Both the lathe spindle and collet nut have a 5/32" hole to accept a "tommy" bar for extra torque when tightening/loosening collets and chucks. The 3 jaw self centering chuck came with a single tommy bar that is 3/16" in diameter. Since I like multi-purpose tools, I turned down the last bit of the diameter on 2 small 3/16" rods to 5/32 like so

Notice the awesome concentricity, I've got to resurface those jaws...

Obligatory action shot: