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  1. #1

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    in progress


    from one of the top repair/refinishers around...curt of old school guitars

    pics so far- showing that sunken top can be result of/or result in- cracked bracing

    Old School Guitar Repair >> Gibson ES-175N that’s sporting the broken brace issue. (still in progress).


    cheers
    Last edited by neatomic; 09-18-2020 at 03:44 PM. Reason: pic-

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    The Jazz Guitar Chord Dictionary
     
  3. #2

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    Curt is a living legend he help me with a Gretsch repair I needed to do. I will never forget. Gave me the exact measurements I needed on the neck set. I did not use hide glue.............just don't tell him that.............He is pro!

  4. #3

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    One day I'll get round to getting the sunken top on my 1961 ES-175D seen to - for the last few years a sound post has been added and - so far so good - its holding up well and acoustically even appears to have more bass resonance than before the sound post was added......

  5. #4

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    Wow, that’s quite a far-reaching repair, taking the whole back off. Of course it’s the most thorough way of repairing but if the top has not sunk too much I have seen them get cranked up and a spuce slat being glued against/on top of the broken brace, which can be done without taken the whole back off. Which is a lot less intrusive of course.

    But your luthier apparently deemed it necessary, he will know best!

  6. #5

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    It must have been the weight of that useless bridge pickup that caused the damage.

    Let that be a lesson to everyone!

  7. #6

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    Interesting to see how the laminate will be re-formed. Some kind of press?

  8. #7

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    Most people would say that the older ES 175's were built better than the new ones. The ES 175 in the pictures have kerfed braces. Modern ES 175's including my 2013 model have solid braces. Ha ha.
    Last edited by Tal_175; 09-18-2020 at 06:32 AM.

  9. #8

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    I'd bet good money that the guitar fell over on its face...probably at a bar gig, or, when the owner got up from playing (guitar on stand/still plugged into the instrument cord) and started walking to get a beer in the fridge..foot tangled in the cord.

    I've had both mishaps occur--fortunately with a Telecaster.

  10. #9

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    Quote Originally Posted by Greentone
    I'd bet good money that the guitar fell over on its face...probably at a bar gig, or, when the owner got up from playing (guitar on stand/still plugged into the instrument cord) and started walking to get a beer in the fridge..foot tangled in the cord.

    I've had both mishaps occur--fortunately with a Telecaster.
    That was my initial thought as well. In the old days before guitar stands were available, most of us just leaned out guitars against an amp or chair between sets. And at home we leaned them against furniture. Both could lead to accidents as you've described.

  11. #10

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    while we’re here chaps

    how are kerfed braces supposed to work ?

    i understand the kerfing allows
    the brace to conform to the top ....
    but how does the kerfed brace
    help maintain the arch ?

    surely the kerfed brace has lost all its strength ?

    with a kerfed brace guitar ...is it just the glue on the brace that’s helping keep the arch up ?

  12. #11

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    Actually, if the builder filled the kerfs with glue the brace would be about as supportive as a solid brace.

  13. #12

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    I never understood kerfed braces. It just seems so....wrong!
    Anyway, this thread made me want to look at the braces on my '55 es 175 which has absolutely no sinking in the top.

    The braces do have kerfs, but they're about 4" apart.

  14. #13

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    Here’s a broken tonebar repair done without taking the back off:

    FRETS.COM Field Trip

  15. #14

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    Quote Originally Posted by Little Jay
    Here’s a broken tonebar repair done without taking the back off:

    FRETS.COM Field Trip
    It's amazing how that thin strip of spruce can hold the arch in shape under the force of the strings.

  16. #15

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    Hi, my friend neatomic suggested I wander this way.

    Yes the broken braces could have been repaired without removing the back but with limited access the stability over time was questionable with the kerfs. Additionally, a solid brace produces vibrations that a kerfed one could only dream of. Placing splines in the kerfs was another thought but the owner and myself wanted undisturbed wood. Not a biggie removing the back, actually it's a lot of fun.

    I'l be getting back to this on in a few days and will update the site.

  17. #16

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    Quote Originally Posted by Little Jay
    Here’s a broken tonebar repair done without taking the back off: FRETS.COM Field Trip
    . . . and this pic from that same repair shows why you want to practice clamping before any glue is involved -- a literal "dry run" :


  18. #17

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    Here's a situation where the replacement pickups were wider than the braces so they needed to be moved and replaced with 200 year old Douglas fir from the schoolhouse.

    https://www.oldschoolguitar.net/gall...eamliner-into/

  19. #18

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    Quote Originally Posted by CurtW
    Hi, my friend neatomic suggested I wander this way.

    Yes the broken braces could have been repaired without removing the back but with limited access the stability over time was questionable with the kerfs. Additionally, a solid brace produces vibrations that a kerfed one could only dream of. Placing splines in the kerfs was another thought but the owner and myself wanted undisturbed wood. Not a biggie removing the back, actually it's a lot of fun.

    I'l be getting back to this on in a few days and will update the site.

  20. #19

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    Quote Originally Posted by pingu
    while we’re here chaps

    how are kerfed braces supposed to work ?

    i understand the kerfing allows
    the brace to conform to the top ....
    but how does the kerfed brace
    help maintain the arch ?

    surely the kerfed brace has lost all its strength ?

    with a kerfed brace guitar ...is it just the glue on the brace that’s helping keep the arch up ?
    ( Simplified explanation!) The brace acts like a supporting beam like a floor joists. In simple terms the max stress is created at or near the centre of its' length. Under the downward force of the strings via the bridge, the top of the brace (glued to the top) goes into compression. The bottom of the brace goes into tension. Somewhere near the centre of the depth of the brace, depending on the shape of the cross - section, there is neither compression nor tension. It's the extremities of the depth of the brace that do most of the work in supporting the top. With a kerfed brace that is glued to the top, the compression stress is handled by the fact that the top is 'assisting' and stopping the kerf slots closing up under that compression. The thin continuous bottom part of the brace is expected to handle the tension. This principle is perfectly acceptable in structural design but in the case of a kerfed brace, that bottom part requires substantial continuous grain to withstand the tension stress. Ps there are other stresses generated, as well as the tension and compression, which only really become an issue when the glue breaks down.

  21. #20

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    The gaps are too wide for that to work. I understand the theory and it’s plausible but fails in execution. And I like my tone bars uninterrupted.

  22. #21

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    Quote Originally Posted by CurtW
    The gaps are too wide for that to work. I understand the theory and it’s plausible but fails in execution. And I like my tone bars uninterrupted.
    I prefer uninterrupted tone bars also.
    Do all kerfed tone bars fail in execution?
    If the glue is solid the gaps, regardless of width, can not compress at the top (ie where the bar is in compression). It's the integrity of the continuous timber at the bottom (which is in tension) which is crucial.

  23. #22

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    so great to have curt joining in!...check his gallery for some of his (well documented) & incredible work

    https://www.oldschoolguitar.net/gallery-2/

    his refinishing is as good as his repair work... he has an extensive background in paints and finishes

    he's a busted guitar miracle worker!

    cheers

  24. #23

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    I got intrigued and made this drawing for myself to understand how the forces in kerfed braces work:


    As long as they don’t become unglued and as long as the strength of the lateral connections between and on top of the kerfes is not compromised (by runouts in the wood for example) they should in theory be just as strong as solid braces I think.

  25. #24

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    Quote Originally Posted by Little Jay
    I got intrigued and made this drawing for myself to understand how the forces in kerfed braces work:


    As long as they don’t become unglued and as long as the strength of the lateral connections between and on top of the kerfes is not compromised (by runouts in the wood for example) they should in theory be just as strong as solid braces I think.
    Exactly.

  26. #25

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    curts finished the interior work...replaced the bracing..and has updated his link with new photo's

    Old School Guitar Repair >> Gibson ES-175N that’s sporting the broken brace issue. (still in progress).




    cheers