Posted by Lee Stofer on October 26, 2003 at 14:35:35:
In Reply to: tuba bending posted by builder on October 26, 2003 at 13:04:17:
Bending of tubing works pretty well, under the proper conditions, for tubing under 1" in diameter. Larger branches are generally made by (1) cutting brass sheet from a pattern, shaping the two halves, brazing them together, then doing a lot of intensive finishing work (the old-fashioned way), or (2) bending smaller, annealed (soft) thick tubing, then hydraulically blowing it up to size in a succession of iron molds with 2,200 PSI water pressure. When speaking of a hand-made instrument, this mainly refers to how the branches were formed.
Tubing must be annealed, then filled with lead or pitch to withstand bending, and then has to be hand-hammered to remove wrinkles afterward. Other work may be necessary also to complete the job. The primary bending jig in my shop consists of several different-sized, radiused holes drilled into a 2 X 6, that I insert into the large vise for stability. There is an art to tubing bending, and it is better to approach with caution.
Lee Stofer