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Thread: A4 back side repair

  1. #1

    Default A4 back side repair

    Can an expert tell me this cost of this repair? I don't think I can just clamp and glue?
    no earlier repair has been done. thanks !
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  2. #2
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    Default Re: A4 back side repair

    To do it right, perhaps +/- $200, maybe a bit less if the pulled-out area will move back into shape without too much coercion.
    That's using hot hide glue for the repair.
    If you haven't already done so, you should loosen the strings immediately.

    Also, there is a top brace located just behind the soundhole. It should be checked to make sure that it is not loose.

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  4. #3
    Registered User sunburst's Avatar
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    Default Re: A4 back side repair

    As rcc56 said, it sort of depends on ease of alignment for gluing, but when alignment is easy I charge for glue joint repair the same as I do for simple crack repair; by the inch. I think I'm currently at about $15 per inch, so measuring the opening will give you a ballpark... IF the rest of the glue joint is sound. The first thing to do (for the repairman) is apply light pressure to the ends of the separation with a thin blade to see if adjacent areas pop open easily. If so, it can turn into a bigger job. Likewise, if alignment is difficult it can become a difficult job.
    So, it can be a "simple" re-glue or it can be a more difficult and time consuming job, and someone qualified will have to examine it in hand and give you an estimate (guesstimate).

  5. #4
    Registered User David Houchens's Avatar
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    Default Re: A4 back side repair

    It may be just me, but it looks like the end pin has been pushed way in t o the tapered hole. I wonder if the tailback is split. Something looks odd to me.

  6. #5
    Registered User sunburst's Avatar
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    Default Re: A4 back side repair

    I was thinking it is a broken-off end pin. Not sue what's going on there.

  7. #6
    Registered User David Houchens's Avatar
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    Default Re: A4 back side repair

    Lol there's something going on with my typing too.

  8. #7

    Default Re: A4 back side repair

    No damage at endpin i pulled the broken one out.

  9. #8
    Registered User j. condino's Avatar
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    Default Re: A4 back side repair

    $15 per inch for hot hide glue work?????

    I need to raise my prices!

  10. #9

    Default Re: A4 back side repair

    Can someone share how to get the side and back to line up better? I guess the back and sides have gotten out of sync. Here is a photo of me squeezing it together.
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  11. #10
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    Default Re: A4 back side repair

    Misaligned joints require some method of pulling the instrument back into shape and holding it in position until after the glue is applied, the joint closed, and the glue has set. Sometimes it can be done with the clever use of cauls and auxiliary clamps, sometimes a special jig will have to be made.

    In extreme cases, a more drastic method borrowed from violin repair may be necessary. But since it is quite difficult, risky, and therefore not for people with limited experience, I won't go into it here.

    Bear in mind that if you try this repair yourself and it doesn't work out, it will be much more difficult to fix it right, may significantly increase the cost of the repair, amd might compromise the long-term reliability of the repair. If you use any other glue than hide glue and it doesn't go together right and hold, all bets are off.

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  13. #11
    Registered User j. condino's Avatar
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    Default Re: A4 back side repair

    There are a lot of ways to equalize the tension on a 'teens A mandolin. I do it often enough that I built this jig a few years back.

    Needless to say, it gets a LOT of use.....
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    Registered User sunburst's Avatar
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    Default Re: A4 back side repair

    Quote Originally Posted by j. condino View Post
    $15 per inch for hot hide glue work?????

    I need to raise my prices!
    I looked it up (my prices are all in the computer because I can't remember them and I tend to quote people 10 year old prices) and I'm actually still at $12/inch. I also tent to discount repairs involving a lot of crack length.

    To the OP,
    It looks like it will be fairly easy to get good alignment for someone with experience and a "torture rack" of some sort. Previous caveats are to be headed: unless you can get near perfect alignment and clamping and can glue it with hot hide glue, please take it to someone qualified.

  16. #13

    Default Re: A4 back side repair

    Quote Originally Posted by j. condino View Post
    $15 per inch for hot hide glue work?????

    I need to raise my prices!
    I worked for a shop doing vintage instrument repair. The owner's main focus was building custom instruments and finish work. He charged prices that I would be embarrassed to ask with a straight face....BUT, he had a beautiful website with all the prices displayed, so the customer was braced in advance. Besides working with pros and collectors, we also did a lot of "found grandpa's old guitar and want to get it restored" work. In the latter case, most of the customers were clueless as to what guitar repair costs. He paid me 70% if those prices, which was still more than I would charge on my own.

  17. #14
    Registered User j. condino's Avatar
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    Default Re: A4 back side repair

    I did a major restoration on an old double bass earlier this year that had almost 27 linear foot of cracks that were repaired. I had one in the shop a few years back that had several hundred cleats installed....

    So how much would you have charged to put Big Mon's old mandolin back together?

  18. #15

    Default Re: A4 back side repair

    According to an old friend, regular polishing of Japanese swords has held steady at about $100/inch for decades. The optimum process, beyond the rituals and specialized graded abrasives, is intended to reveal the metallurgical contrast from the hardening process. A cynic would suggest that it could be done a bit more easily, sans the 10 year apprenticeship.
    And, pray tell, what drastic assault on a bent violin consists of.

  19. #16

    Default Re: A4 back side repair

    What about humidifying to try to help? would that be done directly to the area of concern. Hard to know if the back has shrunk or the sides have expanded..it's just a tad off not allowing back to line up enough to go over, I guess some little lip.

  20. #17
    Registered User sunburst's Avatar
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    Default Re: A4 back side repair

    Humidifying might help, but probably not. If it is kept in 50% relative humidity for a few days that's about all you can do. Many of these old Gibsons have backs that are flatsawn and are shrunken from their original size when they are at proper moisture content. Sometimes the resulting error at the glue joint must be averaged out in the "torture rack" because exact alignment is no longer possible. I suspect some were made while the moisture content of the wood was still too high (it was a factory with production numbers to meet, after all). Wood movement puts quite a bit of stress on the glue joints in these mandolins and can be a contributing factor in, if not the main cause of open glue joints.

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