I'm a new hobbyist who recently took delivery of an AlphaCNC AMN-6040-M fixed-gantry CNC router for use in prototyping parts in 6061-t6 aluminum. So far the machine looks pretty solid but I'm having a few setup issues. The manufacturer is kind of trying to help, but language barriers, etc... It's been slow & frustrating. This is one of the setup issues I'm having:

Background-->

The Z-Axis calibrator I ordered with the machine isn't working. Luckily I tested it first! When I touch the calibrator to the spindle motor housing I see the 'Digitize' input go high in Mach-3/Diagnostics like I think I should, but when I touch it to the rotor / tool-holder, I don't get the 'Digitize' signal. This seems to indicate that there's no electrical contact between the spindle housing and the rotor. I confirmed this, my multi-meter reads OPEN CONNECTION when I check resistance between the housing & rotor. This isn't a multimeter or probe contact issue (paint, etc), I can read 0-ohms across the tool holder, etc.

Both the manufacturer (who obviously didn't test this before shipping the machine) and my local 'experienced friends' are incredulous and say "that's impossible! You should have contact thru the bearings (etc)". So I ask:

Questions-->

- The spindle rotor, and therefore the tool holder aren't grounded. How is it possible that there's no connection between the spindle rotor & the housing?
- Is the spindle motor defective? Is this a common issue?
- Or is the rotor typically isolated but is normally tied to ground via a wire but isn't here? (loose wire?)
- Is there any way to "manually" ground the rotor spindle?

Besides relying on the Alpha CNC guy, we're going on three weeks of emails on this and other issues with no good results so far, the only thing I can think of to resolve the problem is to hack around it by building or buying some sort of switch based Z-Axis calibrator.

I'm aware I could manually ground-clip the bit before using the Z calibrator but I'm planning on upgrading to an ATC and want to resolve the issue up-front if possible.

????*??