Ended up having a customer that was interested in having a 3 piece tunable Bb whistle made in Delrin, so got to work on making something a little different and new.
Many years back (10+) I had fiddled around with some 3 piece designs which basically used a tenon to connect the two body tube sections. With lower key whistles, and in particular metal whistles, this worked fine since you could make a fairly tight fitting joint without too much trouble. When it came to higher pitched that gap between toneholes started getting mighty small, which didn’t leave a lot of options. I had seen and experimented a little bit with making a longer tenon and drilling the toneholes through it, but it always seemed pretty sloppy to me and of course made it fairly difficult to perfectly align the pair of holes without impacting the note that it fell on (and often times the next note above it). Also tried very short tenons, but it wasn’t very to keep those tight fitting and to not have any wobble in them (which led to squeaky notes and more potential for wobble with wear).
So the newest little workaround for this ended up being some machined out threaded inserts, and they came out pretty darn good I think. Took me a little while to relearn how to do all the fine pitch threading on the lathe again since I hadn’t messed around with any of that for again 10 or more years, but after a handful of attempts the inserts were coming out pretty consistent and reproducibly.
Here’s a video demonstrating the whistle made with them:
