Automatic squaring will drive each motor into its owm endstop. Each motor needs its own driver for each end to be driven independently. When you home Z, it will push each motor towards the endstops. When the first motor hits the endstop, the second will continue until it reaches its endstop. After that, they will always move in lockstep.
With the mini rambo, you have 4 drivers. It’s meant to be used with a 3D printer, so there is an x,y,z, and extruder driver (E0). You can repurpose the E0 as Z2. That will let you then assign an endstop to the Z2 motor.
There is no way to convert the software on the mini rambo back into something you can use. But if you start with the mpcnc mini rambo firmware from Ryan, you can add dual endstop to Z on it.
- disable the E0 driver. Set the number of extruders to 0.
- Enable dual Z motors. In configuration_adv.h find the dual motor z and enable it.
- Enable dual Z endtops. In configuration_adv.h, right there next to dual motor z enable dual endstop z.
- Flash the board according to Ryan’s instructions.
- Wire the Z2 motor to the E0 port. Wire the Z1 endstop to zmin. Wire the Z2 endstop to zmax. Endstops get wired between (s) and (-). Not to (+).
- Check the endstops with “M119” before trying homing, which is “G28 Z”. You might need to go back and change the Z endstop inverting or Z2 endstop inverting in Configuration.h.
That will let you install endstops at the bottom of Z. If you want to home to the top instead, you need to also do this:
7) In Configuration.h, change the Z home dir to +.
8) In Configuration_adv.h, change the Z2 endstop pin to ymax.
9) Wire the Z1 enstop to zmax. Wire the z2 endstop to ymax.
If you ever decide to quit on this process, just flash Ryan’s firmware with no edits. That is basically what is on there now, although it might be a slightly different version. As long as you stay with Ryan’s firmware, there is a small risk that you will change the firmware on the board, without getting it right. If you make a mistake while flashing, it will not have installed anything.
Flashing the board is a worthy skill to have. There are many other options available to you when you can flash a mini rambo.