[numpad0]

I long had dimensional accuracy issue that the whole axes seemed to stretch and contract like 5%, on a cartesian 3D printer, and it just went away after I switched to Servo42B setup.

I think it’s microstepping. Steppers with microstepping enabled and controlled by an 8-but micro must be assumed to produce zero holding torque and assumed they always miss a step or two.

[craftinator]

Upgrade the controller. For a hobbyist machine, the ESP32 CNC controller sold on Tindie is well suited to deal with that, and costs ~$35.

[StavrosK]

I made a PCB for an ESP32 CNC controller, if anyone finds it useful:

https://gitlab.com/stavros/esp32-cnc

[craftinator]

Nice! I'll check it out! Here's a link to the one I'm using:

https://www.tindie.com/products/33366583/grbl_esp32-cnc-deve...

The developer is really responsive, might be worth collaborating since you have put in similar work.

[taneq]

I'm running one of these on my Lowrider 2 and it's pretty great. The only real issue I've had was with limit switches (I got cocky and didn't use shielded cables, then ran the sensor cables with the stepper ones, so I had to add pull-ups and filtering caps to smooth out the noise... lesson learned!) The web interface does seem to crash semi-regularly if you step off the straight and narrow but once you know the pitfalls it's great to be able to drive your router around with a laptop or phone, and to be able to upload files over wifi.

[dekhn]

There are several newer boards from Bart (including the 6-pack which has some add on modules).

Grbl ESP32 is great. Easily the best of the firmwares I've used so far.

[craftinator]

I've been interested in upgrading to his newer boards, but I'm not sure I want the added complexity at the moment. Have you used the generic modular one? If so, how does it compare to the older one I linked to?

[dekhn]

Interesting question; I just had to go through this myself. I really only wanted 3 axes and considered the older one you linked to (which isn't marked 'retired', but is "out of stock"). The first thing I'd mention is that the older board doesn't support the new style of drivers (old = TI DRV8825, new = Trinamic SPI). SPI drivers are much nicer for a number of reasons, in particular you can change the motor current via software, and with the trinamics there's support for stallguard.

In my case I'm not building a CNC, but controlling the axes of a microscope (X, Y, Z) plus the intensity of the illuminator and likely several other things, so the 6-pack (which I also use on my CNC) had what I wanted.

Oh, you can also use either onboard or external motor drivers with the 6-pack- external motor drivers are good for NEMA23 and other large motors.

[jbay808]

Microstepping does not reduce torque in any respect.