I assembled my Shapeoko Pro and discovered that I had a defective Z axis limit switch (one wire never crimped). A phone call to Support had a new switch on the way to me. It arrived today.
While I was waiting for the new switch I figured out how to hotwire the old one to work and the machine homed and jogged beautifully. When I swapped out the old switch for the new one however, I have a new issue. Even though the limit switch tests good, when I try to initialize the machine the Z axis moves toward Z negative instead of positive toward the limit switch. I then get an error and homing was incomplete.
Why would it work with the old switch but not the new one? If I unplug the limit switch and try to initialize the machine then the axis moves in the proper direction. Totally whacky.
The controller is seeing the switch as activated. You’re seeing the machine try to pull off of the switch.
Might be a miswired switch.
When you plug in the Z switch, does the Z indicator LED turn on?
No, as I said the switch tests good. Before attempting to initialize it, you can simply place a spindle wrench near the switch to test it. In my case the light is off until the wrench passes close to it, then the light illuminates.
What about on the main control board? That is a better indicator that the switch signal is correct.
Can you get a screenshot of the homing failed error?
Recap: My original Z limit switch was defective (one wire was never crimped). Carbide 3D sent a replacement right away. The replacement switch was also defective. It apparently had a short somewhere. It was triggering a limit at the controller even when the LED on the sensor/switch was not illuminated. The fix was to splice my old switch onto the new wire/connector. All works as it should now.