If I remember correctly, Julien or Will would be a proper source for this, the Shapeoko isn’t grounded.
If you have a search, there’s a few threads discussing grounding the spindle such as this one.
I’d defnitely look into some dust extraction, especially in plastics you don’t want to be re-cutting chips and melting them onto the cutter, it’s best to get them out of the way quickly. Before I had my extraction boot I just stood over the machine with the shop vac whilst cutting really messy stuff like plastics.