Maghee sent me four wooden fixed axle yo-yos that were in need of repair. One Apollo had the axle snapped completely in half while the others were worn and had lost most of their strength.
To repair these yo-yos I first cut their existing axles in half and machined them down to be flush with the body. Then the body was drilled out and threaded inserts were fitted. The result is a take apart wooden yo-yo with a replaceable TMBR axle.
To continue exploring the measurements and design of various yo-yos and parts: TMBR axles measure about 1/4" in diameter, have a 0.525" length, and are drilled with a 9/64" bit for a 6x32 axle.