Spindle ground - isn't

I’m in the process of setting up my 1.5kW water cooled spindle. I’ve seen comments on here about it being common for them to not be grounded, so I figured I’d check. Ohmmeter from ground screw in VFD to spindle case - no conductivity. So next step open the power connector on top of spindle and sure enough - pin 4 has nothing connected to it. So now that I’ve determined my spindle isn’t grounded, how do I ground it? I can solder a wire to the pin, but where do I connect the other end?

So, pin 4 of the connector mounted in the spindle is not connected to the spindle casing internally?

Nope, pin 4 has nothing connected to it!

Pretty typical issue unfortunately. Some folks do it like so:


For some reason Chinese spindles do not ground the body. Not sure if it is just the electrical standards for Chinese products or just cheapness. Even in the US some appliances are not grounded but they usually have a 2 prong plug and are double insulated so they are not required to ground the case of the tool. The research I have done about EU standards are also a spotty depending on which plug type you have. Many EU plugs only have two prongs and no ground.

So I guess since the standards vary so much as the owner you have to make sure you ground the case yourself. Sad but true.

Either that, or learn from this forum that G-Penny spindles happen to be grounded, and spare yourself the trouble.