Repair of 1975 Gibson J-45

If you have a string instrument of any kind that needs fixing, a mistake you made in building a new instrument that you need to "disappear," or a question about the ethics of altering an older instrument, ask here. Please note that it will be much easier for us to help you decide on the best repair method if you post some pictures of the problem.

Re: Repair of 1975 Gibson J-45

Postby Barry Daniels » Wed Oct 03, 2018 12:14 pm

And then I discovered this ugly mess. I knew there would be some damage from the previously moved pin holes, but the bridge was resting on a thick bed of glue. It looks like the glue is at least 1/16" thick and thicker in some spots. This is not good. I may have to resort to serious top repairs now. I will see what it looks like after a liberal application of De-Glue Goo.
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Re: Repair of 1975 Gibson J-45

Postby Barry Daniels » Wed Oct 03, 2018 12:38 pm

Also, here is a frequency spectrum of the guitar with the original bracing. The neck and bridge have been removed. I am no expert on interpretation of these graphs, but the blue line shows the guitar with the soundhole plugged with a foam insert which cancels out the body resonance (110 Hz) and the contribution of the back. The gap between the red and blue line around 230 to 240 Hz is the back's interplay with the top.

I am using a free software program called Room EQ Wizard and a USB microphone to make this plot.
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J-45 original bracing, no bridge.jpg
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Re: Repair of 1975 Gibson J-45

Postby Barry Daniels » Fri Jan 18, 2019 1:12 pm

Well, fast forward a few weeks and this is where I am at: new top; binding replaced; finish on top and binding sprayed and curing.

One new shop addition is the bathroom exhaust fan installed near the top of my spray booth. I let it run full time to remove the off-gassing lacquer fumes during curing to keep them from getting into my house. It seems to be working well.
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Re: Repair of 1975 Gibson J-45

Postby Bob Francis » Fri Jan 18, 2019 4:06 pm

That is looking really nice Barry.
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Re: Repair of 1975 Gibson J-45

Postby Mario Kessels » Mon Jan 28, 2019 3:40 am

Great repair. Nice to see the use of the copper sticks, I always dislike the use of my SM steam needle ans was wondering if it would be worth changing to this kind of operation.
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Re: Repair of 1975 Gibson J-45

Postby Gordon Bellerose » Mon Jan 28, 2019 10:48 am

Even though I didn't get to see pics of the top removal, I have enjoyed this thread immensely.
Nice job on the burst! Better than new.
I need your help. I can't possibly make all the mistakes myself!
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Re: Repair of 1975 Gibson J-45

Postby Barry Daniels » Mon Jan 28, 2019 11:27 am

Thanks guys.
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Re: Repair of 1975 Gibson J-45

Postby Chris Vallillo » Tue Jan 29, 2019 6:51 pm

Barry, Outstanding work! Thanks for sharing.

I turned down working on an orange label Gibson Dove with almost the identical neck twist about 6 mos ago. The guitar was in beautiful condition but the neck was terrible. It's great to get insight as to exactly what it would have taken to do the job right!
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Re: Repair of 1975 Gibson J-45

Postby Greg Steil » Tue Jan 29, 2019 7:14 pm

boy I would have run away from this job FAST
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Re: Repair of 1975 Gibson J-45

Postby Barry Daniels » Wed Jan 30, 2019 10:35 am

Greg, I am doing this more for the challenge instead of a shop money maker.
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Re: Repair of 1975 Gibson J-45

Postby Barry Daniels » Tue Feb 05, 2019 10:44 am

I want to bounce a quick idea of you'all. I am getting ready to reattach the reset neck. I normally remove the finish from the top under the fingerboard extension. But after working with new nitrocellulose binding glued with titebond and an acetone wipe, I am thinking of doing the same thing on the top. I know that the nitro finish will soften up after being wiped with acetone. And the titebond should be able to get sufficient grip for this low stress joint. And before you get concerned about the titebond, I am only going to be using it for the extension. The dovetail will have hot hide glue. So what do you guys think? I guess I could try a small piece of wood to see how it works before I commit to the real thing.
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Re: Repair of 1975 Gibson J-45

Postby Bob Gramann » Tue Feb 05, 2019 11:14 am

It’s a low stress joint, but you never know what someone is going to do with the guitar. I used to glue down the tongues with plain old Elmer’s because it would release so easily with heat. But, I had a couple come up. So, I started using Titebond—it releases pretty easily with heat—and that problem went away. I don’t use HHG on the tongue because I want something that releases easier. I always glue to bare wood. If the nitro came loose from the wood and stuck to the glue when the tongue lifted, you’d have a mess to clean up. In the long run, I’ve never seen gluing to finish work well.

You have a lot more experience than me (working on build #130 and only sporadically do repairs), so you’ll have to weigh my opinion against that.
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Re: Repair of 1975 Gibson J-45

Postby Barry Daniels » Tue Feb 05, 2019 7:45 pm

Bob, you are probably right. I went ahead and scrapped the top down. Thanks.
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Re: Repair of 1975 Gibson J-45

Postby Barry Daniels » Wed Feb 27, 2019 8:04 pm

Just to tie up this thread, here is the completed project. Turned out good and the client was very happy. It certainly turned out to be a massive project, but the wall hanger can now be played.
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Re: Repair of 1975 Gibson J-45

Postby Bob Gramann » Wed Feb 27, 2019 8:51 pm

That’s a beautiful job!
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Re: Repair of 1975 Gibson J-45

Postby Gordon Bellerose » Thu Feb 28, 2019 12:59 pm

Barry, Nice Work!

Were you able to hear a difference in the sound of this guitar, with all the changes in bracing you did?
I need your help. I can't possibly make all the mistakes myself!
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Re: Repair of 1975 Gibson J-45

Postby Barry Daniels » Thu Feb 28, 2019 1:28 pm

Thanks guys. The final guitar sounded very good. Unfortunately I was not able to hear the guitar when it came in for repair because the neck was so twisted that it was completely unplayable. The bass strings were about 1/2" above the frets. I can't imagine that it's tone was very good though due to the really heavy bracing and the big honking bridge plate. My new top with the light scalloped bracing probably was half the weight of the Norlin one. I did not get a chance to do a frequency chart on the new top, darn.
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Re: Repair of 1975 Gibson J-45

Postby Steven Smith » Fri Mar 01, 2019 1:11 pm

That looks really good Barry! I have an older J-45 I restored including a new top, mine is ready for finish now and I hope it looks as good as your's does when I'm done.
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