TromboneChat

Photo of the Franken Olds F section https://photos.app.goo.gl/ZJT8PL7hveiAV8av5
thinking about easy (and not so easy) ways to improve the wrap.
two things:
1) not tunable
2) all those tight bends can't be good.

For the tunability problem I'm thinking of modifying the approx 3" radius bend to be tuning slide rather than soldered in. Assuming I could find any suitable tubing that would match up to the Olds. Supposed to be 0.510" bore. Interesting that the straight tubes as a bit larger OD than the bends. The straight tubes ar 14.9mm OD, the bends are 13.8mm OD. That's the 'easy' fix.

Or maybe replace it all with 1/2" ID soft copper!

That wrap is tunable. The large loop moves. It's marked for 1/2 an E pull. On some A-20s and the V-20 and R-20 the inner loop pulls as well and the combined distance gives E. My older A-20 did not have the pull on the inner loop.

I think your best upgrade would be to graft in the attachment tubing from a King 3BF or King 605F.

Well thanks much Bruce! With heat from a torch, I was able to get the inner loop loose. Still working on the large loop.

blap73 wrote: ↑Sun Dec 04, 2022 4:23 pm...all those tight bends can't be good.

Give it a try for a while before you start cutting and cooking. If you do decide it needs to be opened up, you can probably cannibalize most of what you need from a derelict A-20 in someone's parts pile.

BTW: Nominal bore on the f-attachment should be .515" (at least according to the Olds catalogs I've seen).

Updates
Moved the 3D printed linkage from the front of the brace to the back so that the horn can fit in the case I found.

Swapped the bell to a surplus King 606 bell, for 3 reasons:
1) Bell to Slide clearance was very tight with the Conn Director Socket and the Olds bell
2) Tone (or at least the feedback to me) was not to my liking. Found it hard to play.
3) Was tiring to hold given the weight. The bell swap (8.5" to 8" bell, thinner metal) dropped 1/4 pound.

So the current setup is:
Conn (late/brass 0.500") 18H slide and bell socket
Olds valve, F-section, tuning slide
King 606 Bell

To do: I lengthened the bell shank a bit to mount the bell closer to a 'normal' location, and as a result the insturment is *just* in tune with the tuning slide full in. The tuning slide ends had been mangled by rough use anyhow so I'll be cutting 1/4" off them to fix both issues.

https://photos.app.goo.gl/DdjB6BhkyswFDqk66