Tutorial: threading trumpet MPC top with a tap

Tutorial shows how to cut the shank off a trumpet mouthpiece and then thread the top so it can take threaded backbores. This is a handy thing to be able to do. This is the "easy" way using a 3/8x40 "bottoming tap" to make the threads. the Hole needs to be .250 or .249 deep and .340 in diameter. There needs to be a tread relief groove also, and this shows how to do that. If you dont have digital readouts, you will need to measure several times a go of course. The tap is held in th etailstock chuck, and the whole tailstock slides on the bed as the tape enters the workpiece. Its almost as good as single point treading if you meticulously center the workpiece to the inside throat. ask questions if you like.