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Thread: Repairing a 1936 Gibson K-1 mandocello

  1. #26
    Registered User Jim Adwell's Avatar
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    Default Re: Repairing a 1936 Gibson K-1 mandocello

    If it is hide glue, heat and moisture (steam) will soften it. Without having the thing in front of me, I couldn't really say exactly how I would go about applying the heat and moisture. Someone that does repairs might be able to give you a better idea of how to proceed.

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  3. #27
    Registered User resophonic's Avatar
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    Default Re: Repairing a 1936 Gibson K-1 mandocello

    What would be the best strategy for removing the old brace do you think?
    Remove as much material as you can with a sharp chisel. When you get it really thinned down, start soaking it with hot as you can stand water using a sponge or rag. Shouldn't take long to get some edges to begin releasing to a point where you can start working a palette knife under it. Repeat until it's off. Clean up any boogers with a hot damp rag or light sanding. It's not necessary to remove all of the residual hide glue. It will re-activate and bond with the new glue job, assuming you will be using hot hide glue.
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    Certified! Bernie Daniel's Avatar
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    Default Re: Repairing a 1936 Gibson K-1 mandocello

    Ok this is my dry clamp arrangement just to see if my clamps will work. I intend to glue in the new brace tonight and then try to glue the back board on tomorrow. Thanks to all who helped out!
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  6. #29
    Mandolin Dreams Unlimited MysTiK PiKn's Avatar
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    Default Re: Repairing a 1936 Gibson K-1 mandocello

    Did you have to pad the clamps on the finished part of the top?

    = The Loar, LM700VS c.2013 = "The Brat"
    = G. Puglisi, "Roma" c.1907 = "Patentato" - rare archBack, canted top, oval
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    Resonate globally Pete Jenner's Avatar
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    Default Re: Repairing a 1936 Gibson K-1 mandocello

    Nice work Bernie.
    The more I learn, the less I know.

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  10. #31
    Certified! Bernie Daniel's Avatar
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    Default Re: Repairing a 1936 Gibson K-1 mandocello

    Quote Originally Posted by MysTiK PiKn View Post
    Did you have to pad the clamps on the finished part of the top?
    Good question and yes they are padded.

    I use about a 1/4" pad of rubber wine bottle cork epoxied on the part that touches the top of the instrument and the same thickness of cork cork on the part that contact the piece being glued. Just my opinion but I think the actual cork seats tighter on the wood and that the rubber cork is a better pad on the finish. Here is one of those black clamps with a 5" throat clamp.

    As you can see they are "industrial grade" clamps and I really dislike clamping all the metal mass to my instruments. I am going to look for some nice light-weight albeit deep-throated clamps if I start doing more of this repair stuff.
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    Default Re: Repairing a 1936 Gibson K-1 mandocello

    Quote Originally Posted by Pete Jenner View Post
    Nice work Bernie.
    Thanks Pete. Hey here is a short video of the mandocello before I glue the back on. I'm tapping on it with a little cork hammer and was curious to what folks thought about the tone. Be easier to correct BEFORE I glue that back on LOL!
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    Resonate globally Pete Jenner's Avatar
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    Default Re: Repairing a 1936 Gibson K-1 mandocello

    It sounds ok to me Bernie. I think it's wood for sure! I hope that helps.
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    Certified! Bernie Daniel's Avatar
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    Default Re: Repairing a 1936 Gibson K-1 mandocello

    Quote Originally Posted by Pete Jenner View Post
    It sounds ok to me Bernie. I think it's wood for sure! I hope that helps.
    Thanks. I played around with it a bit more and tapping over the bridge or on the bridge brace sounds like it has more life. In any case that is exactly the same approach that Frank Ford took and I don't know anyone who would know more about guitar or mandolin repair than he does I guess. So I'll glue it back on --hopefully.
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    Default Re: Repairing a 1936 Gibson K-1 mandocello

    Well it was not easy but the back is back!

    In the end after a lot of pressing and pushing the match up was very good and I doubt it will be very obvious that it was ever off. That is a big advantage of using fish glue you have up to 7 - 10 minutes before it starts to set.

    So that part (gluing) is good.

    But what will it sound like?

    It worked when it was done before on that K-2.............
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    Last edited by Bernie Daniel; May-31-2015 at 10:15am.
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    Resonate globally Pete Jenner's Avatar
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    Default Re: Repairing a 1936 Gibson K-1 mandocello

    It will sound like magic.
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  18. #37
    Certified! Bernie Daniel's Avatar
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    Default Re: Repairing a 1936 Gibson K-1 mandocello

    Well the patient seems to have survived the surgery!

    It is back together, strung up, and sounds pretty much like it used to -- based on my memory as it has been nearly 3 years since I played it. The volumes seems about the same (maybe a tad less?) and the sustain is excellent -- least as good as before the repair. I can't make good videos in the daytime as there is too much light in my office but I'll make one tonight.

    After removing the gluing clamps this morning I did find that the top must have expanded slightly while it was off for the week because there is one small (1") section that the binding is protruding about 1/16 - 1/32" beyond the side of the instrument. The only thing it hurts is my pride and it is not very noticeable.

    I had to do a lot or work on the bridge and set up this morning when I tried to string it up as the action was sky high -- the brace was keeping the top for settling like it had before it was glued in.

    Surprisingly there is still a little bit of top sag -- not under the bridge anymore but across the whole top -- it is not really very easy to see but I think this speaks to the fact that these old Gibson oval holes were certainly a marginal design as far as the top plate is concerned?

    Overall I think this turned out about as well as I could have hoped for all things considered. I appreciate all the help from this forum and also the Frets.net repair forum!
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    Default Re: Repairing a 1936 Gibson K-1 mandocello

    Nice one Bernie. Do you want me to look after those wine bottles for you? I promise I would take good care of them. Good wine needs to change hemispheres every few years.
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  22. #39
    Registered User resophonic's Avatar
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    Default Re: Repairing a 1936 Gibson K-1 mandocello

    That's Great Bernie, a virtual pat on the back for getting through a rather difficult process, a happy end to the story!

    Do you have enough back binding to scrape the protruding part of the back flush to the side? You might be able to improve the overhang a bit if not remove it.

    The entire top on any archtop instrument will give a bit under string pressure. Th re-curve around the perimeter is where the top is the thinnest, they are not all that dissimilar from a speaker cone design. Get some measurements of the string action, now that it is done and check it periodically. If it stays put, you can take it off of your worry list. May take a few days to completely settle in.
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    Default Re: Repairing a 1936 Gibson K-1 mandocello

    Quote Originally Posted by Pete Jenner View Post
    Nice one Bernie. Do you want me to look after those wine bottles for you? I promise I would take good care of them. Good wine needs to change hemispheres every few years.
    Sure Pete that is only one fourth of the rack I can spare that! It is not that I am addicted to wine (very much anyway) I just like to be prepared for any natural (or unnatural) disaster that might interrupt the supply lines.
    Last edited by Bernie Daniel; Jun-01-2015 at 12:58pm.
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  26. #41
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    Default Re: Repairing a 1936 Gibson K-1 mandocello

    Quote Originally Posted by resophonic View Post
    That's Great Bernie, a virtual pat on the back for getting through a rather difficult process, a happy end to the story!

    Do you have enough back binding to scrape the protruding part of the back flush to the side? You might be able to improve the overhang a bit if not remove it.

    The entire top on any archtop instrument will give a bit under string pressure. Th re-curve around the perimeter is where the top is the thinnest, they are not all that dissimilar from a speaker cone design. Get some measurements of the string action, now that it is done and check it periodically. If it stays put, you can take it off of your worry list. May take a few days to completely settle in.
    Thanks yes good thinking. When I first put the hardware back on and strung it up I could see that action (@12th) was going to be about 0.190" so I went to work on the bridge base and saddle. Now it is at 0.10" and still needs more work but I think I'll do like you suggest wait a week for it to all settle in and then do the final set up.
    Bernie
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  27. #42
    Mandolin Dreams Unlimited MysTiK PiKn's Avatar
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    Default Re: Repairing a 1936 Gibson K-1 mandocello

    Bernie,
    This thread, for me, is education.
    My old wrekky 'hotrod' mandolin, pure plywood, desperately needs an offset to severe top sag. It's a horrible cheap mandolin, nothing like the quality instrument you present here.
    But I have learned much already, and I thank you for an excellent presentation of your project and experiences, and also for bringing to this the experience of many others who have gone before.
    For me, it's a future project, and mainly for learning, since I don't expect great improvement on the old beast. (It's a safe learning ground.)
    Congratulations on your success. And thanks again for sharing this. I have bookmarked for future reference.

    Cheers.
    Myst

    = The Loar, LM700VS c.2013 = "The Brat"
    = G. Puglisi, "Roma" c.1907 = "Patentato" - rare archBack, canted top, oval
    = Harmony, Monterrey c.1969 = collapsed ply - parts, testing, training, firewood.


    "The intellect is a boring load of crawp. Aye. Next wee chune".

  28. #43
    Certified! Bernie Daniel's Avatar
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    Default Re: Repairing a 1936 Gibson K-1 mandocello

    Quote Originally Posted by MysTiK PiKn View Post
    Bernie,
    This thread, for me, is education.
    My old wrekky 'hotrod' mandolin, pure plywood, desperately needs an offset to severe top sag. It's a horrible cheap mandolin, nothing like the quality instrument you present here.
    But I have learned much already, and I thank you for an excellent presentation of your project and experiences, and also for bringing to this the experience of many others who have gone before.
    For me, it's a future project, and mainly for learning, since I don't expect great improvement on the old beast. (It's a safe learning ground.)
    Congratulations on your success. And thanks again for sharing this. I have bookmarked for future reference.

    Cheers.
    Myst
    Thanks. Good luck and when you get ready do it you will find many here ready to help with great advice!
    Bernie
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    Due to current budgetary restrictions the light at the end of the tunnel has been turned off -- sorry about the inconvenience.

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