengths in the motor calc spreadsheet, and with the 2m axis, I would now be down to 5.2m/s rapids from 7.5m/s. Should I reduce this to get back up, or should I be keeping it? My reasoning for going as big as possible, is to get the "best value", so to speak. I don't want to be caught standing there with my pants down, when a project requires me to have big machine. Alternatively I could also go with 2010 ballscrews and up-size my stepper on the X? I might need to properly calculate the increase in price for that out.

Another thing that caught me off guard is just how much the motion controller, and especially that breakout board cost! 300€ for a control board and its breakout sound properly astronomical to me :D But alas, I also know not to skimp on the important bits.

With the leadshine drivers, and a spindle, that should nearly do it for electronics. Speaking of spindles, however, I was looking at this 2.2kW one. (https://de.aliexpress.com/item/32871507893.html?storeId=4053076&spm=a2g0x.12010612.8148356.1.1dba3959qSHzhJ) Is 2.2kW a good amount of power for my uses (wood, plastics, some aluminium, PCBs)? They also do carry a 3kW model.

Regarding Sensors, so far I have only been able to think of Endstops and homing switches. What else would I be needing? Another question that was on my mind, is why I need homing switches? Does the "home" need to be different from {0,0,0}, or am I missing something here?

You also mentioned software in your post. I know of Mach 3 and I also saw that they now make Mach 4. Are there any others out there, or are these ones the ones to get?


Now, on a completely new note: I have finally taken into account that I still need a table. I have chosen to keep this one on the back burner for a bit, until I got a preliminary pricing done for the machine itself, and I am now considering how to do this. Most machines I have seen so far, are using a steel table, that even reaches above towards the Y-Axis, where I have those big plates. Since I am using aluminium profiles already, I was thinking that I could just buy some more and make the table out of that. This would also allow me to slightly redesign my machine and allow for a similar design like yours, for example, with the raised sides. I am guessing that would be a huge plus in terms of rigidity, compared to my steel plates approach? I would, of course, loose some access and some space on the sides, accounting for the width of the extrusion, but with how wide the Y-Axis sled is, that should not be a problem in terms of actual cutting width loss, if executed correctly.

[Clive S]

I have also checked these lengths in the motor calc spreadsheet, and with the 2m axis, I would now be down to 5.2m/s rapids from 7.5m/s

You could also think of using rotating ball nuts :calm: 2Mtr is a long way with 16mm screws

[Chrono]

You could also think of using rotating ball nuts :calm: 2Mtr is a long way with 16mm screws


How would I mount the rotating nuts? I guess I would need the motors on the gantry then? Would that also mean that I would either need an elaborate timing belt setup spanning the gantry, or use two motors?

I can also just use 2010 or 2510 ballscrews and get a stronger motor for the X, which is something I am actively thinking about. According to the motor calc sheet, the Y and Z are perfectly fine as is, at 7.5m/s rapids, using 1610 ballscrews.


On another note: After thinking more about the changes I talked about and talking them, and other things, over with my colleagues, I am remaking the CAD file from scratch. While doing that I am also reworking everything to be 100% parametric, which is taking a while, but is paying off massively. Basically fixing mistakes made the first time around.

Current progress is the following: The table and X axis are done, except for the X axis ballscrews. The Gantry and Y axis are complete. What is yet missing, is everything concerning the Z-Axis, pending a complete revision, Motors and timing belts, and E-chains, that I want to account for. All in all, it is progressing nicely.

26021

[Chrono]

Hey everyone! More progress on the redesign. I sat down and actually worked on it everyday this week, and got some real progress done, finally. I am much more satisfied with how that one turned out, compared to the old one. Here is a side-by-side:
2604326044

It is probably obvious, but the old one to the left, the new one to the right. This will be the convention for pictures for the rest of the post as well. (On a side note: The blue extrusions are going to be changed from 45x90 ones to 45x45 ones, to save money. I just have not gotten around to fixing them in CAD, since they were pretty low on the list in terms of priority)
While being at it, I also changed a whole couple of things: Like the Z-Axis

26045 New: 2604626047

The Z-Axis got completely changed. Where it was a complex part before, it is now a rather simple bent sheet steel piece. The motor is now also affixed to the Z-Axis itself, and is moving with it. This is to keep the Gantry-side Y-Axis sled small. It also theoretically means, that I don't need to change anything but the Z-Plate, the rails and the Gantry sideplates to add more Z-space later on, if I ever decide on it. All in all, I like the design change of putting the bearing blocks on the Gantry sides, and the rails on the Z. Allows the parts to shrink a bit. That is one design change I picked up from AndyUK's build. The Ballscrew is also mounted on the moving Z-Axis, with the Ballnut being fixed on the Gantry Sled. One question that I still have, however, is how the cutting spindles actually get mounted to the Z-Axis. I understand that the spindle itself is mounted in the red aluminium ring, but how is that ring mounted? None of the pictures I could see in the offers showed any mounting holes. Are you meant to drill those yourself?

The Gantry itself got a revision as well!

26048 New: 26049

The obvious thing is probably the size and shape change. I went from an L-Assembly to a C-Assembly. This is so that I could move the rails up front, which should not only give me more rigidity overall, but also allowed the massive simplification in assembly for the Z-Axis and Y-Axis Sled. This is one change I really took a liking to.

Something that was not quite obvious from the last post, but was already in it, is that one of the side plates fixing the gantry beam to the X-Axis is much thinner than the other one, in this case the left one is thinner (3mm of steel) than the right one(10mm of steel). This is to give the machine a way to have a bit of play, should something not be fully aligned, and off by a tiny bit. Another measure to the same effect has been brought up by my colleagues multiple times now: To only put linear rails and bearing blocks on one side, and have the other only constrained against translation/force, not torque, and we finally came up with a workable example, I want to discuss here:

2605026050

Let me explain. The plan would be to put the second linear rail on the lower extrusion on the right (looking from the front of the machine), and have both of them on the same side. Then, instead of a rail, have a supported smooth steel rod, and a cylindrical type round linear bearing on the left side, to replace the rail. That way, the linear bearing still constrains the movement on the translational axes and takes on the forces, but it would permit torque, which would fix the problem with it being statically overdefined. What do you guys think of that? None of the Logs and posts I have read here, so far, have reported any real problems with any of this, but one of my colleagues who has had contact with similarly built machines, with a different purpose (cannot exactly remember) is bringing it up as the thing they and their competitors did, to avoid problems in the same vein. And looking at the budget, one rail with linear bearings should not be the point that bankrupts me here :D

Another question I am having is regarding the long ballscrews on the X-Axis and the motor calc sheet. As discussed way earlier in this thread, I want to stay with a single stepper for the X axis, even though I have two ballscrews, linking them with timing belt. Now my question is, in the Calc sheet, don't I need to input a "times two" into the calc of the torque needed to spin the ballscrews, since the stepper needs to drive both of them at the same time? Since I want to go to 2010 or even 2510 ballscrews, that is one hefty variable to think about. From my initial messing around, I can either go less fast with a 2010 ballscrew (Around 6.3m/s rapids) with a weaker stepper, or find a much stronger one to drive the 2510 ballscrew at the full 7.5m/s rapids. Of course, cutting is another thing entirely, and I am still not quite sure what speeds to aim for here, but for reference, I have managed to get around 2.5m/s with 50N of cutting force, in my testing. Another way would be to stay with 1610 ballscrews and scale the X down from 2m to 1.7m, but that is something that I only want to be doing as a last ditch effort, so to speak.

And another on the ballscrews: Would I just mount normal timing belt pulleys to them, to connect them to the motors, or would I need special machining or parts here?



Regarding the Electronics: other than the Steppers, I have also been looking at all the other electronics. And I think I have it down to the following:

X-Axis Stepper: Still looking
Y-Axis Stepper: ST8918S4508-A
Z-Axis Stepper: ST5909M2008-A
Stepper Controllers: Either Leadshine AM882s or EM806s times three, after AndyUK's recommendation, still trying to figure out the exact differences there.
Controllers: Either the UC400ETH or the Smoothstepper ESS, although I am still dabbling about the electronics section of the forum. I don't think that I will be getting breakout boards, since I can easily deal with electronics, and just soldering the proper cableing sound much more reasonable to be, instead of buying a 130 pound breakout
The VFD will likely be a YL620-A packaged with a chinese 2.2kW watercooled spindle, alongside a water pump
And finally: six microswitches for end stops. A thought here: would there be any profit had from using proximity switches?


Regarding the choice of controllers: I had a quick dabble with the Mark 4 demo, and as I understand, it is pretty much indifferent to the exact board I choose, and the board itself does also not really need to be wired up in any special way, since I set all the necessary port/pin assignments in Mach 4 itself (granted that I match input pin to input, output to output, etc.)?

When it comes to schematics: I just installed AutoCAD today to get something done, and thankfully I have got some people with a background in high-power electrical installations to help me with the cabinet and all the safety measures needed. After I have everything in there, I can think about all the PSUs needed.


All in all, I am really satisfied with the progress had in a week's time, and I am constantly working to finally get to the point where I am comfortable with the end result. If anyone spots anything that seems off with the revision, however, I would be very glad for any criticism on it. Ultimately, the more eyes and voices are involved, the less likely that mistakes fall through the cracks. And to that effect, here is the link to the web interface of Fusion, where you can take a look around the newest, up-to-date version of the 3D CAD Model yourself, and take a closer look. (https://a360.co/32tPvuo)

On the note of getting a lot of feedback, however, I am noticing that other post here get a lot more traction, when it comes to user response. Don't get me wrong, I am by no means meaning do downplay the contributions made my AndyUK, CliveS and Washout(Who literally brought me here), you guys are the reason I have comes this far, and I cannot thank you guys enough :love_heart:, but at the same time, I am wondering if my post broke etiquette, or if I did something else, that made people not want to engage here? Because if that is the case, I would like to work on fixing that.

Anyways, I am already staying up way too late to finish up this post, so I am just gonna end it here and head to sleep.
Thanks,
Chrono

[Washout]

Hi Chrono

No broken etiquette as far as I know. You're probably doing a great job and nobody has much more to add ;)

A few comments I would have from your last set of design drawings are:
- whilst 4 rails looks like a good idea, you will have a devil of a time aligning them I expect. Maybe 2 rails of a larger size might be better?
- Also consider the CS-Labs kit for the controller - many on here use them, including the venerable JazzCNC (which is always a good sign imho)
- Proximity switches if they are the type in a threaded housing, will give a nice amount of adjustment for the trigger point - you can do the same with micro-switches, but they then need a plate with slots to mount them to to achieve that

Keep going and I expect interest will pick up once you start building :thumsup:

[AndyUK]

I'm still aware I haven't gone through your calcs yet... Finding time is hard! Sounds like with the design changes though I may wait a little longer :)

I second Washout's comments about the CS labs stuff, looks brilliant. The thing that put me off was that the base model is only 4-axis, and it doesn't handle slave axis homing native-ly (although there are decent workarounds posted on here). Anything more than the base model is horrendously expensive, and I wanted future expand-ability to add a 4th axis which is gone if you use the 4th for a slave - but you avoid both of those issues by having a connecting belt and single motor.

Also, on the four rails idea, I think you'll definitely end up spending a few days becoming best mates with your dial gauge - but it could pay off in the end?

First impressions on the redesign; I think your CAD is coming along nicely, really shows. I do have a few concerns though:

I question the Z axis travel length and why the plate is so large - Don't forget you'll have a bit attached to the end of your spindle, and its going to have to be quite a long bit to make use of your Z travel. I've got 18cm, and honestly, its probably far too much, most of the time you're really only needing to cut say 18mm plywood! The distance between the bed and the gantry looks huge - All that Z extension reduces the rigidity of the machine. Have a think about what you really need - can it be acomplished in other ways, such as an adjustable height bed or overhang section which keeps everything stiff for the majority of the time, but when you need to use the router on something large you can?
How are you going to assemble the Z axis? Look through the design, building it up step by step, and imaging when you will or won't have access to each screw and what that implies. I've got my ballscrew and motor on the fixed bit because I can easily get to the four screws holding the ballnut onto the Z plate, undo them, then slide off the rails. Your design looks a little harder to physically assemble.
The C beam - how are you going to attach those profiles to each other? Any weakness here will be quite problematic and you've got two joints which need to be constrained.
10mm of steel looks quite beefy for a side plate, but 3mm seems quite weak in my head. I realise its intentional, I'm just not convinced!

[Chrono]

A few comments I would have from your last set of design drawings are:
- whilst 4 rails looks like a good idea, you will have a devil of a time aligning them I expect. Maybe 2 rails of a larger size might be better?



Also, on the four rails idea, I think you'll definitely end up spending a few days becoming best mates with your dial gauge - but it could pay off in the end?

It seems I have messed up my explanation here. I do not plan on using four rails, but instead three. Two linear HIWIN-style (https://de.aliexpress.com/item/32869293159.html) rails on one side, mounted atop each other. The other side only has one rail, and a different type, namely the cylindrical Igus-Style (https://www.igus.de/product/736) rails that you also often find in 3D printers, like the Prusa MK3. That will still take some work aligning, I get that, but it should technically work to help let the machine compensate. I know, technically is a nice word, but practically often takes precedent :D I have added another picture, with the HIWIN rails in their place, to hopefully make that more clear.

26060




10mm of steel looks quite beefy for a side plate, but 3mm seems quite weak in my head. I realise its intentional, I'm just not convinced!


This one's along the same vein, and it honestly also seems off in my head, but the math should check out there. Ultimately, the sideplates don't cost much to make, especially not the smaller one on the left, so if it turns out to be a problem, I can change it around without much of a problem.




First impressions on the redesign; I think your CAD is coming along nicely, really shows. I do have a few concerns though:
[LIST]
I question the Z axis travel length and why the plate is so large - Don't forget you'll have a bit attached to the end of your spindle, and its going to have to be quite a long bit to make use of your Z travel. I've got 18cm, and honestly, its probably far too much, most of the time you're really only needing to cut say 18mm plywood! The distance between the bed and the gantry looks huge - All that Z extension reduces the rigidity of the machine. Have a think about what you really need - can it be acomplished in other ways, such as an adjustable height bed or overhang section which keeps everything stiff for the majority of the time, but when you need to use the router on something large you can?

Something like that came up when talking to my colleagues as well, today. We came up with inserting angles to hold up the sides, which could be removed if needed, but when there, would make it a bit stiffer. I really quickly added one in the picture above, highlighted in pink. Imagine four of those in the corners.
Could you maybe elaborate on how an adjustable Height bed and that "overhang" would work? I have a hard time imagining those two.




How are you going to assemble the Z axis? Look through the design, building it up step by step, and imaging when you will or won't have access to each screw and what that implies. I've got my ballscrew and motor on the fixed bit because I can easily get to the four screws holding the ballnut onto the Z plate, undo them, then slide off the rails. Your design looks a little harder to physically assemble.

Good shout! On the first look, I should be able to do a similar thing, but with removing the screws of the Z-Ballscrew Bearing Blocks instead, but I will definitely check that again.



The C beam - how are you going to attach those profiles to each other? Any weakness here will be quite problematic and you've got two joints which need to be constrained.

I have enough space between the screw and the profiles, to be able to insert some angles to bolt them together (that is going to be some fun fiddling with angled hex drivers, however :D) and I can also bolt them together on the back side as well. With the sled in front, forming a closed frame and additional bolts in the side-plates, that should be enough then, right?



- Also consider the CS-Labs kit for the controller - many on here use them, including the venerable JazzCNC (which is always a good sign imho)



I second Washout's comments about the CS labs stuff, looks brilliant. The thing that put me off was that the base model is only 4-axis, and it doesn't handle slave axis homing native-ly (although there are decent workarounds posted on here). Anything more than the base model is horrendously expensive, and I wanted future expand-ability to add a 4th axis which is gone if you use the 4th for a slave - but you avoid both of those issues by having a connecting belt and single motor.

With that much of a recommendation, I will definitely take another look. But I must admit, the price of the units, especially compared to the other controllers is quite steep. I might just stick with one of the cheaper ones and maybe upgrade later on. I am managing to stick within my initially laid out budget for now, but I want to also reserve a buffer in that, so that a problem won't throw me off course completely.




- Proximity switches if they are the type in a threaded housing, will give a nice amount of adjustment for the trigger point - you can do the same with micro-switches, but they then need a plate with slots to mount them to to achieve that

Yeah, that was my thought. My 3D printer uses a proximity switch for leveling, and needs exactly that adjustment, which also means that it can be calibrated pretty finely.




I'm still aware I haven't gone through your calcs yet... Finding time is hard! Sounds like with the design changes though I may wait a little longer :)

Don't worry, no rush :D I am pretty sure I have suitable Y- and Z- Motors, but the X-Stepper is what I am still fiddling with the spreadsheet for. My main problem is how to calculate the thing driving two ballscrews at the same time. I just added a multiplication by 2 in the part of the equation that contains the Screw Inertia.

[Chrono]

While I am busy getting all the detail into the CAD and making sure all the dimensions are correct, a question came up, that I want to ask the collective of experience in this forum.

This question is, if I can use the chinese linear rails (like these (https://de.aliexpress.com/item/32869293159.html)), or if there are any known problems with their accuracy or surface finish that makes them bad alternatives? I am asking this, because of just how much cheaper they are to get. Same question goes for the ballscrews. (https://de.aliexpress.com/item/32883002950.html?storeId=4053076&spm=a2g1y.12024536.productList_13589487.subject_2)

[MartinS]

Hi Chrono


It seems I have messed up my explanation here. I do not plan on using four rails, but instead three. Two linear HIWIN-style rails on one side, mounted atop each other. The other side only has one rail, and a different type, namely the cylindrical Igus-Style rails that you also often find in 3D printers, like the Prusa MK3. That will still take some work aligning, I get that, but it should technically work to help let the machine compensate. I know, technically is a nice word, but practically often takes precedent :D I have added another picture, with the HIWIN rails in their place, to hopefully make that more clear.
26063


When I first saw this design, I couldn't help but think that was far, far too flimsy

Now with your explanation of the gantry driven from one side only (above)......it's getting worse!

Don't forget that to reduce cutter breakage, wear, chipping, improve accuracy and surface finish, the whole machine must be as rigid as possible and subject to as little resonance and vibration as possible. This is why machines traditionally are made in cast iron or synthetic granite (Granitan etc) that are "dead" materials, they don't "ring".

In the latest design, you are driving the gantry from one end only (and I still can't understand what the benefit is of the lower ballscrew). This goes against evrything that you will read on this forum, "ballance your forces", " place the cutter forces in between the bearings" etc. It is akin to digging a hole in the garden whilst standing on a diving springboard!

And the 6mm thick gantry sideplate.......

Compare yours

26063

with this from Boyan.

26062

Yup, Boyan's is built like a brick sh!thouse. Some may say that it's over the top, but I bet it does the job!

Or just taks a look at Andy's build

http://www.mycncuk.com/threads/11552-AndyUK-s-Build-1-2x1-0m-Gantry

Sorry if I seem somewhat hard on you but I don't want you to waste time and money unnecessarily.

Any other of you forum guys have a comment?

Good luck Chrono, you'll get there.

Martin

[Chrono]

Hi Chrono



When I first saw this design, I couldn't help but think that was far, far too flimsy

Now with your explanation of the gantry driven from one side only (above)......it's getting worse!

Don't forget that to reduce cutter breakage, wear, chipping, improve accuracy and surface finish, the whole machine must be as rigid as possible and subject to as little resonance and vibration as possible. This is why machines traditionally are made in cast iron or synthetic granite (Granitan etc) that are "dead" materials, they don't "ring".

In the latest design, you are driving the gantry from one end only (and I still can't understand what the benefit is of the lower ballscrew). This goes against evrything that you will read on this forum, "ballance your forces", " place the cutter forces in between the bearings" etc. It is akin to digging a hole in the garden whilst standing on a diving springboard!

And the 6mm thick gantry sideplate.......
Martin

First up, I am still driving the gantry on both sides. Just one side is resting on two HIWIN rails, while one is resting on a linear bearing on a smooth steel rod-type rail. Here is the model if you want a more detailed look. (https://a360.co/32tPvuo)

Secondly, I appreaciate the feedback, but what exactly are the problem areas here, what needs to change? Most design decisions come from advice I got from the mechanical engineers at my place of work, some of which have been building similar highly-dynamic gantry machines for Zeiss, taking measurements. This is also where the rail division comes in. Looking back at my technical mechanics textbook, this should protect the linear rails from having to take on torque, while still handling static loads. So that is the reason why. I, obviously, cannot tell you if that will work or not, but that is why I am here, after all :D

Edit: Some pictures to illustrate the whole X-Axis setup, excuse the dreadful mouse-written writing.

2606426065

Another constraint I am having, is that steel box section, for example, is pretty difficult for me to work with. I do have access to people who can weld for me, etc., but I pretty much have no way to assemble the machine where I need it to, in my workshop, or get it out of there, once assembled. It is on the first floor in my garage, with the only access being a small staircase barely wide enough for one person. Hence the aluminium profiles. If that is a no-go, the only other option i have, is a small hatch, not even high enough to kneel in, which will severely limit the machine's size, overall.

Then there is also my budget, which is pretty close to being used up, even with that design.

On a side note: do you have a link for the post from boyan? I would like to further read up on that build.

Thanks for the feedback,
Chrono

[MartinS]

First up, I am still driving the gantry on both sides. Just one side is resting on two HIWIN rails, while one is resting on a linear bearing on a smooth steel rod-type rail. Here is the model if you want a more detailed look.

Chrono, apologies for missing the second ballscrew, that makes a big difference. You at least have a brick under the end of the springbard:thumsup:

Most builders here use rails both ends of the gantry to as best they can, constrain "flexy" elements (don't forget, most materials are looking for any excuse to bend, twist or vibrate).

26070

When your spindle is cutting at the 6mm plate end of the carriage, Hiwin rails will help resist the twist on the gantry better than the Igus ones. And either way, increasing the distance "C" between them will help.

I mentioned Boyan Silyavski's build
http://www.mycncuk.com/threads/6457-Sturdy-and-Fast-all-Steel-CNC-my-first-build
not to push you towards steel, Al is fine, but to demonstrate by design, reducing the chance of flex and vibration.

Re. the 6mm gantry end, I think that you mentioned that it is to "...let the machine compensate". I guess that you mean "to accommodate assembly/build errors" One way that others achieve this with rigid side rails and substantial side plates, is to mount the Hiwins on the top so that with clearance holes in the sideplate mounting, they can find their own best position on the carriages. See AndyUK's approach. Again, I am not pushing you to change, just showing other approaches to your best friend "rigidity". Also, bracing across the end is another approach.

26071

I have a background in manufacturing with machining centres and lathes with capacities up to 1200mm, precision grinding and measuring with CMM's in controlled environments. Whether it be a CMM or a cutting machine, we want to be assured that the probe or cutter is in a specified and known position. The difference betwen the two are the forces in the system. Those in a cutting scenario being far greater....

Regarding the side rails, it wouldn't harm if you added one or two extra pillars and fillets per side. Also, bracing across the end is another approach.

26073

I hope that this post is more positive than the last one. There are soooo many ways of getting "there" and you are nearly there, Y and Z look great.

Crack on lad......

[Chrono]

That cleared things up a lot, thanks! I gotta admit, for a second there I thought the aluminium profile construction was "out of the question" entirely, so to speak, so I am relieved on that end :nevreness:

I also thought about putting in some more support pillars, so I will do that. They are so short anyways, that they don't cost enough to not put in. regarding a crossbar, I could easily put one in in the back, without even impeding X travel, since the gantry's body will sit on top of it, and it will run out of rails before the spindle would even get a chance of touching it.

You also put in angles in the middle pillars. I definitely see their point, but I am looking at them protruding into the machining area, so I might try and make them removable, with accessible screws, so I can put them there for smaller projects, and take them off, when I need the space. That way I get the best of both worlds, so to speak.

Also, regarding the distance between the bearing blocks on the X: That is one of the parameters I can just change on-the-fly, so changing that is easy-as-can-be :D I am mostly leaving it as a kind of place-holder while I am working on getting everything into place. Afterwards I just need to open the variables panel, and go to town dialing everything in.

Finally, on the topic of the thin plate, and the associated double-stack of rails, with one opposite linear rod bearing: It is not that much about building tolerances (I mean I am not perfect, so there will be those), but also things like thermal expansion, and so on. I am going off of the one lecture in mechanical engineering I got in my electrical engineering course, but with the linear rails on both sides, you would enter statically-overconstrained territory, which is exactly the reason for me to go for the steel rod and linear bearings, exactly because they cannot take on torque. however, if this ends up not panning out, changing the lower rail over, would be quite easy, since all i would have to do is cut down the gantry extrusions by 7mm (which the linear bearings are higher by, compared to the rails and bearing blocks), or shim it with another plate, and swap in one of the rails, not a big hassle.

And I found a picture of the Zeiss machine I was talking about: 26075

As you can see, it has a similar design, with rails on existing on the right, while the left either rolls on the table or hovers on it, I cannot remember if the hovering was another machine, though, and a quick search did not throw up any info. Either way, looking at the YZ-Plane, one end is fixed, while the other is allowed to expand/move. Of course, that does not mean that it works the same for me, but I thought I would post that for illustratory purposes :)

I also plan to add some slits in the plates themselves, serving as holes for potential cross-supports, should it turn out that they are, indeed, too bendy. I will attach a picture hereafter, looking at the right plate, with such a support in vibrant pink. I am afraid that picture can explain this much faster than I could in words. Those plates should serve to add further rigidity, in the same sense as the bends all around the Z-Axis do, and if I find I need them, I can put them in, weld them in place, and go from there.

26074

(also seen in the picture, in the front left of the machine, the WIP of new angle plates. The right is not in yet, because I still need to move the right ballscrew vertically in between the two rails)

What do you think of those measures to address these problems? Is there anything else I should be doing to increase the rigidity?

[MartinS]

You're planning to beef up the side rails, add the bed whilst you're at it.

Much advice has already been given to you and there is sooo much more on this site from some VERY talented, knowledgeable and experienced people :

http://www.mycncuk.com/forums/253-DIY-Router-Build-Logs

Don't get too hung up on the design of CMM's.

Time you put a new blade in your hacksaw!

[Chrono]

You're planning to beef up the side rails, add the bed whilst you're at it.

Much advice has already been given to you and there is sooo much more on this site from some VERY talented, knowledgeable and experienced people :

http://www.mycncuk.com/forums/253-DIY-Router-Build-Logs

Don't get too hung up on the design of CMM's.

Time you put a new blade in your hacksaw!

I have to completely agree, without all the advice from the people here I would not even have remotely come this far!

Currently I am reading through some of those build logs to hopefully find a good one about the PSU section of the build. All the electronics are pretty clear to me, but the interface between machine voltage and net voltage. I see that a lot of people build their own transformers, which is definitely an option, but I am still looking into that. Most of what I am still missing on the machine side mostly related to the spindles and which I want to have in hand, before commiting there.

If all goes to plan, I thus want to sort out the electronics over the next two weeks and then move on to buying parts. That is when I want to make a final pass and move on to the next step, if there is not a flaw that needs sorting out. Once I do move on to buying, I will probably make a proper build-log post as well.

I am also scouring the posts for something related to cutting forces and speeds, to be able to dimension the steppers. As far as I could gather from various posts here, I would pretty much always like to use the steppers in bipolar parallel connection, and using that, getting all the info and all the steppers I can find, I have not found a single one, so far, capable of driving two 2510 ballscrews at 7.5mm/s rapids... who would have thought? :D So I am thinking about moving to a one-stepper-per-screw setup. With that, however, I am still looking at one of AndyUK's first pieces of advice to me and hesitating. So I am thinking about putting a timing belt between the two motors to synchronize them as well, but I don't know if that is a good idea or if it even works. Looking at the motor calc sheet, however, there is a motor that would permit me to get 6.1m/s rapids with only a single motor, as well as letting me cut at 2.1m/s with 50N of cutting forces. But then again, I am still searching for posts on speeds to look out for.

[Chrono]

Long time no post, was busy these last couple weeks, but I am finalizing the build. Pretty much everything is done, except for the timing belts and the electronics layout.

I solved my motor problem by simply shrinking the machine to a tiny 1.8m on the X-axis. This allows the use of the smaller 2010 ballscrews, and, in turn, a single motor.

Other than that, I have been verifying dimensions and hole placements and been putting in manufacturer CAD files for all the rails and screws. I have been putting together some angles for the inside (the yellow one in the left side of the machine in the picture) that I can remove if I need the width and otherwise keep in. Since the CAD file already takes ages to change anything in, I only put in one, to keep the computation time down a bit, but the plan is to have two per column.

I guess I only have 4 questions left:
1. I have seen that people usually use transformers for their steppers, and I understand that that is because regulated PSUs may have problems with the current spikes (at least according to the app notes). I could not find a proper post on how to do it on here though, so If anyone has a good source on that, that would be perfect.
2. How do people usually tension their belts? I am still trying to figure out where to place my tensioners.
3. Where do you even get belt long enough for something like this, and what type of Belt? Using a manufacturerer's tools, I have been able to calculate that my belt would be approximately 4.8m long, for the X-Axis. I have not found closed-loop belt in that size yet.
4. Is there anything you would still change in the design? When I say finalizing, I mean that I am compiling prices and sources for my parts, and ready to pull the trigger whenever I am done and move this over to the build-log section, so this is the "final chance" to change anything, so to speak.
26188261892619026187

As always, here is a web browser accessible version of the model if you want a more detailed look. (https://a360.co/32tPvuo)

[AndyUK]

1. I have seen that people usually use transformers for their steppers, and I understand that that is because regulated PSUs may have problems with the current spikes (at least according to the app notes). I could not find a proper post on how to do it on here though, so If anyone has a good source on that, that would be perfect.

My build thread, post number 30 has an outline of the process I followed, but I emplore you to find multiple independent sources of information and fully understand and verify before playing with a mains level PSU - this is the scary bit of the project to me, because one slip can potentially kill. Always ensure the caps discharge and never work near the PSU whilst alone in the room. I've have given the wife very clear instructions on how to isolate the supplies if it goes wrong. ALWAYS have a bleed resistor - it's not something I mentioned in my thread, but it's a must.

Scary bit over, it's not that hard or expensive. You just need to stay safe.

As for information, I didn't find a definite thread here, probably for good reasons. You're going to have to go research the theory of unregulated PSUs. Joe's videos are also quite good at explaining, and so are ThisOldTony's CNC build videos.



Sent from my SM-G950F using Tapatalk

[Kitwn]

There's a nice guide to designing linear power suplies here http://www.skillbank.co.uk/psu/

Whilst it's true a linear supply of a given rating can deliver significantly higher current peaks than a switch-mode supply of the same rating, you should look at the relative cost of a linear design and a suitably rated switching supply or possibly two separate supplies, one for, say, two motors on X and one for the single motors on each of Y and Z.

I can't see the point of spending a lot of time and money on building an unregulated power supply which can, even briefly, deliver far more current than is required to saturate the motors. The available current in case of a fault would also be much higher.

Kit

[Clive S]

Have you seen Joe Harris build log here is a link to his youtube channel on power supplies https://www.youtube.com/watch?v=4OoQQg76ar4&list=PL1FIADAKba_tiLqXbUkzD30sZjtp_VyqY&index=2&t=0s

[Chrono]

Hey guys! Sorry for the radio silence, I had hoped to be able to post a finished schematic, but mine and the person helping me with that part's schedules just did not meet up yet, so that has not come to fruition yet.

So first up, thanks to all the tips for the PSUs. I think I have a firm grasp on the matter now.

Instead of a schematic, I worked on finalizing the budget and getting everything priced out, and so far, the only thing missing from the budget are timing belts and the control box parts (like contactors, etc.), but so far, everything is savely in my 3.5k€ budget, even with a couple hundred of wiggle room. So, since I have not posted this before, I "present" the semi-finalized list of electronics to be used:
A smoothstepper ESS. From all the controllers I have looked at, this one seems to have the highest price/performance ratio. Compared to the UC400eth, for example, I get one more port for a similar price point. And the CSlabs are just too expensive for me, in comparison.
A 3kW watercooled chinese Spindle with ER20 collets, able to reach up to 24 000 RPM with a packaged submersible pump
A YL-620 VFD for that spindle
AM882 Stepper drivers for all three steppers, supplied with around 60V
X-Axis Stepper: 86 HS155-5508-01
Y-Axis Stepper: ACT 34HS1456
Z-Axis Stepper: 60BY G401-03
6x Inductive Proximity switches to be used as Limit/Homing switches


Other than that, not much has changed on the mechanical front: I have had a two parts re-drawn in a different CAD program by someone well-versed in designing sheet metal parts, but other than that nothing has been altered. I hope to be able to get the schematic done in the short term rather than the long term, so I can finally move this to the build log section ;) Anyways, until I have more news!

[JAZZCNC]

Hi chrono,

Wouldn't go with ESS as the backup is rubbish and your limited to mach3/4. The uc330eth or 400 are both much better options.

I've not read all your thread but i saw you where struggling regards ballscrews and sizing them. So here's a suggestion which might help that I've built many machines using.
Use 2020 with 2:1 ratio. This gives same speed as 10mm pitch but halfs the screw speed so less chance of whipping screws. It also doubles the torque from motors.
Also very easy to increase velocity if needed by changing ratio.

Next suggestion is to buy drives that accept AC then you only need to buy transformer. That said building toroidal DC psu isn't difficult and don't let anyone tell you different but they are the best type for Cnc machine that moves quickly with high speed directional changes like routers make where drives have to handle dynamo affect of steppers.



Sent from my SM-T580 using Tapatalk

[Chrono]

Hi chrono,

Wouldn't go with ESS as the backup is rubbish and your limited to mach3/4. The uc330eth or 400 are both much better options.


Understood. I've been scouring the forum and the web, but it seems my search-fu is a bit off, since I could not really find a conclusive answer on the differences of the UC300eth, UC400eth and AXBB-E, especially since CNCDrive's web pages are kind of scarce on the matter. As far as I am able to see, the 300 just has more IO than the 400, withe the AXBB-E has the same amount of IO as the 400, but a built in Breakout in a nicer package? Judging from this post (http://www.mycncuk.com/threads/11808-Any-USB-Ethernet-controller-suggestions?p=101503#post101503), it seems that I can use all the IO that I can get, which would tip me in favour of the UC300eth.

Also, you mentioned being locked into Mach 3/4, as a negative. What other (better?) alternatives are there, and why is that?



I've not read all your thread but i saw you where struggling regards ballscrews and sizing them. So here's a suggestion which might help that I've built many machines using.
Use 2020 with 2:1 ratio. This gives same speed as 10mm pitch but halfs the screw speed so less chance of whipping screws. It also doubles the torque from motors.
Also very easy to increase velocity if needed by changing ratio.

I guess I just ignored the existence of 2020 Ballscrews :D I calculated it through in the motor spreadsheet, and, asuming I did all the correct modifications in terms of doubled motor RPM and doubled torque, I could actually now hit 12m/s rapids with the same motor, compared to 7.5m/s before. Thank you for the recommendation!



Next suggestion is to buy drives that accept AC then you only need to buy transformer. That said building toroidal DC psu isn't difficult and don't let anyone tell you different but they are the best type for Cnc machine that moves quickly with high speed directional changes like routers make where drives have to handle dynamo affect of steppers.

Building a PSU should be fine, for the most part, but just so I can make myself a complete picture, do you have any recommendations of AC Drivers that are worth it? I am kind of missing an equivalent to what mouser or arrow are in the electronics component space, where you have one page that you can search for all components you could ever need, all in one place. I never know where to look for the parts involved.

On a different note, I have seen Jog and MPG pendants mentioned and presented on shop pages. What do those things do exactly? What I have found repeatedly on the topic, is that they are used for manual operation of the machine, however I was under the impression that this would also be possible directly from the control software. Am I mistaken here, or is there a big advantage to using such pendants?

[JAZZCNC]

Understood. I've been scouring the forum and the web, but it seems my search-fu is a bit off, since I could not really find a conclusive answer on the differences of the UC300eth, UC400eth and AXBB-E, especially since CNCDrive's web pages are kind of scarce on the matter. As far as I am able to see, the 300 just has more IO than the 400, withe the AXBB-E has the same amount of IO as the 400, but a built in Breakout in a nicer package? Judging from this post (http://www.mycncuk.com/threads/11808-Any-USB-Ethernet-controller-suggestions?p=101503#post101503), it seems that I can use all the IO that I can get, which would tip me in favour of the UC300eth.

Also, you mentioned being locked into Mach 3/4, as a negative. What other (better?) alternatives are there, and why is that?

Yes your spot on with differences between these boards. The UC300 is the better option if you need lots of I/O. Coupled with a Good Bob that can accept 24v signals it's an excellent setup.

The alternative to Mach3/4 is UCCNC. Whether it's better or not is matter of opinion. The trajectory planner or put in simpler terms the way it creates motion is better and smoother than Mach3, can't speak for Mach4 because it's so full of bugs don't trust it and won't use it.
Now mach3 as it's advantages in that it's got massive following and is much easier to write custom scripts etc and customise to your exact needs.
What can say is both work well and will do what 99% of people want straight out the box.






I guess I just ignored the existence of 2020 Ballscrews :D I calculated it through in the motor spreadsheet, and, asuming I did all the correct modifications in terms of doubled motor RPM and doubled torque, I could actually now hit 12m/s rapids with the same motor, compared to 7.5m/s before. Thank you for the recommendation!

If by12m/s your meaning 12 meters per second then your massively off with your settings. 12 Meters per Min is more realistic figure.

To be honest that spread sheet is load of rubbish and spits out unrealistic figures. Real world is much different due to the many variables that affect machine performance.




IBuilding a PSU should be fine, for the most part, but just so I can make myself a complete picture, do you have any recommendations of AC Drivers that are worth it?

If you can find any the AM882-H are AC version. They are hard to find now thou.
If your on a budget these are not bad drives which i've fitted on several machines without any troubles and good performance.
https://www.ebay.co.uk/itm/2DM860H-2phase-NEMA23-NEMA34-Stepper-Motor-Driver-32bit-DSP-DC80V-1-5-6-0A/401403682399?_trkparms=ao%3D1%26asc%3D201407281139 35%26meid%3D7d59d4f8470543ffba10d7896d432710%26pid %3D100148%26itm%3D401403682399%26pmt%3D1%26noa%3D1 %26pg%3D2059210&_trksid=p2059210.c100148.m2813

I mostly tend to fit Closed loop hybrid steppers these days and many of them can be driven with AC or DC.



On a different note, I have seen Jog and MPG pendants mentioned and presented on shop pages. What do those things do exactly? What I have found repeatedly on the topic, is that they are used for manual operation of the machine, however I was under the impression that this would also be possible directly from the control software. Am I mistaken here, or is there a big advantage to using such pendants?

MPG / pendant is just a hand held box that lets you stand at the machine and Jog it arround rather than using the PC keyboard. On large machine this is very helpfull when setting tools or find edges of material etc as walking back to PC to make move is a pain.

[Chrono]

If by12m/s your meaning 12 meters per second then your massively off with your settings. 12 Meters per Min is more realistic figure.

To be honest that spread sheet is load of rubbish and spits out unrealistic figures. Real world is much different due to the many variables that affect machine performance.


Ah yes, indeed it is 12m/min, don't know how I have read that wrong every single time... :hopelessness:

I have been using the spreadsheet to dimension all my motors so far. Is there a better way to do this, or will it all just come together in the final build? I am guessing there is no real way to account for all the variables the steppers will be influenced by when it comes to it, but I guess what I am asking is: Is it still a good idea to run the motors you can find through the spreadsheet to find the "best one" you can still drive?

[JAZZCNC]

Ah yes, indeed it is 12m/min, don't know how I have read that wrong every single time... :hopelessness:

I have been using the spreadsheet to dimension all my motors so far. Is there a better way to do this, or will it all just come together in the final build? I am guessing there is no real way to account for all the variables the steppers will be influenced by when it comes to it, but I guess what I am asking is: Is it still a good idea to run the motors you can find through the spreadsheet to find the "best one" you can still drive?

Lots of things come into play, not all motors are equal for instance and same size motor can have ridicuously high inductance compared to another and the spread sheet doesn't and cannot really account for these variables.
Combine this with all the other variables and it's very much trial and error in some ways.

For instance I've helped folks troubleshoot machines with motors that would lift empire state building yet they stall and run slow because they wrongly sized components like ballscrews, gearboxs ratios etc or they did such poor job of building and allignment the machine is crippled.

The best advice I can give is to look around for similar size machine built with similar materials/components and copy what works.

Thru experience I can tell you that Single 4Nm nema23 with inductance around 2-3Mh wired in parallel running 4 to 4.5A with 68Vdc on 80Vdc Digital drives connected to 16mm Dia10mm pitch ballscrew with a Good motion controller (not parallel port) will easily and reliably reach 12M/min moving 40-50Kg.

For longer than 1200mm 20mm 10mm pitch screws you'll need to use nema 34 or use method like I suggested using larger pitch with ratio.
Same for dual screws you'll need 2 x Nema 23 upto 20mm Dia, Single 4nm Nema 23 won't drive 2 screws, even with ratio.

If you go to nema 34 then for better speeds you'll need more volts.

[MartinS]

Thru experience I can tell you that Single 4Nm nema23 with inductance around 2-3Mh wired in parallel running 4 to 4.5A with 68Vdc on 80Vdc Digital drives connected to 16mm Dia10mm pitch ballscrew with a Good motion controller (not parallel port) will easily and reliably reach 12M/min moving 40-50Kg

Hi Chrono,

Dean,

For those of us who are learning and planning, could you expand on the above?

Is this 60BYG401-03 https://cnc4you.co.uk/resources/Stepper%20Motor%20Nema%2023%2060BYGH401-03%204Nm.pdf an example of the stepper categorised above? or if you have another preferred source/model, what is it?

and


I mostly tend to fit Closed loop hybrid steppers these days and many of them can be driven with AC or DC.

Are those different from the above and do they need different drivers?

Thanks,
Martin

[JAZZCNC]

Dean,

For those of us who are learning and planning, could you expand on the above?

Is this 60BYG401-03 https://cnc4you.co.uk/resources/Stepper%20Motor%20Nema%2023%2060BYGH401-03%204Nm.pdf an example of the stepper categorised above? or if you have another preferred source/model, what is it?

Yes those are good motors which I've used many times. The sheet say's it all really When wired in parallel the Inductance is 3.0mh which is a good value. The lower the inductance the better.



Are those different from the above and do they need different drivers?

Yes and No.
Yes they are still a stepper motor but they have encoders built into them.
No because while they are stepper motors the drives they use are more like Servo drives and designed to read the encoder to track the motors rotation.
Normal stepper drive just recieves pulses and tells the motors to rotate but doesn't actually check or know if actually rotated the commanded distance. So for instance if your axis is binding stiff or very heavy you could lose steps and neither the drives or control software(mach3) know anything about it which leads to inaccurate cuts.

Closed loop drives work differently in that they use the Encoder on the motor to check if it rotated the commanded distance. If it over shot or under shot they correct it's position so returns to commanded position. If they over shoot more than programmed distance they will throw a fault message that can be sent to the control software so can stop the cutting.

While they are Not Full Closed loop, meaning they don't feed the motor position back to controller which still takes it on blind faith that commanded position as been reached. They are a good alternative because they do correct for small positional errors inside the drives and warn the controller if large positional errors occur. Compared Standard stepper drives which have no clue where the motor ended up so can not tell the control software if errors occur. The first you know about it is when the job is finished and wrong or worse machine crashes because it's got lost.!!

So in short yes they are different and need special drives, No they are still stepper motors.
Often you buy the closed loop drives and motors together as a set. Like these.
https://www.ebay.co.uk/itm/CNC-Hybrid-NEMA34-Closed-Loop-Stepper-Motor-Drive-4N-M-HBS86-Servo-Driver-3K-RPM/163753212522?epid=25030566643&hash=item262073ba6a:g:ZjIAAOSwjlVcIJIb

https://www.ebay.co.uk/itm/NEW-Leadshine-8Nm-Nema34-Closed-Loop-Stepper-Motor-Drive-12N-M-HBSS86-HBS1108S/332834511548?hash=item4d7e7b9abc:g:r~UAAOSwqFBbvGx S

Hope that helps.

[MartinS]

Yes, thanks, most helpful.


So in short yes they are different and need special drives, No they are still stepper motors.
Often you buy the closed loop drives and motors together as a set. Like these.
https://www.ebay.co.uk/itm/CNC-Hybri...IAAOSwjlVcIJIb

https://www.ebay.co.uk/itm/NEW-Leads...UAAOSwqFBbvGxS

I guess that we still need a low inductance. I can't see it specified in the links.

[JAZZCNC]

I guess that we still need a low inductance. I can't see it specified in the links.

Yes the same applies but I've yet to find a Closed-loop drive/motor combination that uses high inductance motors and just about every set I've used gives reasonable torque at higher speeds, most reach 1500rpm before torques drops away.

Also, there are closed-loop systems that use 3 phase motors which give much better torque and smooth operation. To be honest I mostly fit 3 phase systems on larger machines.

The only thing you have to watch for with smaller closed-loop systems is that they use low voltage, often 50Vdc drives and they do not tolerate more than 50V and will be damaged if rises above. This means you need to run safe margin, 44 - 45V is recommended. That said they still tend perform very well and better than a standard stepper at same voltage. Think this must be to do with the way the closed loop drives work.!

The bottom line that I've found is that closed-loop systems tend to be slightly stronger at higher feeds and the closed-loop drive ensure the position is maintained.

That said a correctly sized and set up Open-loop stepper system is just as accurate and shouldn't lose position if tuned correctly. Thou Closed-loop systems are coming down in price and the difference in price is now such that closed loop is the wiser choice.

[Chrono]

So, if i got that correctly, I want a stepper that has a low inductance rating and a high current rating, correct?

I plan to use a single NEMA 34 for both X-axis screws(2x 1800mm 2020 screws, around 75kg of mass on the gantry) and a single NEMA 34 for the Y axis as well (1300mm, single 1620 screw, around 25kg of mass to move), with a NEMA 23 for the Z-Axis(single 500mm 1610 screw, 15kg). Taking another look with those qualities in mind, I come up with the following choices:


X-Axis: ST8918M6708-A (https://de.nanotec.com/fileadmin/files/Datenblaetter/Schrittmotoren/ST8918/ST8918M6708-A.pdf)
Y-Axis: ACT 34SSM8460EC
(https://cdn-reichelt.de/documents/datenblatt/X200/34SSM8460-EC1000.pdf)
Z-Axis: 60BYG401-03
(https://cnc4you.co.uk/resources/Stepper%20Motor%20Nema%2023%2060BYGH401-03%204Nm.pdf)


Would these be good choices for my system?

[Chrono]

Well... I have been inactive for a while now, I guess... But a certain event that might entail additional customs charges for the parts that I want to source from Britain, is pressuring me back into activity :D

Now I did not do nothing all this time, but I did get a plan going for the power lines. As mentioned before, I have someone with more experience than me in the field help me with the selection of specific parts, so the plan is just for the power connections, not the data lines. These are to be specified when the parts are fixed (Also, logic level stuff is more my expertise, so I can more easily deal with all of that on my own, while I am more concerned about getting all the higher-voltage lines done to spec).

26665

I also already got a hold of a couple parts: The person helping me has access to some old parts that are not used anymore, so I already have a 24V PSU, all the connector blocks and wiring that I could ever need, as well as a transformer and the fuses.

What I am looking to get in a more time sensitive manner, is the UC300eth controller, as well as the steppers mentioned in the above post and the AM882 drivers to run them. The drivers and controller have already been discussed in this thread, but it is the motors I am still a bit unsure about. They were chosen under the constraints that were brought up, but I might have overlooked something.

On a different note of mechanics: I am pretty much ready, at this point to start buying parts, like the alu, the plates and the rails. I actually already have one of the rails here. And since there does not seem to be anything to change in the design, I will probably proceed with that, as soon as the electrical part is signed off on by the council of more knowledged people here :) And I guess, once I start buying, it is finally time to open a build log thread.

[AndyUK]

Well... I have been inactive for a while now, I guess... But a certain event that might entail additional customs charges for the parts that I want to source from Britain, is pressuring me back into activity :D

You've got till the end of Jan - I'll give you good odds on that :)


Now I did not do nothing all this time, but I did get a plan going for the power lines. As mentioned before, I have someone with more experience than me in the field help me with the selection of specific parts, so the plan is just for the power connections, not the data lines. These are to be specified when the parts are fixed (Also, logic level stuff is more my expertise, so I can more easily deal with all of that on my own, while I am more concerned about getting all the higher-voltage lines done to spec).

Looks good - Although read the VFD manual about switching it on and off with a relay - mine specifically says not to. I'm hoping UCCNC will drop the spindle enable when it receives an E-Stop command, but have yet to test this.

I'm also planning to use FA/FB/FC for a fault signal feedback from the VFD to the UC300eth - I figure I'd rather use this function for stopping the CNC when the spindle faults (and therefore stops rotating) than running the water pump - which can just be run continuously anyway. I don't like the idea of the spindle stopping and then the CNC trying to force the bit through stock.... that sounds like a bad situation.



I also already got a hold of a couple parts: The person helping me has access to some old parts that are not used anymore, so I already have a 24V PSU, all the connector blocks and wiring that I could ever need, as well as a transformer and the fuses.

Cool. Also look for an electronics cab which will help you start placing components etc. I used Tempa Pano - rather cheap, but not perfect quality.



What I am looking to get in a more time sensitive manner, is the UC300eth controller, as well as the steppers mentioned in the above post and the AM882 drivers to run them. The drivers and controller have already been discussed in this thread, but it is the motors I am still a bit unsure about. They were chosen under the constraints that were brought up, but I might have overlooked something.

Don't forget to look into breakout boards. I really like my UB1. May as well buy them at the same time. Why is the UC300 time-sensitive? Usually its best to get the mechanicals in order and built before starting to buy the big ticket electrical components - you never know whats just round the corner in terms of new models, and you'll end up ticking away your warranty while you're still building.


On a different note of mechanics: I am pretty much ready, at this point to start buying parts, like the alu, the plates and the rails. I actually already have one of the rails here. And since there does not seem to be anything to change in the design, I will probably proceed with that, as soon as the electrical part is signed off on by the council of more knowledged people here :) And I guess, once I start buying, it is finally time to open a build log thread.

Looking forward to it! :)

[Chrono]

You've got till the end of Jan - I'll give you good odds on that :)

Looks good - Although read the VFD manual about switching it on and off with a relay - mine specifically says not to. I'm hoping UCCNC will drop the spindle enable when it receives an E-Stop command, but have yet to test this.

I'm also planning to use FA/FB/FC for a fault signal feedback from the VFD to the UC300eth - I figure I'd rather use this function for stopping the CNC when the spindle faults (and therefore stops rotating) than running the water pump - which can just be run continuously anyway. I don't like the idea of the spindle stopping and then the CNC trying to force the bit through stock.... that sounds like a bad situation.


Guess I really need to take a better look... With the F-Terminals, and with the whole schematic to be honest, I took a look at JoeHarris' build and for the most part copied it over, and slightly changed it to fit my setup. Thanks for making me aware that that might not be the best option. Time to dig out the datasheet.





Cool. Also look for an electronics cab which will help you start placing components etc. I used Tempa Pano - rather cheap, but not perfect quality.


Yep, already got that covered. Most likely my helper will be able to source one for cheap, that is excess or old stock.




Don't forget to look into breakout boards. I really like my UB1. May as well buy them at the same time. Why is the UC300 time-sensitive? Usually its best to get the mechanicals in order and built before starting to buy the big ticket electrical components - you never know whats just round the corner in terms of new models, and you'll end up ticking away your warranty while you're still building.

Looking forward to it! :)

The urgency was more from the time of writing, since I did not know, at the time, that I would have till January, and these are the parts I need to get from the UK, since they are massively more expensive here.

I actually wanted to ask about BOBs, but completely forgot. As far as I understand, they step up the controllers signals to 24V and handle isolation between the electronics and the controller? The UB1 looks great, but the price is another 200€ on top (on that note: Where did you buy your BOB, if I may ask? I can only find a couple shops, some of which sell it for twice as much as others)... if only i had a schematic, then i could just roll my own :D

But you are right, it makes more sense to get the mechanical side figured out first... And since that setup is ready to go, I guess it is time to clean up the workshop and get the space cleaned out that I want to put the router in. Then order the alu, sheet metal and the linear motion equipment and put that together, before moving on. One step at a time.

Regarding the linear motion: With both the 25mm rails and the ballscrews, I have the choice between HIWIN stuff and "mainland china" rails with "C7" ballscrews. The difference is 670$ to more than 1000$... Are there any verdicts on the quality of the chinese alternatives?

[JAZZCNC]

As far as I understand, they step up the controllers signals to 24V and handle isolation between the electronics and the controller? The UB1 looks great, but the price is another 200€ on top (on that note: Where did you buy your BOB, if I may ask? I can only find a couple shops, some of which sell it for twice as much as others)... if only i had a schematic, then i could just roll my own :D

Don't skimp on the BOB it's just as important as the controller and the single most troublesome part of any machine when it's done on the cheap.
The UB1 is good BOB, thou i'm not keen on the spring loaded terminals but other than that it's well made and very capable.
I've seen Many electronics geeks try to Roll there own and 99% fail resulting in wasted time only to buy one in end.



Regarding the linear motion: With both the 25mm rails and the ballscrews, I have the choice between HIWIN stuff and "mainland china" rails with "C7" ballscrews. The difference is 670$ to more than 1000$... Are there any verdicts on the quality of the chinese alternatives?

You can get Hi-win from china and the ballscrews are Ok for the money. They also sell C5 if you want little better.

You don't need 25mm rails for machine this size and it will actually negatively affect the machine compared to 20mm rails because of the extra inertia etc the motors will have to deal with. These may seem little negative things but together they add up into large negative which affects performance.

Regards the VFD it will damage the VFD eventually by switching it off and on thru a relay. It's also not safe due to capacitors causing a delay in it powering down.

Not looked at the schematic too close but will take a look. The schematic Joe used mostly came from me so should make sense..

[Chrono]

Don't skimp on the BOB it's just as important as the controller and the single most troublesome part of any machine when it's done on the cheap.
The UB1 is good BOB, thou i'm not keen on the spring loaded terminals but other than that it's well made and very capable.
I've seen Many electronics geeks try to Roll there own and 99% fail resulting in wasted time only to buy one in end.


Got it. Makes sense to me... There are just too many variables for me to try and get it on the first try, and on the second I would likely be overshooting the cost of the UB1 anyways.




You can get Hi-win from china and the ballscrews are Ok for the money. They also sell C5 if you want little better.

You don't need 25mm rails for machine this size and it will actually negatively affect the machine compared to 20mm rails because of the extra inertia etc the motors will have to deal with. These may seem little negative things but together they add up into large negative which affects performance.


I have checked again, and as it turns out, my memory was wrong... I was already planning on using 20mm rails, and that is what is in the CAD model. I am planning to get them from china, but HIWIN vs china rails are still 300$... Would that be worth it, or are the chinese ones good as well?



Regards the VFD it will damage the VFD eventually by switching it off and on thru a relay. It's also not safe due to capacitors causing a delay in it powering down.

Not looked at the schematic too close but will take a look. The schematic Joe used mostly came from me so should make sense..

Got it. So the only E-Stop for the VFD then is the mains switch and the internal E-Stop signal, I am guessing?

[AndyUK]

Where did you buy your BOB, if I may ask?

I got my UC300eth and UB1 as a pair from CNCROOM.com in Thailand. They are the designers of the UB1, so are very helpful when you have questions. As you say, not the cheapest (and they label correctly so you will be stung for the full correct amount import duty) but the quality of the product is high, and the delivery was very fast considering the distance (less than a week).

I also purchased my UCCNC licence from them rather than direct from CNCDrive (because no VAT) - but do it separately so its not on your invoice for the UC300 and UB1. You'll need the serial number of your UC300 so wait for that to arrive first.

[ericks]

Maybe something you can look at. I used a UC300ETH for my own machine with an Aussie made bob. For the control panels i plan to put on the market i just purchased the AXBB-E motion controller that already has a bob built in. Have not tested it but i expect it to be good:)