Post date: Jul 19, 2013 2:35:18 AM
With the whole "spindle shocks you when running" thing, I thought I'd crack it open and see what it looked like and search for an obvious solution. Fortunately (or not), the ground pin wasn't connected to ANYTHING. That's rather an egregious oversight in my book, but at least it's easy to fix.
After performing the modification, you can touch the case while it's running and not get shocked- definitely a plus.
Interestingly enough, the multimeter still tops out when checking the spindle case to ground voltage- even with its range set to 1000V, both AC and DC. I'm not entirely sure why that would be, since putting it into current-measuring mode and measuring the spindle case to ground current gives something like 90 uA. Still more than the 0 A I would like, but definitely nothing too extreme.
I also re-wired the VFD side of things, so now the shielding is actually connected to something.
Two side notes:
-I originally was going to solder the wire to the edge of the case, despite it being a giant heat sink. As you can probably imagine, that didn't work, even with a giant soldering gun.
-Taking off the top of the spindle doesn't expose the bearings or anything like that- so you don't need to worry about it falling apart and not being able to put it back together. You DO need to be careful enough to not rip off the motor wires, though.