Spindle grounding- manufacturer says to not ground

[reg.miller]

If you want to call someone pathetic, it's best to learn how to spell if first , mr. perthitic. :wedge:

a small voltage will not cause erosion of the Bearings

Wrong. A small voltage can lead to a high current across a near zero resistance. This DOES cause problems on some machines, if you are unaware of that , it's probably because you are perthitic..

I was replying to OP who says he was informed of a possible problem.

A piece of paper that came in the package says specifically NOT to ground the spindle, otherwise damage will occur when cutting metals.

This was nothing to do with "breakout boards" which actually means nothing in technical terms so I have no idea what you think gets blow out. I would not use a probe circuit without an opto isolator for exactly this reason. If hobbyists are connecting straight to an Arduino of something, they will have problems.

Since you clearly have nothing to add to the discussion, I don't know why you bother replying except to be smart. Not that helpful.

[Al_The_Man]

So why post you are perthitic.

Any Ac 3 phase motor driven with a VFD Drive produces Rotor Voltage, a small voltage will not cause erosion of the Bearings

Perthitic ? New one on me! , is it as bad as Covid?
An AC induction motor does not produce any real voltage in the rotor shorted turns it is extremely small, there is a very high current flow however in the the single turns of a squirrel cage rotor which produce fractions of a volt.
,

[mactec54]

If you want to call someone pathetic, it's best to learn how to spell if first

Pathetic, spelling is correct

ADJECTIVE
arousing pity, especially through vulnerability or sadness.
"she looked so pathetic that I bent down to comfort her" · [more]
synonyms:
pitiful · pitiable · piteous · to be pitied · moving · touching · poignant · [more]
miserably inadequate; of very low standard.
"he's a pathetic excuse for a man" · [more]
synonyms:
feeble · woeful · sorry · poor · pitiful · lamentable · deplorable · [more]
archaic
relating to the emotions.

This was related to your political statement, nothing more, pathetic was the correct word

[mactec54]

Perthitic ? New one on me! , is it as bad as Covid?
An AC induction motor does not produce any real voltage in the rotor shorted turns it is extremely small, there is a very high current flow however in the the single turns of a squirrel cage rotor which produce fractions of a volt.
,

Really, you sure of this.

You should know better than this, so you are saying the motor manufactures don't know what they are talking about. hint what happened to CMV.

[Al_The_Man]

You should know better than this, .

I am probably perthitic ?

[mactec54]

I am probably perthitic ?

The least you could do is to spell it correct, as I was corrected, anyone can make a spelling mistake, who cares it got the message across.