lapping valves

Discussion in 'Trumpet Discussion' started by alant, Aug 15, 2011.

  1. rowuk

    rowuk Moderator Staff Member

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    Ivan IS the tech. I see no way that a valve can stick once it is broken in - UNLESS there is dirt, damage or distortion as when you play, there is a continuing wear. If a valve is so worn that the oil no longer provides a viscous shield, it can also stick. I consider that damage.

    Dirt is DIY. The magic marker will point you in the right direction for the rest. You can also look for scratches in the valve casing.

    Putting a valve in a different horn tells you nothing.
     
  2. ComeBackKid

    ComeBackKid Fortissimo User

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    A better indication of the problem area would be to remove all of the pistons from the cornet and then take the one piston that seems to be sticking and try it in the other two casings to see if it sticks there, too. Then try the other cornet pistons in the casing where the sticking piston goes. See if the sticking moves with the piston, or stays in the same casing.

    No two pistons are identical, whether from the same horn or different, but the pistons from the same horn are more likely to be close in their dimensions so using the ones from the cornet should give a better indication of what is really causing the sticking.

    Keep in mind that sometimes the sticking occurs only after playing for awhile which seems, in some cases, to be an accumulation of oil/saliva in the valve where the tolerance is so tight that it binds due to the accumulation. So, with all casings and pistons dry and clean, you may not detect the interference.
     
  3. tedh1951

    tedh1951 Utimate User

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    I would follow all the cleaning and magic marker advice here first - I would not lap anything - and I'm trained in lapping techniques.
    One solution I have found for problems like this has been to change to a quality synthetic lubricant - Ultra Pure is one such product that works for me, but after all the troubleshooting above has been attempted.
    I agree that swapping valves from one instrument to another is useless, it's like asking your wife to buy you a pair of nice shoes. You'll end up with red stilettos when you really need low healed beige courts. :-?
    Above all, remove NO metal - there's no way back.
     
  4. Trumpet Dreamer

    Trumpet Dreamer Mezzo Forte User

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    OK, the other end of the spectrum...I have a YTR-2335S that had a sticking issue (chatter) with the valves. I had them custom lapped by a local tech who is VERY GOOD at this sort of thing. Now, the horn plays like a dream. What was the genesis of the problem? Who knows! But it is fixed now and that is all I care about. No negative impact on the playing at all.
     
  5. SteveB

    SteveB Mezzo Piano User

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    Very true. Valves from two different horns, even if they are of the same make and model, will inherently have completely different size tolerances.

    A quality-built horn like a Bach Strad will have each valve precision-matched to its own valve housing. Matter of fact, swapping valves between horns could result in some expensive damage.
     
  6. Dave Mickley

    Dave Mickley Forte User

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    I'm just an old geezer but I would advise not to switch valves between horns and NOT to switch between valve casings on the same horn. When your horn was new the valves were lapped in at the factory and the tolerances are open enough that there could be a small difference between valves on the same horn, besides you will have slightly different wear patterns between valves because none of us push our valves down with a perfectly straight motion. again just ramblings from an old geezer.
     
  7. operagost

    operagost Forte User

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    I used this method to identify a valve guide that was jamming.
     

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