Well this is all pretty overwhelming, particularly for someone who knows diddly about electricity.
The only ground rod I am aware of in my shop is the one the electrician drove into the ground through the concrete. Isn't everything else grounded via the third prong of a plug right into the electrical system of the building?
Isn't the ShopBot grounded simply by being plugged into its 220 outlet? I don't have any additional copper wires going from the machine to a ground. Never have.
If I disconnect the copper ground wire that currently runs from the DC frame to the ground rod, how do I ground the DC? (It's an Oneida Gorilla Pro, and it came with a ground wire that runs from the top of the motor and clips to the metal mesh frame around the filter, which has always been attached). Run a copper wire from the metal ductwork to electrical conduit on the ceiling?
The DC is literally a few feet from the ShopBot. Does that make the problem worse?