Originally Posted by
Glenn Howard
Ok, I just spoke with Phil at Teknatool, and he advised that neither the reversible version of the G3 or the version that requires an insert would support the reverse function if used on the Jet 1221VS. The reverse version (and the insert model with the IXNS insert version for that matter) has a grub screw that for the Comet, contacts the spindle in a non-threaded area. For the Jet1221VS, the grub screw hits in the threaded area and shouldn't be used.
He said that if you truly wanted to use the G3 with the Jet1221VS in reverse, he suggested using a plastic spindle ring (spindle washer), which may help to keep the G3 in place while using reverse. His logic was, with the spindle ring, you can get the chuck on a bit more snug than without it. He did say even then, you'd need to use care because there is still some risk the chuck could come unthreaded while used in reverse.