TubeNet

I am restoring a large BBb Martin, 3p on the side, from the RMC era of the early 60s, 3/4" bore, 24" bell. The open horn notes throb like a brontosaurus in heat, but many other notes are stuffy. While snaking out deposits of greenish crust, I looked down the tubes into the piston bore to see that the pistons don't line up with the slide tube holes, at all. They look to be way off, like 1/4" off. The picture below shows the crescent-shaped outline of the piston hole. This can't be right, can it?

It would seem that the piston stems need to be longer. Maybe there's an excessive amount of spacers...

Any advice is appreciated.
Walter

Its possible you have trumpet stems instead of tuba stems !

check to see if you have the correct valve caps and fingerbuttons. Some fingerbuttons have a step on the underside that basically makes the stem longer. Also... on some of the Martins... I've seen situation where the valve caps bottom out on a ridge on the OUTSIDE of the casing instead of a the underside of the cap sitting down on top of the casing. Both of these things can cause an error when applying the correct felts and corks.

It is downright uncanny that you posted this very recently. A customer of mine just picked up his Martin tuba just a few hours ago. I also ran into the same problem with the valve alignment and independently came to the same solution as Bloke. Allied sells brass rod of the same size as the stems. If you drill it out and use an American 8x32 tap, it should screw right onto the button. You will need a piece somewhere between 1/8" and 3/16". This depends on the size of felt you are using, of course. There is plenty of thread left on those buttons, so you won't need to do any soldering at all. I definitely noticed a difference with the correct alignment.

Martin Wilk also fabricated bits for me. He does excellent work.

Ben Creswell
Grady Instrument Service

Here's a picture of the valves on my mammoth Sousa. I have two other top-action martins like yours (ones valve section is off it because I'm experimenting with making it a front-action). The stems look very modified. An original stem should fit in the small threaded hole inside if the added ring. I can measure the stems on my horns if you wish. Yes, those are Yamaha finger buttons. They work well on martins. So do kanstul tuba buttons.

Walter, got a picture of the whole horn?

Bob Kolada wrote:Walter, got a picture of the whole horn?

Bob, see Walter's post from when he picked up this great horn.

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