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Discussion in 'Setup & Repair [DB]' started by lowendgruve89, Mar 29, 2009.

  1. lowendgruve89


    Jul 20, 2008
    Fresno, CA
    How can I repair an endpin where the wooden ring has been stripped by the screw?
    I cant quite explain it....lthe wooden ring isnt cracked or anything, but the screw keeps on turning and wont hold the endpin in place...theres also a metal ring surrounding the wooden ring where the screw goes...

    I dont have money for a new endpin or money to take it to the shop.

    Sorry if the question is badly written.

    thanks. any help is appreciated. :)
  2. ctxbass

    ctxbass Supporting Member

    Nov 6, 2003
    Central Texas
    Best quick repair advice I've seen foir this problem:
  3. 1st Bass

    1st Bass

    May 26, 2005
    Forest Grove, OR
    The metal ring (or the screw itself) is what has the stripped threads, more than likely. Back the screw all the way out and look to see whether the screw, or the ring, or both are stripped.

    If the ring is stripped, you can go to the hardware store and buy a drill bit just large enough to remove all the threads in the original hole, and the correct size tap and driver to re-thread the new hole. Then get a hardened steel bolt to match that thread size and pitch.

    If just the screw is stripped, all you need is a bolt whose thread matches the thread in the ring.

    There is a type of hardened bolt that has a hex-key hole in the head, and evidently is meant for a set-screw of some sort-- it is black, and the threaded end of the bolt ends in a rather sharp ring. That would be the ideal choice, but I don't remember the correct name for them. The hardware people can also sell you a plastic knob that the bolt will thread through, so you have a handle to turn it with-- or you can make a nice wooden knob around the bolt head, and epoxy it together, if you are geared that way (I am, but that's me...).

    The thing is, most of the screw assemblies are made from fairly soft steel, and either they strip out, or the end goes dull and won't hold the pin anymore. The pins with the notches are nice, because that is not an issue.

    The whole hardware store trip including tools should be less than $25, I would expect. If you have a friend with a tap and die set, so much the better.
  4. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    That's called a "cup point set screw." When in doubt about anything involving machinery, ask a Wisconsinite. This is the sort of place where our master luthier shows off his nice Clausing lathe. :D

    The cup point has its pro's and con's. It grips the shaft by gouging into it. On the other hand, it's worth seeing if there is a root cause to the threads getting stripped. Is the end pin plain, or does it have notches cut into it? If it's a plain end pin, it will take a lot of force on the screw for the pin to stay put, and the threads will eventually strip out again.

    For this reason, any repair involving tapping out the metal ring (a good idea BTW) should also involve filing a notch into the pin if it isn't already notched. And if there is a notch, then a round point set screw will suffice.

    Note that there are "coarse" and "fine" threads for the US standard diameters, and fine threads are preferable here because the ring is probably rather thin.

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