Hi,

Started collecting parts and looking into building an Arduino based PCB mill.
I opted to go for a DIY solution as that is what is half the fun imho.

The parts I've got:
3x Nema 17 stepper motors 42oz
1.8°step angle (200 steps/revolution). Each phase draws current 0.4A at 12V, allowing for a holding torque of 26Ncm(36.8oz.in).
1x Arduino UNO with grbl 0.9
3x easy driver stepper motor driver boards
1x 550 18V motor to drive the spindle axle via belt and pulleys.
The spindle axle is fixed using four ballbearings that will be held in place on the Z-plate by alu-clamps.

1x 400mm ballscrew with anti-backlash-nut, bearings etc...I got a kit off ebay.
4x 8mm x 400mm chromed hardened steel rods with mounts.
A bunch of rail bearings or what they are called, english is not my first language.

I've gotten as far as getting the Arduino, easy driver boards, and stepper motors working together.
I'm currently working on the limit switches.
It's more or less copied from a schematic I found on this forum using google image search.
I used 430R pullup resistors as that was what was closest at hand, and from my limited understanding, it won't make a huge difference.
My question about this is that the switches are not isolated from eachother, they have contact, via resistors though, that may not matter?

I've got a 12V 5A supply for the stepper motors, a 18V 4A supply for the spindle motor, I have supplies to spare, should I power the Arduino board from a supply other than USB?

I did notice the stepper motors getting warm, not hot, during a brief test of Z-movement without any real weight on the Z-plate. The Easy Driver boards though, they got hot. I use heatsinks on the IC and plan on putting a 120x120mm PC fan blowing over the boards.
I had not at that point adjusted the current trimpot on the easydriver boards, it was set about midway when I recieved them.

I've swapped the wiring to thicker since testing the electronic part.

I know the wood-halfbaked-look isn't going to win any beauty competitions. And it is temporary, unless of course it works great.

For the X-axis I haven't decided on ballscrew kit or leadscrew as I use on the Z-axis.

The ballscrew kit is on it's way and intended for the Y-axis, not having a moving gantry but rather a moving Y-plate.

I hope I make some sense, I'm not familiar with terms etc when it comes to these things.

My goal for the build is to be able to mill atleast TSSOP28 package components.

Do I need to do anything to the firmware on the Arduino to use the limit switches?
I definetly want to probe the PCB's to get a good a result as possible, how would that wiring look? And as above, do I need to do anything with the firmware?

Any and all hints, tips, advice and help is grately appreciated.

/Jonas