Short earth with 24Vss(gnd) to have signal on endmill can be harmful?

[sn4k3]

I have an all steel CNC router that chassi is connected to mains Earth, so all body is earthed, without earthing and only when spindle is rotating chassis have about 240VAC but very low current as it won't shock me nor turn on little bulb, it may due large coil on spindle or poor vdf that generate EMI. With body earthed that voltage gone and turn 0V, so far so good, nothing wrong.

My question is: Can I short mains Earth with DC 24Vss(GND)? I ask that because that way i will have the GND on endmill which is useful for probing/touch plates/edge finders and avoid 1 more long cable.

Can this be a bad pratice, have gnd shorted with earth all the time?

Also the 24V PSU is isolated from 5V PSU which powers the control board. The 24V PSU feeds some induction sensors and a receptor, so it's only for inputs.

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