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Thread: Holton Double bell

  1. Holton Double bell

    Just starting in this forum, so here is a greater explanation. I have a 5V Holton double bell that was purchased several years ago with the wrong valve pistons (my epic fail). I am hoping to manufacture pistons from silicone-graphite rod, but am concerned about getting the port holes right. Is there any resource from the engineering of the pistons "out there"? Would I be better off having a shop custom build the pistons? I suspect the cost of building 5 pistons might exceed the value of the repaired horn. Help and/or suggestions are most welcome.

  2. #2
    Join Date
    Jan 2006
    Location
    West Palm Beach, FL
    Posts
    3,141
    Hi, and welcome to the forum.

    I think your statement, "I suspect the cost of building 5 pistons might exceed the value of the repaired horn." is accurate. I couldn't imagine where to start as the ports need to be smooth with gentle turn and perfectly aligned.
    Rick Floyd
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    "Always play with a good tone, never louder than lovely, never softer than supported." - author unknown.
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  3. #3
    You need to be aware that valves are hollow tubes, not rods. A valve is made from a heavy-walled tube for starters. Holes are drilled where all the visible ports are. Then smaller brass tubing is bent into shape to wind up as a tunnel between pairs of holes. The small connectors are called caucades, and they look like the knuckles you might have seen if you watch videos of horns being made. Each valve slide starts with a 90-degree bend (usually). That is a small tube that connects a short extension from the valve casing to the long valve slide tube. A caucade looks like that, but the bends are more gradual. Once the valve is made, then a heavy cap is put on top and threaded for the valve stem. A cap goes on the bottom, recessed from the end a bit. Then a large hole is drilled in the center of the bottom cap and a smaller hole in the top cap somewhere that is outside the perimeter of the washer/cork that fits on top. The top-bottom holes are necessary to let air flow through as the valve moves up and down.

    HOWEVER, are you sure it has the wrong pistons? If they are not installed in the correct order the horn will not work! Usually 1 & 3 are very similar, although even mixing those can cause trouble. Mixing the others can stop air from flowing at all.
    Last edited by davewerden; 10-06-2015 at 11:55 AM.
    Dave Werden (ASCAP)
    Euphonium Soloist, U.S. Coast Guard Band, retired
    Adams E3, Denis Wick 4AL (classic)
    Instructor of Euphonium and Tuba
    Twitter: davewerden
    Facebook: davewerden
    YouTube: dwerden
    Owner of TubaEuph.com, DWerden.com

  4. I had tried all of the pistons, even trying to match the stamped number (on some) of the pistons to the valves. I got ahold of a small mirror to check alignments, but if they might align in the open position, they wouldn't in the down position. If I proceed, I will probably dis-assemble the valve cluster and one by one try to cut the holes in the Teflon rods and then insert tube for strengthening the opening. It will probably end up as a retirement project. Does anyone know of old drawings of the engineering layouts for pistons?

  5. #5
    I'm just trying to rule out the easy stuff first!

    As far as ordering the valves, usually there is a number stamped into the top. If not, then study each casing in reverse order. Valves 4 and 5 will have the simplest arrangement. Look at where the tubes enter the casing and leave as a starting place to figure out which valve goes where.

    Alignment is controlled by the cork/felt on top of the piston (at the base of the valve stem) when the valve is up. When it is down, alignment is controlled by the cork/felt under the valve button (finger button). To make sure that is correct, take off the button and put the pad around the stem, put the button back on, and push the valve down to get the pad in place.

    Or have you already been around the block with all this?
    Dave Werden (ASCAP)
    Euphonium Soloist, U.S. Coast Guard Band, retired
    Adams E3, Denis Wick 4AL (classic)
    Instructor of Euphonium and Tuba
    Twitter: davewerden
    Facebook: davewerden
    YouTube: dwerden
    Owner of TubaEuph.com, DWerden.com

  6. Yes I have been 7/8 around the block. The numbering on the pistons was inconsistent (not matching or close to the serial number) even as to the piston order (1-2-3-4-5). When examining the piston in the casing, a few holes might line up, but frequently they were off by more than the pad or cork thickness, and some even appeared to be rotated (as if the valve guide was wrong). It would be tempting to go to instrument repair school and make this a project, but that is more dream than reality. Anyone interested in purchasing this "as is"?

  7. #7
    Because of this discussion I decided to do a blog post on how pistons are made. If anyone is interested it is here:

    http://www.dwerden.com/forum/entry.p...stons-Are-Made
    Dave Werden (ASCAP)
    Euphonium Soloist, U.S. Coast Guard Band, retired
    Adams E3, Denis Wick 4AL (classic)
    Instructor of Euphonium and Tuba
    Twitter: davewerden
    Facebook: davewerden
    YouTube: dwerden
    Owner of TubaEuph.com, DWerden.com

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