Luthier CNC

[bluesking]

Don't take risks with the safety earthing of your spindle.

I haven't taken any risks: the spindle is earthed. Thats the reason why I had to introduce a ground loop to make my z probe work how I wanted and still be safe - at the cost of some potential interference...

It's a basic catch 22 - and the reason why many valve amps have a ground lift switch. Always seems a bit dangerous to me to leave it in the hands of the guitarist to decide what is safe! But it's there when you use multiple amps and you know they are all on the same mains circuit yet the ground loop is causing noise to get in the system.