I have a CNC milling/engraving machine that I built, and just added limit (home) switches. The CNC commander has been working fine, but now homing seems to be an issue. All of the switches function correctly and I see them in the status section of the main window. X & Y work perfectly, but Z is acting strangely. It heads towards the limit switch (I have the directions all set correctly), but does it in two very short attempts and does not get there. It only moves a couple of mm at a time. After that the X & Y axes move as they should (simultaneously, although I have the order set to Z , X , Y). If I repeat the homing sequence, and it reaches the z-axis switch, it alarms out and stops. Any ideas on why this would be happening?
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If you are using the Protoneer shield for the Uno, the V3.0 shield does not have any form of filtering on the limit switch inputs, but the V3.50 board does. I added external R-C filters on my V3.00 before upgrading it to a V3.50 (beware the changed pinouts!)
UPDATE - Just for the heck of it I put a 150nF capacitor across the switch (input pin to ground), and the homing operation of the z-axis completely changed. The direction changed and it found the limit switch. Must have been picking up stepper noise. I hope this was really the fix.
What is your maximum travel limits in peripherals tab? What controller are you using? Are they inductive or mechanical limit switches? When it alarms, click on the alarn to reveal a translation of the alarm. What alarm is it?