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CNC Electronics - Grounding and probe Answered


Reading about proper grounding of cnc electronics I saw that ground has to be isolated from power supplies negative. So, I have a copper plate with ground cables from 48v, 12v and 5v power supplies with ground cable from the wall. Everything works fine but the machine itself, has no ground cable because if I attach the negative of my probe cable I will be connecting negative to ground...

This morning touching the machine structure and the door handle (the door is metalic) I felt a light discharge. Should I connect the maching to ground? Can this affect in any way the electronics with that negative to ground? ( the discharge was lightly, I can live with that lol)

The router has no ground cable, maybe that was the reason for the discharge.




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1 year ago

Grounding such equippment is sometimes tricky.
The electronics driving the motors produce a lot of interference.
In an indstrial setup all housing and external parts are grounded to earth.
All electronics that benefit from grounding will share the same negavite.
And all power supplies, probes or similar would be grounded to earth using filters.

Let's try a worst case example, an inverter driven plasma cutter or welder:
Here the entire housing of the machine is grounded to earth.
However, the work platform is isolated from this erth grounding if the inverter requires to be without earth grounding.
Instead you get two seperate "grounds".
One for all machine parts not connected to the inverter and one "floating" ground for all inverter related things.
If the grounding would be shared then the interference from the inverter would simply destroy the electronics.
Downside of such setups is that static electricity can build up.
Hence often filters are used that do block all high frequency interference but let DC pass through.

If your probe won't work with a shared ground connection then I guess the only way out would be to isolate it.
Either through the workpiece or by means of seperating the grounding for the probe circuit.
But it would be best to consult the manufacturer to excatly know what is possible and/or required.