Touch plate grounding issue

I have an avid 5x10 and used it for awhile as is and would use the magnet on the bit per usual.

Then I upgraded to a s30c spindle with cnc depot and when set up the grounding of the bit would go through the chassis of the spindle and frame so I didn’t have to use the magnet any longer.

Today I added a 4th axis avid rotary. When I went to find the Z with the touch plate it did not ground out and I had to hit stop quickly. When I touched the bit with the magnet to the bit it grounded and worked.

So what could have changed when I added the 4th axis or what do I look for in mach4 to get it back to grounding through spindle again.

I talked to cnc depot and they think it’s a question for avid and not them.

You shouldn’t rely on the frame to be your signal return. While the frame is generally electrically connected (the S30C spindle is), you’re relying on the bearings to not happen to be floating on grease etc. You could use an ohm meter to try to find out what connection isn’t, or run a separate ground wire from the electronics through the cable chains to the spindle… or just remember to hook up the magnet :wink:

Also, it’s critical that the touch plate not itself be touching anything metal when you use it, or it will already be “triggered” and not register a new touch.

Also, welcome to the community! :slight_smile:

The issue with using the magnet is that I can’t hook it up and zero every time the ATC switched tools

If you’re using the touch plate to measure tools after a tool change, what you really want is a toolsetter, which has the ground built-in. I use this: TS1000 Tool Setter – DrewTronics

Still want to know why it was working before I hooked up the 4th axis and now it’s not. What changed something in the software? Something in the wiring for the 4th axis?

It could be something as simple as “you bumped the machine”

Only an ohm meter can tell you what your situation really is.

No, the rotary setup doesn’t change the SW for the touchplate, or affect the opto isolated outputs of the touchplate. As stated above, you probably need to get out an ohm meter to see why you no longer have a connection to ground. You didn’t say specifically, but when you originally got it to work through the spindle, did you intentionally ground the magnet wire side of the connection to the chassis somewhere? It should not have worked unless you did that because the touchplate contacts are normally isolated. If you did make that connection, you might want to check it to see if it came loose.

Just for clarity, the S30 is NOT grounding through the frame. It is grounded by circuit through the top metal bearing and out to the VFD.

Also, Aluminum oxide and the anodization are not electrically conductive.

PS. A worn top bearing can also lead to a bad connection. I think somebody had a few post about that a while back.