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repair a body crack

Discussion in 'Hardware, Setup & Repair [BG]' started by luzceloffan, Feb 26, 2013.

  1. hi guys! A friend asked me to paint his old yamaha rbx 250 bass. When I stripped the components noticed a crack going from the vol pot hole to almost the jack hole, i dont want this crack to break the paint later, since it has a relief and its also present inside the control cavity. I was thinking to route the crack and fill with epoxy. Any advice?
  2. SirMjac28

    SirMjac28 Patiently Waiting For The Next British Invasion

    Aug 25, 2010
    The Great Midwest
    Ouch ! I hope someone comes along and helps this man out.
  3. FatherG


    Dec 16, 2009
    The woodworker in me says to route the crack and replace it with a piece of wood (that can be sanded & filled if necessary to match the body surface) and glue a piece on the inside that spans the interior of the cavity and the replacement shim - glue that piece so that the grain runs perpendicular to the shim's grain.
  4. hi FatherG, english is not my mother tongue, so when you say that i should glue a piece that spans the interior of the cavity and the shim, you meant a piece that fills the cavity and then re-route the cavity?
  5. FatherG


    Dec 16, 2009
    No, just a thin piece that will provide support for the shim.
  6. oh! I got it, thanks a lot. Will start to work on it. Much appreciated
  7. Bruce Johnson

    Bruce Johnson Supporting Member Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    If I were repairing that, I would use a hard marine epoxy like West Systems, reinforced by a little piece of fiberglass cloth on the inside of the cavity. I wouldn't rout out the wood.

    Wipe some wax on the paint surrounding the crack, but don't get any in the crack. Then put a piece of wide masking tape over the area, covering the crack.

    Now turn it over and work from the inside. Put some masking tape dams in the pot holes to try to keep out the epoxy out of the holes. It's not a big deal if some leaks in; you just have to clean it out with a file later.

    Apply the epoxy from the inside. Dab some on the crack and let it sink down in. Keep adding more until the crack is filled up. Then spread some around and lay down the piece of fiberglass cloth. Spread some more epoxy on top of the cloth to get it saturated. Use a scrap of cardboard to smooth it down and keep it from being too thick.

    As an alternative to the fiberglass cloth, you can cut and fit a thin aluminum plate, and epoxy it down inside the cavity. That will reinforce the whole controls area structurally, plus provide some shielding and grounding.

    After the epoxy is cured, pull off the tape on the outside. The epoxy should have filled the crack right up to the surface, and hopefully didn't ooze out anywhere. From there you can lightly scrape it smooth and touch up the paint, or just leave it as a thin "scar" line.

    Did I mention that you should do this operation on top of a sheet of waxed paper? Epoxying your bass down to the table is embarrassing. I've done it.
  8. Hopkins

    Hopkins Supporting Member Commercial User

    Nov 17, 2010
    Houston Tx
    Owner/Builder @Hopkins Guitars
    What Bruce said, there is no need to rout that area out.

    The fact that the crack runs between the holes is a good thing. It wont spread any farther than it already has. I would cut about a 1/8" thick by 3/4 wide piece of maple just long enough that it fits between the pots when installed and glue it to the inside of the cavity with Titebond wood glue. You should be able to use a couple of blocks on the top and inside of the cavity as a clamping caul, and clamp with C clamps. Just make sure you sand any finish off of the area that is going to be glued.

    After sanding the finish off of the cracked area, flood it with thin CA glue until the crack is completely filled then block sand the CA back until it back to bare wood, so the CA only remains in the crack. You should have a nearly invisible repair when finished even if going with a natural finish.
  9. awesome tricks dudes, thanks a lot for your help!