Gibson back removal

[Doug Cannon]

Hi everyone,

    Having recently re-inherited a 1980 Hummingbird that I'd given my younger brother in 1985, I'm in the process of reversing thirty years of damage. I have always done the basic work on my own guitars and am quite comfortable with taking on this project despite not having served an apprenticeship with someone.

   The odd paddle-shaped dovetail neck has been steamed off and I've decided that I could do a more thorough repair of the damage by removing the back to perform a series of repairs to the bracing and bridgeplate....both have failed leaving a bellied top and a bridge that slants drastically toward the sound hole. There are thankfully no cracks on the top or sides (small miracle) but there are four smaller grain cracks on the back that can easily be cleated after bringing the guitar back to a normal humidity level (it was never in its case, I'm told). The guitar neck was reset at one point and definitely needs to be reset properly as well as refretted (I've done refretting several times).

    I'd greatly appreciate advice on the best and cleanest way to remove the back with the least amount damage to the finish. I have seen many tops removed online but none to a guitar with the synthetic binding and purfling that gibson uses. I've made a template of the back out of 3/4 mdf to make reassembly easier and think that I have all of the tools needed to do this job, whether using a squared point "shoe knife" (seam knife) to separate the binding from the sides, or possibly another way. 

    I'd considered working on the guitar through the sound hole originally but believe that I could improve the overall sound of this overbraced "Norlin" by scalloping and tapering some of the existing structure while in the process of repair  and regluing.....I might be too optimistic....but  I'm not afraid of trying.

Thanks for any and all advice......

[Doug Cannon]

And a few more pictures of the poor bird....

[Dave Richard]

There is an excellent repairman in Western Massachusetts, Harry Becker. He has an informative website, with photo essays on repairwork.  One of them illustrates the removal of the back, from a '60's Epihone flattop.  Very clean job, requires the routing off of the back bonding(no finish damage).  Seems like a good method.  Google 'Harry Becker guitar repair', or 'William Cumpiano and Harry Becker'.

I see some cracking of the binding in your Hummingbird photos, so it might be tough to salvage the binding, anyway.  Good luck!

[Doug Cannon]

Thanks so much for the reply, Dave! I'll check out his website, it should be very informative. The cracking on the binding is only affecting the lacquer and not the binding itself, though I really am not  worried about replacing the binding if push comes to shove. 

Thanks again!

[Frank Ford]

As you work on this one, I think  you'll find that the binding is nearly completely decomposed, and at that stage where it is cracked all the way through from outgassing and loss of plasticizers.   Won't be all that long before pieces crumble out, so I'd count on losing the binding and replacing it, particularly if you take the back off.

[Doug Cannon]

Thanks, Frank...Upon further inspection of the binding, it does have cracks that go all the way through it and so I may just score the side of the binding and route it off leaving the purfling to be removed  removed separately. Do you know whether heat helps to remove the purfling? I'm not sure what glue Gibson used in 1980 but hope that it doesn't behave like an epoxy.....I've also touched up many of the noticeable but not deep scratches with Lacquer retarder and a fine brush.....worked extremely well....I know it's cosmetic, but it was quick, fun, and painless..... and good practice....

[Doug Cannon]

Hi Frank, 

Just a quick update on back and binding removal on 1980 Gibson Hummingbird. I decided to route the plastic binding off after lightly scoring the sides with a knife. I left 1/32" of the binding, as seen in picture #1,  and will eventually reroute to full 1/4" depth when the top is replaced. Given the slight arch of the back as opposed to the sides, I scraped the remainder of the binding up to the purfling wherever it needed to expose the kerfing (and bracing ends). This will allow me to remove the back with the purfling completely intact. I found that the binding hadn't decomposed and scraped off in long thin ribbons. Only the lacquer was cracked as it turned out, but I'm glad that you gave me the heads up on this as I approached the routing with great care! I used a very sharp small paint scraper and a 1/2" chisel for the scraping which couldn't have worked better for me 

Today is back removal and the beginning of all of the internal brace repairs and removal of the two layers of failing bridge plates left by "quick fix" repairs (not mine). While I have the back off and the bracing exposed I may consider tapering a bit of the bracing to resemble earlier model Hummingbirds. I have a call in to Ren Ferguson who I knew through a close friend. He knows a bit about the older models  (as opposed to this Norlin era on) and might be able to tell me if this would make any appreciable improvement with the quality of the guitar's sound. I'm curious what you might think, as well, as Gibson really seemed to overbrace this model (double X) with very little tapering. I'm not looking to change the bracing scheme, just the tapering if anything at all. Nothing extreme.

Thanks again,

Doug

[Dave Richard]

I don't believe 60's 'Birds had tapered bracing; just light, straight bracing.  I would consider removing the secondary 'x', and replacing it with tone bars, like the originals. Try to find photos of original 'Birds, or other early '60's Gibsons, with the back removed, to study.

[Doug Cannon]

Thanks Dave,

I'm going to cross my fingers on that search and hope that I can find some reference. I like your idea and you're right about the tapered bracing. I'm going to try to stick to the older bracing pattern if I can find it. I also found that most of the X bracing had failed, which explains the problems with the bridge and belly of the guitar. Should be a lost of fun.....

[Doug Cannon]

Removed the back off of the Hummingbird today....I am really glad that I chose to do this. There is absolutely no way that I would have found or been able to repair  what needs to be done through the sound hole. Repairs that were done in the past compounded many of the issues, not to mention over eight different bracing failures in the double X-bracing and two bridge plates ( the original was maple and the second (glued on top of #1) was 3 ply maple plywood. Someone tried to repair one of the main diagonal braces by literally slathering wood glue (PVA) on it....it didn't hold....Needless to say, there is a laundry list of things that I need to do before buttoning it up again and I'm really excited by having open access to work on them. I'll post a couple of pictures and start re-laminating the spruce around the bridge plate area in the morning. Also going to get to use hide glue for the first time tomorrow (I'll practice on some scraps first) and repair some of the easy cracks first.

[Dave Richard]

On the UMGF(Unoffficial Martin Guitar Forum), there is a 'Library of Gibson Bracing', a collection of photo postings of...vintage Gibson bracing.  I can't remember if there is actually a 'Bird', but there are examples of late '50's/early '60's Gibsons. Other square shouldered models)models(SJ, Dove, or their Epi counterparts(Frontier, etc) would have the same bracing, if you can find one to examine.  Gibson pioneered their square shouldered line with the production of square shouldered Epis in '58, predating the 'Bird.

[Doug Cannon]

Thanks so much, Dave!

I saw this last night and even found a bracing pattern for a 60"s Bird and pictures that corroborate it.....It seems that the only major differences are the two extra side braces at the top (free of the kerfing) and the bottom large "X" would need to be replaced by two diagonal main braces....Even the Gibson forums are not very forgiving about the Norlin era "X" bracing and maintain that this was cost saving implementation to eliminate warrantee repairs...in other words, build it like a tank and you'll never see it again once it leaves the factory.

[Dave Richard]

It is very, very helpful, IME, to examine 'hands on' the guitar in question, i.e. a early 60's 'Bird.  With mirrors and lights, look closely at and measure(as far as possible) the bracing dimensions, positions and angles of the various braces. Gibson changed their bracing, in subtle(and obvious!) ways, through the late 50's, early 60's, and late '60s(not to mention the periods before 1955, and (gulp) after about '67, and once Norlin took over.

A friend has a pristine '64 'Bird, which I've played and examined many times. It's worth having a look at one, if you'd like to capture that distinctive sound(and with the back off, you could really do it).