Touch plate ground wire

Thanks Jim for the leg work you have put into this, and to all the others who have responded. I bought the components thar Eric mentioned above and install the splitter and grounded to the same screw. I can activate the touch probe by touching any part of the frame… EXCEPT a bit in the spindle or the spindle nose. The spindle housing will activate, but not the part that is needed… It is a GMT pics attached.

Hi Brian,
What kind of resistance reading do you get with an ohm meter from the spindle body to the output shaft? Maybe that spindle has ceramic bearings top and bottom?

no continuity at all

I was afraid if that :frowning:

To @jjneeb 's point, they only put the ceramic bearings at the point of load so the top bearing would always be metal. Ceramics are great with high loads but they are terrible at building load in a system. So generally the metal bearing is used to press the load into the ceramic bearings.

I assume that the GMT has plastic separating the core of the motor from the housing. That is a shame.

It could also employ sleeve bushings made from sintered bronze impregnated with grease. Grease being an excellent insulator. My money is on this explanation. I can’t see plastic in a high heat spindle as a load bearing structure.

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heck I can’t believe there would be sleeve bearings in any spindle, but a quick search did not reveal any info on bearings for the gmt. I currently have 4 spindles, 2 GMT’s, one on each machines and 2 hiteco’s in boxes. I have a good VOM and no matter how hard I scratched or what range I got nothing on the gmt’s and just a flash on the hitecos as far as ohms.

Ok after changing the battery on my very good vom I get 1.8 - 2K on the hiteco nothing on gmt

continuity at all

Thats in line with what I get when not pushing on the spindle sideways.
I sent a note to AVID support and they replied that they measured a few and that is typical and not indicative of worn bearings.

So you’re gonna have to sell those GMT’s I guess :frowning:

I need the magnet with my CNC Depot spindle?


Only the GMT spindles. The others can be grounded by different means.