Wednesday, February 15, 2012

Bass Horn Part 3

Did some more work, well not much...

The rotor block and linkage has been giving me a lot of trouble. I had to use corrosion cracker three times under heat twice and about 5 days to free up the screws that held the linkage on the valve block. Once this was free, I unsoldered the braces, removed the tubing, and ultrasonically cleaned the valves and casings. No need for the tubing anymore!

Trying to figure out a way not to machine a whole bunch of new parts or trying to find parts to work, I looked at the linkage braces - these would work if I mounted them back on the valve block. I tried this, but soon discovered that, although the linkage hooked up with the stop arm on the rotor, it wouldn't fully depress. So now I either have to file off a millimeter or two from the braces or add a washer to each side to bring the linkage up. It should work since the distance between the "S" links and the stop arms doesn't change, just the height.

I had wanted to know where the valves needed to be and some length of the overall bugle, so I grabbed a F horn off the wall and started sizing things up to get the correct valve/left-hand placement. After that I started planning how I would add the extra tubing needed to drop the pitch to BBb. Unfortunately, this quick measurement gave me about 222" or 18.5 feet! And this was without a tuning slide! Now I'm going to have to readjust the open wrap in order to place a main tuning slide and still looks like a french horn.

Still need to find a leadpipe - it was recommended that I locate an Allied universal euphonium leadpipe, but I might have to have a custom leadpipe made to expand to the .687" bore needed for the main slide and the valve block. Also a mouthpiece that resembles a french horn mouthpiece but fits the bass trombone/tenor tuba shank receiver. Lastly a whole bunch of tubing to bend into shapes and most importantly ---- a collar and tenon for a removable bell!

Lots of work ahead....

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