Posted by Rick Denney on February 21, 2003 at 09:54:55:
In Reply to: Re: Re: repair without unsoldering? posted by John on February 21, 2003 at 08:43:50:
The expandable barrel only pushes from the inside. With a dent ball, you hammer the high spots into the low spots while the dent ball is lifting the low spot. This moves the brass around instead of stretching it.
I don't think you'd be able to hammer into an expandable barrel (at least one that could expand enough to do any good), because I can't think of any way to design it that would not have gaps between the sections of the barrel as it expands. If you hammer into a gap, the low spots will just get lower. You would not be able to turn the expandable barrel as you go, either, which is standard practice with a dent ball. But those gaps are the big problem, it seems to me.
An oval ferrule really needs to be removed, rounded, and fit back onto the repaired branches. Depending on the instrument, the ferrules can be machine and very thick and strong, and likely to distort the thin branches when reshaped. You are correct that a Dent Eraser will be no use on an ovalized ferrule. I have the same situation on my Holton, and pulling the bottom bow really is the only way. When I had Lee Stofer work on it, he was actually eager to pull that bow and do some dent work, but I didn't give him enough time.
Pulling a bottom bow isn't that bad, and a repair technician who is reluctant to do it may be telling you something important about his confidence and skills. Pulling a bottom bow is one of the standard repair steps for tubas--I'd bet it is done on the majority of tuba repairs that include de-denting.
Rick "who thinks burned lacquer also isn't that hard to deal with unless you want perfection" Denney