A crack question

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by marlin, Jan 7, 2008.


  1. marlin

    marlin Member

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    Hi everyone! My first post here, great forum. I just got this guitar and discovered this small crack where the tuning machine is. The threa hole is damaged and is twicw as big as it should be. My question is how would you fix this? I don't have any good lutheris around. I saw some posts abut super glue but i would need to "refill" the hole in some way for the screw to work. Thanks!
    [​IMG]
     
  2. rooster

    rooster Member

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    Were it my guitar, I'd get a small dowel, drill it and plug it, cut it flush, then re-drill a new screw-hole. StewMac sells a little jig to help keep the holes lined up properly for drilling the anchor screws for tuning machines. Wish I had had one years ago!

    rooster.
     
  3. marlin

    marlin Member

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    Thanks rooster, is it this jig you mean?http://www.stewmac.com/shop/Tools/Jigs/Tuner_Pin_Drill_Jig.html

    Is there something that can be used to fill the crack? At least a bit.
     
  4. sleis

    sleis Member

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    If the crack looks like it might spread at all, I would probably try and seep a little glue into the crack by opening it up a tad and getting some glue in and then clamping it tight. For the screw hole I would either do the dowel plug trick, or use some glue and sawdust in the hole and see if that holds. I would personally start with glue and sawdust for that small of a screw.
     
  5. marlin

    marlin Member

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    Ah, great idea with sawdust! Yes i feel a bit worried about drilling in there, maybe the laquer will crack and chip a big chunk?
    What kind of glue do you recommend? The superglue can be rather nasty and smear (at least for me) :\
     
  6. Scott Auld

    Scott Auld Staff Member

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    how can there not be any good luthiers around?
     
  7. marlin

    marlin Member

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    I live in a wierd place in northern scandinavia. I'd have to send the guitar.
     
  8. rooster

    rooster Member

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    The problem with the glue-and-sawdust approach is that you will most likely have to drill a hole for the screw, which will most likely NOT be in the exact location as the one you just filled. The drill bit will MOST PROBABLY "walk" into the original hole. A dowel can help minimize this.

    Oh, and the jig you included the link to is indeed the one I was talking about.

    rooster.
     
  9. Mike9

    Mike9 Supporting Member

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    From looking at the damage that guitar fell over, or otherwise took a shot to the headstock. Personally I'd weep some thin crazy glue into the crack then glue a tooth pick into the screw hole. Then after everything is good and cured just line your tuner up with the other side - you know so it looks right and tighten the bushing down and make a new hole with a thin awl, or 1/16" drill bit. Then use some wax, or soap on the screw threads and screw her home by hand with a #1 screw driver - not a drill. You'll be good to go as they say and you don't need any fancy tools for a repair like that. Just remember - YOU CAN DO IT ;)
     
  10. marlin

    marlin Member

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    Thank you all for your great tips!
    I think I'm going to get hold of a tiny piece of mahogony and make a small toothpick out of it. Then glue it together like you said Mike. I feel a bit uncomfortable with drilling a bigger hole and use a dowel pin. I could just "remove" the old threads from the misplaced hole to make it round and stick the toothpick in there with glue.

    I am not sure what "crazy glue" is though. Is that similar to super glue? Is this the glue: http://www.krazyglue.com/ ?
     
  11. John Phillips

    John Phillips Member

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    Make a piece of mahogany that's a good fit in the hole - shave it down carefully with a craft knife until you can feel it sticking tight when you push it in all the way.

    The best glue to use is superglue - it's extremely good at soaking into fine cracks like this. Put a drop or two in the hole, and wait several seconds, then put your piece of wood in, tap it into the hole - this will hopefully open the crack very slightly and allow the glue to penetrate fully - then clamp the headstock across its width to compress the repair (obviously, protect the sides of the head with something soft like softwood or folded card).

    When it's all dry, cut off the excess wood, put the tuner back in the right position, tighten the front collar to hold it, and then carefully drill a new screw-hole in the center of the hole in the tuner. A 1mm diameter is the size you need, so you'll be best with a hand drill. Don't go in too far!

    Put the screw back in, and make sure the front collar is tight - and check all the others while you're at it, it's possible that this happened because the collar was not tightened properly, rather than it taking a knock. Many aren't from the factory for some reason I've never understood.
     
  12. drfrankencopter

    drfrankencopter Member

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    I've had success repairing stripped holes with epoxy and release agent.

    Chase out the threads of the stripped hole with a drill, mask off the surface of the guitar, coat the screw in release agent, fill the screw hole with epoxy (maybe use the back end of the same drill bit you used to chase the threads out to push the epoxy down to the bottom of the hole). Wait for the epoxy to partially cure, then thread the screw in.....wait until the epoxy is almost fully cured, then remove the screw. When dry, flush sand any epoxy that protrudes from the hole.

    This will give you a thread that is far stronger than the original one... probably overkill in a tuner screw, but works great for neck bolts.

    cheers

    Kris
     
  13. marlin

    marlin Member

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    Thanks all for all your tips, this is certainly the place to ask questions! I have been to the shop today and got superglue, epoxy, wood filler(dunno about this but it sounds good, mahogony color), drill etc. I'm testing some of it now on a pice of wood to see how it turns out ;)
    Gonna let it harden over night and then i'll give it a try tomorrow. Thanks!
     

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