Changing bumpers on a rotary

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Salazarsam33
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Changing bumpers on a rotary

Post by Salazarsam33 »

Hello fellow tubists,

I have decided to change my tubas stock silicone bumpers to some good neoprene bumpers, Tom at mack brass advised me to use 3/16th rubber stop cord.

I changes them, and due to their size I did not have to cut them out, but I noticed the alignment in the back might be 1 or two hairs off (yes a tiny bit off, but it is distinguishable to the naked eye) because the seem to be a tiny bit too small. Will this affect the intonation or playing?

I did try to fix the problem by making the bumper longer so the upper part of the linkage bumps into the rubber faster, and therefore fixes the alignment problem. Is this an okay thing to do, or will this affect the linkage? Or is a tiny bit off aligned better?

I know this may sound really weird and specific, I'll try to take some pics and post about what I am talking about, but if anybody could advise I would gladly appreciate it.
Wisemann C
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Salazarsam33
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Re: Changing bumpers on a rotary

Post by Salazarsam33 »

I also bought 1/4 just in case the 3/16th was too small, it is hay to large however and I would have to cut a decent amount.
Wisemann C
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Re: Changing bumpers on a rotary

Post by Heavy_Metal »

Salazarsam33 wrote:....... I noticed the alignment in the back might be 1 or two hairs off (yes a tiny bit off, but it is distinguishable to the naked eye) because the seem to be a tiny bit too small. Will this affect the intonation or playing?
It can, and in my experience, generally it will make the affected notes play sharp. Not long ago I tried a Miraphone 190 on which a couple bumpers were badly worn, and its intonation was horrible. In an Alexander-free world I would want a 190, but not in that condition. Once it was fixed it sold very quickly.
Principal tuba, Bel Air Community Band
Old (early 1900s?) Alexander BBb proto-163
1976 Sonora (B&S 101) 4-rotor BBb
~1904 York 3P BBb Helicon
Old Alex Comp.F, in shop
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