Posted by John Swensen on August 30, 2000 at 14:52:03:
In Reply to: St. Pete "German Machine" posted by Chuck on August 29, 2000 at 15:32:15:
I have made a couple of key mechanisms (with linkages) from scratch, using only simple hand tools (hacksaw, file, drill, propane torch), and they both work very well. With the exception of the brass bar for the arms and main bar, the supplies can be bought in a model airplane hobby shop (a metal junkyard usually has some brass).
Building such a mechanism has very low risk, because it screws into place when done, and can be removed with no damage to the tuba if you don't like it.
I'm working on a writeup for the process, complete with pictures, but I would be happy to answer questions for the mechanically adventurous before the write-up is complete.