Acoustic neck reset

Over the past month I’ve been working on a massive acoustic neck reset project. This one was a real doozy: the top was severely warped, several braces had come loose, the neck was severely underset, the fingerboard was coming loose from the neck… the whole thing was falling apart in my hands. I anticipated that this guitar would be a headache, but I had no idea how much it was going to fight me every step of the way. Normally my turnaround time is just a few days, but this guitar was in my shop for over a month (mostly waiting out the humidification process and for glue to dry). I’m happy to say that after a vicious battle, I have emerged victorious over this cantankerous Guild. Huzzah!

Acoustic guitars usually need a neck reset every few decades or so, as the string tension pulls the neck forward which causes the action to creep higher and higher. This Guild was about 20 years old, and was severely dried out, which may have caused the neck to pull forward earlier than usual. The top had also collapsed near the neck joint, but had severely bellied at the bridge. The top was extremely warped – which is usually very hard to photograph, yet it was so severe that it’s obvious even in pictures:

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I told the owner, Ron, that this could be a huge job, but he really loved the guitar so we went ahead with the work. Since the guitar was extremely dried out, I opted to humidify the instrument for two weeks before proceeding. I loosened all the strings and stuck a wet sponge in a plastic bag inside the guitar and then put it back in it’s case and let it sit for a bit. After two weeks the top seemed to have flattened out a bit, so it was time to get down to business.

The top was still heavily warped, so I opted to remove the bridge and heat press the top. Fortunately, Guild built this instrument with hide glue, so getting it apart wasn’t terribly difficult – just apply heat and slip a knife into the glue joint, and carefully remove the bridge. While I was at it, I also removed the original celluloid pickguard, which had shrunk considerably, and I suspected it had also played a part in warping the top, by pulling on the wood as it shrunk.


Before heat treating the top, I reglued several loose braces inside the guitar (no pics of this, as I couldn’t get any good shots inside the guitar). Then to flatten the top, I heated up a set of Thompson Belly Reducer cauls and clamped those down to the soundboard where the bridge used to be, and let that sit overnight. I had to do this process three times before I was satisfied with the top’s shape.


With the top back to a reasonable degree of flatness, I reshaped the bridge to perfectly mate with the top and glued it back down.


Some other guitar tech at some point had installed a JLD Bridge Doctor in there at some point, which is designed to help flatten warped tops and reinforce them against string tension –  but they had installed it incorrectly, and it had broken due to the strain. Not helpful, dude!


I fixed the Bridge Doctor, installed it correctly, and then plugged the bolt hole with a matching piece of rosewood.

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Ok – now that the top was flat and the bridge was reglued, now the real work could begin. Time for the neck reset!

Acoustic neck resets are among the most difficult tasks a guitar tech is required to do, and Guild guitars are probably the most difficult to do a neck reset on. Man, am I a glutton for punishment or what?

Getting the neck off on a Guild can be tough, but with the right tools and know-how, anything is possible. I start the process by removing the fret right above the dovetail joint that joins the neck to the body, and drilling a couple of holes through the fretboard down into the joint.


Then I heat the section of fretboard above the body and separate that from the body with a small knife:


Then comes the fun part: steaming the neck off the body. I’ve modified a Earlex steam generator to accommodate Stewmac’s steaming needle, and man, let me tell you: it’s awesome. Way better than using a espresso machine or pressure cooker – I get consistent steam with no sputtering, nor running out of water and having to start over.


I clamped up the guitar in my neck removal jig, inserted the steam needle into the aforementioned holes in the fretboard, and gently removed the neck:


The neck came off mostly clean-ish, so I let it sit for a day to dry out before carrying on. The next day I cleaned up the glue on each face of the neck joint, and got to work carving the heel. Shaping a neck heel is a slow, tedious process – it’s imperative that it’s absolutely perfect. There’s several issues at work that prevent this from being a quick job: the surface that the neck’s heel mates to is curved, not flat; the neck has to be shaped for not only angle, but also side to side pitch and twist; and string tension changes everything. I first made some calculations based on some measurements I took earlier,and determined I needed to take off about 2mm off the heel. In guitar tech terms, that’s a lot. I marked out the 2mm line on the heel, and then started shaping the heel with some chisels and a sanding block I made to match the dovetail.

IMG_2431 IMG_2433IMG_2434Once I had taken the heel down a bit, I clamped the neck back on, strung up the guitar, and checked my work… and then took it all back apart and shaped the heel a bit more. I must have done this process 15 times or so! After several hours of carving, I was satisfied with where the neck lined up – the neck angle was dead on, the strings were centered, and the action was good. Right on!

Next I shored up the dovetail to ensure a tight fit. I wasn’t just going to let glue do all the work – I wanted a tight mechanical joint that would require minimal glue. I glued on some mahogany shims to the side of the dovetail, and sanded them flat, and continually checking the fit so the neck would hold even without glue. Again, this required putting the neck on and then taking it back off multiple times, but anything worth doing is worth doing right, even if it seemingly takes forever (although I will admit cursing helps pass the time).


Ok, I had a good tight fit and a good neck angle – so I dry fitted it and checked one more time before I glued it up. Satisfied with this, I glued it up and clamped it, and let it sit for three days:


Now that the hard part was over, it was time to get my end game on. The fingerboard tongue had to be reglued, but since the neck was now pitched much further back, there was a sizable gap between the fingerboard and the guitar’s top (this is normal after a neck reset). So I measured the gap, and made a solid maple shim to fit under the board, utilizing some metal feeler gauges and my trusty belt sander.

Measuring the gap:


I cut a piece of maple, taped it and the feeler gauges to a block, and shaped it on the belt sander:IMG_2439 IMG_2440

I slipped the maple wedge under the fretboard, glued it, and then did some final shaping with a file:


Phew! Neck reset complete! Of course, after going through such dramatic and invasive surgery, it was no surprise that the neck needed a refret, so refretted it with stainless steel frets, made a new bone nut and saddle, and gave it a complete setup. Now it plays and feels like a million bucks, and it sounds better too (due to having proper downward pressure on the now taller saddle). There were a ton of details and headaches that I omitted here – if I had explained every tiny little detail I’d never finish this blog post! Suffice to say that this was an enormous job for me, and I’m really happy with how it turned out. Thanks, Ron, for your patience! I hope you enjoy your resurrected guitar!

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