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repairing rotary valves
Posted: Sun Sep 30, 2012 11:44 pm
by OldHorn
I am repairing an old European F tuba, courtesy of our friends on EBAY. I've removed and reassembled a badly stuck 2nd valve slide, got out the remains of a headless mouse long pickled in spit & valve oil at the 3rd valve, and will glue on a new leadpipe soon (with solder). The valves were crusted up inside with crud that looked like scrapings off bad teeth. The .010" brass inserts were rotten and pushed out easily by hand, and were not soldered in. I would like some ideas on how to form, fit and install new inserts. The look like they have a slight bow shape. Any advice appreciated.
Re: repairing rotary valves
Posted: Mon Oct 01, 2012 1:32 am
by Dean E
Trace the outlines to form templates. Then, from the templates, scribe the outlines to sheet brass. Trim with good, sheet metal shears.
Use a wooden dowel (or deep well hex socket) slightly smaller than the bore diameter to form the cylinder with your fingers.
It will be very difficult to solder the inserts without warping the valve. Probably best done with a jeweler's oxy-acetylene torch--after lots of practice on junk parts.
Getting that valve round and properly fitting again is an expert-level job that probably will require trips to the plater's for copper and brass buildups before lapping using an old-school, split oak block.
Plan B--find a replacement valve from a junk horn, or Plan C, get a new replacement for an identical valveset.
Good luck.
Re: repairing rotary valves
Posted: Mon Oct 01, 2012 6:24 am
by hbcrandy
Send the valve set to Dan Oberloh and let him do it. He has done work for me in the past. He is QUITE good.