Gibson non-tapered neck dovetails...Aaargh!
Hi Frank,
I'm a full-time instrument maker/repairer and amp tech working in New Zealand. I've found much interest and help in your frets.com pages over the years and I'm pleased to discover this new frets.net forum. I'm not sure what I can usefully contribute, but perhaps a little story might save someone from taking on a time-eater job like this one.....
My current least-favourite job in the workshop is a neck reset on a Gibson 12-string which turned out to have one of those parallel-sided dovetails. A pain to steam out, and when I did get it out, it appears to have been shaped badly during original assembly, then cut back to a straight tenon and had new 'wings' glued on with PVA glue, before being fitted to the body. Also this whole joint only extends about 2/3 of the body depth; the bottom of the heel is just butt glued to the body in some places, and gaps and wood filler in others.
Over several years, the original dovetail wing repairs done with PVA glue have shear-slipped, allowing the neck angle to shift...I And it is really no surprise to find this instrument with its bridge shaved down to half the original height, and still an uncomfortably high action.
I guess I _could_ have just trimmed the heel to adjust neck angle, and glued the heel stub back into the body with epoxy... but I would not have felt good about it. What happens in 20 years time when the neck may need a further reset ? ( this is a 12-string with a big, lightly-built body, and it's quite likely to need a second neck reset eventually)
So I did it the hard way....I cut back the stub of the tenon as little as possible, to clean wood, and glued on pieces of mahogany to make a longer, and tapered, dovetail joint. These hidden repair joints won't creep over time - I used high-strength epoxy, and I also mortised and glued the side of each added piece about 10mm into the end grain of the heel.
All this work will be hidden when the neck is replaced on the body, but now I can do a regular neck reset job, with a regular tapered dovetail and a bit of hide glue. And if this guitar ever needs a subsequent neck reset ( which it probably will) then at least it won't be the PITA job that I had to do....
Perhaps the folks on this forum would like to discuss and define which eras of Gibson acoustics are likely to have this kind of non-tapered dovetail, so at least we'll all know which ones to avoid, or to quote an appropriate price for the possible work involved..
I'm a full-time instrument maker/repairer and amp tech working in New Zealand. I've found much interest and help in your frets.com pages over the years and I'm pleased to discover this new frets.net forum. I'm not sure what I can usefully contribute, but perhaps a little story might save someone from taking on a time-eater job like this one.....
My current least-favourite job in the workshop is a neck reset on a Gibson 12-string which turned out to have one of those parallel-sided dovetails. A pain to steam out, and when I did get it out, it appears to have been shaped badly during original assembly, then cut back to a straight tenon and had new 'wings' glued on with PVA glue, before being fitted to the body. Also this whole joint only extends about 2/3 of the body depth; the bottom of the heel is just butt glued to the body in some places, and gaps and wood filler in others.
Over several years, the original dovetail wing repairs done with PVA glue have shear-slipped, allowing the neck angle to shift...I And it is really no surprise to find this instrument with its bridge shaved down to half the original height, and still an uncomfortably high action.
I guess I _could_ have just trimmed the heel to adjust neck angle, and glued the heel stub back into the body with epoxy... but I would not have felt good about it. What happens in 20 years time when the neck may need a further reset ? ( this is a 12-string with a big, lightly-built body, and it's quite likely to need a second neck reset eventually)
So I did it the hard way....I cut back the stub of the tenon as little as possible, to clean wood, and glued on pieces of mahogany to make a longer, and tapered, dovetail joint. These hidden repair joints won't creep over time - I used high-strength epoxy, and I also mortised and glued the side of each added piece about 10mm into the end grain of the heel.
All this work will be hidden when the neck is replaced on the body, but now I can do a regular neck reset job, with a regular tapered dovetail and a bit of hide glue. And if this guitar ever needs a subsequent neck reset ( which it probably will) then at least it won't be the PITA job that I had to do....
Perhaps the folks on this forum would like to discuss and define which eras of Gibson acoustics are likely to have this kind of non-tapered dovetail, so at least we'll all know which ones to avoid, or to quote an appropriate price for the possible work involved..
Views: 364
Replies to This Discussion
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Permalink Reply by Frank Ford on
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Yes, indeed, it would be good to have a comprehensive listing of Gibson's neck joints. They range from well crafted to some of the most incompetent! Me, I wish I'd kept better records in years past. . .
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Permalink Reply by Bob Gaddis on
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I have a Guild 12-string in my shop that I have been procrastinating a neck re-set. I'll be able to document what I encounter once I get up the inspiration to begin, but I hear they are not fun....
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Permalink Reply by Greg Mirken on
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I was afraid of Guilds, too. I don't have nearly as much experience with them as Martins, but I've found them to be well-fitting, cleanly machined joints. There's less taper than Martins, so your shims need to be paper-thin, and there's some finish touch-up involved. All in all, less of a deal than I thought.
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Permalink Reply by David Newton on
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In the dim recesses of my memory is a Gibson with the top wood covering the dovetail joint, then the fretboard glued over.
What!?
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Permalink Reply by C Herb Hickman on
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Quote: "In the dim recesses of my memory is a Gibson with the top wood covering the dovetail joint, then the fretboard glued over." Endquote
From the description this sounds like some that were done long ago and I think mainly pre-War. I knew about it or learned of it when I tried steaming a 1948 J-45 that would not come apart. As a precaution, I followed somebody's suggestion to saw through the middle section of the 15th fret, between the hollow cavities on either side of the dovetail. In other words, between the two holes I had drilled to inject steam and vent steam. That tactic is to cut the top spruce at the point it was (possibly) holding the dovetail in. An 8-mil thick saw blade was used, sawing through the bottom of the fret groove.
In my case (1948 J-45), the dovetail was NOT closed in by the top. The joint had just been fitted VERY tight originally, and took a really scarey amount of force to break loose. Traces of old glue were very scant in the joint, as if the builder was running out of hide glue and just fitted the dovetail joint so tight it was in there 'til hell froze over. A very nice joint, too, with very good dense mahogany neck and heel.
But none of that had anything to do with a parallel, non-tapered dovetail. I'd like to hear more common discussion of Gibsons in the 1970s-80s era with that paddle construction and very short dovetail. Got one of those to deal with some day.
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