MPCNC Z-Max Limit Switch Mount

thingiverse

This mount makes it simple to attach a small limit switch (with 9.5mm on-center mounting hole spacing) directly to the bolt head of one of the Z-axis bearings of an MPCNC. It's essential to check if there is clearance to fit a micro-switch, depending on the size of the spindle you have mounted. Max-limit switches are highly useful for CNC homing, especially when using grbl as your MPCNC firmware. This mount fits perfectly over a 1/2" bolt head and has 4mm nut traps for the limit switch mounting. I found it more convenient to install the limit switch mounting screws from the inside (so the screw length is not a concern), so I didn't use the small nut traps. The stock MPCNC tool mount presses the limit switch as it moves upward. I discovered that a limit switch with a wheel was necessary due to the extra 2mm of length it provides. A regular lever micro-switch wasn't long enough to activate reliably. Rotate the bolt head so that the limit switch body is slightly angled up and the limit switch arm is roughly horizontal. This both maximizes your homed z-height (by a few mm) and puts the micro-switch arm more directly in the path of the tool mount. I applied a small amount of glue to the bolt head to hold this in place securely, but if I ever need to disassemble it, I can still easily remove it. Don't forget to add strain relief on the wires. I used these: https://www.thingiverse.com/thing:1800896 printed at 75% scale, with a bit of CA glue to hold them in place.