Sensors and Gantry Grounding

Issue #

A small instance of machines, like the Ender 3, can exhibit issues with the EZABL sensors staying triggered due to poor/no grounding. We do have an option to turn the motors off (XYE) during probing in our latest firmware which fixes this issue but the root cause is that the electrical interference has nowhere to go on the X gantry due to it being isolated. The stepper driver signals can leak into the X gantry frame and then cause issues where the sensors can be constantly triggered.

Possible Fixes #

PSU Grounding #

Check your PSU grounding before attempting any of the below fixes. See here for how to do this: Printer Grounding – How to Check your PSU and Grounding Your Bed

Firmware Tweaks #

Turn on the “PROBING_MOTORS_OFF” option in our Unified 2 Firmware. This was added in starting with version 2.0 and higher. This will turn the motors on XYE off during probing automatically just like the firmware does already with the bed and hotend heaters.

Ground the Gantry #

Run a ground wire from the X motor to the printer frame or another motor on the frame. This will allow the electrical interference to drain from the X gantry and not interfere with the probe. Some machines have non-recessed screw holes on the rear of the motor and you can ground off of there if your machine doesn’t have the non-recessed holes you can put the ground wire from the motor screw that holds it to the bracket instead. If you have stepper dampers then put the ground wire on the other side screw that holds the damper to the Z gantry. You want the gantry grounded, the motor doesn’t matter.

NOTE: If you have stepper dampers then you want to connect the ground wire to the frame of the printer, not the motor. This is because the stepper damper will act as an insulator which will not make the ground wire drain the EMI from the gantry/frame.

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