Hey AntMan,
I assume you are talking of Buildbotics.com-derived Onefinity CNC Controller.
Yes it’s true, it has already been covered and you would find it in the forum with the search function:
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Because your spindle is grounded, then you need only the wire leading to the 3-Axis Touch Plate. Unlike when using the router, you now do not need the magnet end of the touch plate anymore. But in most cases the cable is wired the wrong way around. See here for details.
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Be absolutely sure that your spindle is grounded through the fourth (PE) wire of its motor cable, otherwise you have a strong safety problem. Although the machine chassis has to be grounded, including all moving parts, the spindle should NEVER be grounded through the chassis! The only correct way to ground the spindle is through the PE wire in its motor cable that is connected to VFD ground (⏚) (usually in its grounded control cabinet), and from there it is connected to ground in the wall outlet or wall box.
Note that even if PE wire and cable shield are both connected to ground, they serve two different purposes. PE is crucial for electrical safety, and shield cannot replace the PE wire.
If you bought a cheap Chinese spindle, you should also be sure that in the spindle the PE (fourth) pin of the spindle socket is actually connected internally to the spindle housing, as seen here. You can check this with a multimeter (set to ohms/resistance, the resistance between the PE wire and the housing of the spindle must be close to zero).
IMPORTANT NOTE: I would strongly advise against making your own spindle cable without reading this document:
See here for details:
- The Spindle cable
- How to ground your machine
- Which Spindle Cable (DIY vs. ready-to-use)
Welcome to the forum!