How to make a trumpet mouthpiece Backbore reamer pt1

This is part one of three parts.

Part 1 is how to copy an existing backbore by making the reamer on lathe
part 2 is hardening the mandrel
part3 is grinding the half-round cutting edge and sharpening it.


Making backbore reamers is one of the more difficult aspects of making mouthpieces, but as you can see it's not really that hard. The way i'm doing it here with the ink is a real good way to get a reamer to be the size and shape of another backbore. Of course you can create new shapes, or modify existing shapes etc, and also change the insertion depth to get various other sizes etc.



If you had a shop make one of these it would be expensive, and also if there was a curve or curves in the shape (generally there is) they just cant get it, cuz measuring and plotting seems like the way to go, but backbores are more subtle than that. A straight taper is easy enough (this particular one was the most "straight" that I've copied) for a machine shop, but getting the curve the old fashioned way is something they dont know. I tried hiring this job out to high end "aerospace and Bio-medical" CNC shop that routinely made some pretty amazing parts, and they simply could not do it. They tried pretty hard too, and I helped them out. They were trying to duplicate some of my reamers that needed to be replaced. When they asked how they were made originally they said no wonder. They tried using the probe method, which was really off, then plotted out using optical visualizer, and this method that im showing here was far superior. Maybe somebody out there can do it better with some technology, but it wont be cheap. If someone did it this way it would take about 1.5 hours of work including heat treating and grinding and sharpening. Maybe 2 hours including setup etc.