First 3-axis Build: A4

[Storken]

I have searched through many posts, and ordered some parts - but somewhere inbetween my studies, my cnc plans was laid to rest. I'm going to finish it now and I plan on making this my build log. Having a place to store links and ideas is needed, and this log will function as that.

Build name: A4

What I would like to achieve: Fine precision, A4 working area, 7 cm Z-axis, pcb double sided milling, jewelery wax milling - that's about it.

So far I've collected 4 8Amp drivers, totally overkill - but they can be current controlled down to 0,5A. Three huge stepper motors (8 wire) I'll use two, one for each side, for the y-axis (longest). I'll use one for the x-axis and I need one more for the z-axis.

Cupboard slides, I've got a ****load of them. I plan on using these in the z-axis. I'll add solidworks drawings later. Rack and pinion gears in steel will be bought from McMaster-Carr. I'm thinking of letting the whole "arch" (y axis)rest on 4 rather large standard gears. Cupboard slides will be used for x-axis.

Firstly I'll use a normal dremel tool, but I plan on upgrading this to a better one after a while.

I'm thinking about using the usb solution planet-cnc offers. But this is still to be planned better.

Thats it for now. I hope to come back with solidworks drawings and pictures after building is commenced

[jckstrthmghty]

for such a small cutting area why are you using r&p and not leadscrew?

If you are looking for percision I think your rails would have to be a priority. Drawer slides will have a lot of play. Mind you it all depends on how you define fine percision.

[Storken]

for such a small cutting area why are you using r&p and not leadscrew?

If you are looking for percision I think your rails would have to be a priority. Drawer slides will have a lot of play. Mind you it all depends on how you define fine percision.

My initial idea was to use r&p since I wouldn need linear rails for the y-axis. I should probably rethink this or what?

My drawer slides are of the really heavy sort. The ones I have are heavy duty.

Should I go with three lead screws (all axes), linear rails on x and y axis and beefy drawer slides on z axis?

Aliexpress seems to have cheap lead/ballscrews and linear rails - what size should I look for?

I should define fine precision, yes. But I'm not sure myself how small this should be. Trace width and spacing are 0,25mm on the smallest. Being able to produce this must be a goal.

[jckstrthmghty]

Sorry is that 0.25mm accuracy you are looking for?

Acme leadscrew is probably the best route for you. Percision 3/8" acme or even 1/2" will work well. You can use single start since efficiency and speed won't be a issue. There are plenty of US suppliers at reasonable costs. You wouldn't need much either for gthe table size. Not saying you can't use r&p but I think that system is better suited for large builds when leadscrew whip comes into play.

I don't know what to say about the rails. Regardless of durability drawer slides have play in them. For cutting wood maybe. Fine cuts? I don't know. I'm more than happy if you prove me wrong.

Look over at what microcarve has done. I think he has an ideal setup for what you would want. Not quite a4 but great accuracy.

[Storken]

Sorry is that 0.25mm accuracy you are looking for?

Acme leadscrew is probably the best route for you. Percision 3/8" acme or even 1/2" will work well. You can use single start since efficiency and speed won't be a issue. There are plenty of US suppliers at reasonable costs. You wouldn't need much either for gthe table size. Not saying you can't use r&p but I think that system is better suited for large builds when leadscrew whip comes into play.

I don't know what to say about the rails. Regardless of durability drawer slides have play in them. For cutting wood maybe. Fine cuts? I don't know. I'm more than happy if you prove me wrong.

Look over at what microcarve has done. I think he has an ideal setup for what you would want. Not quite a4 but great accuracy.

Hmm, lets say 25% of 0,25mm and rounding it to the nearest nice number: 0,05mm (or 50um). So that is not wood accuracy no - quite more accurate.

My drivers are capable of 16 step microstepping - and my steppers are 240 steps pr rev i think. I'll have to twist my head to get the resolution here - will do that later.

Swapping inbetween metric and imperial is annoying :P

I value your input highly, I'm not here to prove someone wrong Drawer z axis will be evaluated twice. For the record: I've dropped the idea of using drawer slides for the rails (x and y) - thinking linear (round perhaps) there. It's just that I have quite a few beefy ones I think will do the z-axis job no problem.

I'll check out microcarve

[jckstrthmghty]

Alright, lets say you use 1/2" 10 single start acme lead screw with your steppers and driver you should get 0.00066mm of potential resolution I think. Someone please correct my calculations if I am wrong.

For that level accuracy I think hardened steel rod for all axis is the way to go.

disclaimer, I'm just a novice in the world of cnc so I'm very much learning everyday. Keep that in mind when taking my advice.