Hey folks,

I'm finishing up a UCCNC retrofit on an MG103 and am in the process of wiring up all the original sensors and solenoids. My last task is to get the tool touch off probe talking to the new motion controller. The machine is a 6x12' with the 8 position carousel and a fixed touch off plate mounted between the spoil board and the rails. During the short period that I ran the machine on the existing M24 control board (just to confirm that it worked) I did not do a tool change nor set a tool offset using this fixed touch off point. Being that when I purchased the machine not working, and I never saw a tool change or touch off before purchase, I realize I have no idea how this is supposed to operate normally (and everyone here likely knows what the documentation leaves to be desired). It didn't come with any sort of grounding magnet or clip so I assumed that it was capable of doing its touch off without manual grounding of the tool. However as I attempted to fire the touch off sensor circuit today I realized that I can successfully complete a circuit from the motion controller to ground anywhere on the machine including spindle body *except* on the loaded tool holder.

Am I wrong in thinking it's possible to touch off a tool without using a ground clip or magnet?

The spindle is a Colombo 16hp for HSK63F tool holders. These have ceramic bearings. Reading the schematics and observing the wiring I see that there is a -24v going into the spindle in the same place the main power terminals attach. It is control voltage negative (#358 white and blue). I can't think of any reason for this -24v to be wired into the body of the spindle except for touch-off as the other sensors in the spindle have their own -24v, however I'm a rookie and could definitely be wrong here. I also see line #740 (red) which the schematic has labeled as 'surface block' that runs from the spindle/relay patch panel near the spindle assy back to the control board where it connects to the motion controller in parallel with the wire from the touch off plate. There is no surface block attached to this machine, nor do I see a place where it may have once been connected. The wire from motion controller to fixed touch off plate has a shielded cable with ground.

Anyone have a good idea of how these should wire up? I'm a bit lost.

Also I recognize my description is also pretty confusing but that's the best I can describe this. Any help is very welcome.