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PostPosted: Mon Jul 09, 2018 6:05 pm 
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Cocobolo
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I pulled the neck off of this dreadnaught to reset it.

I couldn't find the air pocket in the joint so I removed the fretboard at the 12th fret to see what I was dealing with and to make sure I had good gluing surface for reattaching the fretboard. The pocket was super small and full of glue so that's why I couldn't find it with my drill bit. Anyway the neck came off easily once the fret board was off. I re-glued the fretboard onto the neck, but now when I put the neck back into the pocket I have a gap of about .010, I can get that down to about .005 if I squish the neck back in with a clamp. Is this normal?


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PostPosted: Mon Jul 09, 2018 6:15 pm 
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The gap at the sound hole is normal.. When you reset the neck you changed the neck angle relative to the body. Most neck resets tilt the neck in the direction that will give you that gap. You can either accept the falloff and clamp it down or make a small wedge.

The gap at the join is not normal at the end you need to refit the dovetail.

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PostPosted: Mon Jul 09, 2018 6:18 pm 
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While that is normal for a reset in the picture it looks like the gap goes all the way to the end of the body (14th fret?) That tells me maybe the tenon isn't all the way down in the pocket.


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PostPosted: Mon Jul 09, 2018 6:30 pm 
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Brazilian Rosewood
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Part of a neck re-eset is getting the neck down to the top at the 12th or 14th fret. Check out John Hall's vid on dovetails...

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PostPosted: Mon Jul 09, 2018 11:01 pm 
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Cocobolo
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I haven't actually done anything other than take the neck off and re-attach the fretboard portion that I had taken off.

I'll check out John Halls videos, I've been using the Dan Erlewine DVD as a primary resource with this but I intend to dig into a few more resources before plunging off the point of no return.

Should the joint slide back together easily or should there be resistance the further in the dovetail goes?

My first thought was that there was something impeding the tenon from going all the way into the pocket, I pulled the neck back out and cleaned out anything that was loose (or almost loose). There still may be some obstruction, I"ll take a closer look tomorrow. I did squeeze the joint back together with a clamp and reduced the gap to .005 as I said, but the feeler gauge wouldn't slide all the way in, and light no longer shows when you look through the gap. Is it possible that I compressed the wood on the edge with the knife I used when heating the fretboard off so it appears that there is more of a gap than there really is?

I was also worried that maybe I messed something up when I re-attached the fretboard to the neck, causing the fretboard to sit above the body but there doesn't seem to be any gap between the rosewood and mahogany...


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PostPosted: Tue Jul 10, 2018 9:25 am 
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Brazilian Rosewood
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Think we all presumed you had started the reset. Has the joint even dried out? Are you sure? Is all the glue crap scraped/sanded out and off?
The joint when finished should be tight enough to be able to pick up the instrument by the neck. It should "tap in" with a few taps of the mallet. Make the wooden sanding block John shows...

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These users thanked the author Haans for the post: Pmaj7 (Tue Jul 10, 2018 9:53 am)
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PostPosted: Tue Jul 10, 2018 3:51 pm 
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Cocobolo
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Here's a couple pictures of what the neck looks like after re-gluing the fretboard. Does this look problematic?


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PostPosted: Tue Jul 10, 2018 4:10 pm 
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Cocobolo
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a more thorough cleaning of the joint, there was glue squeeze out in the corners, the remnants of a couple old shims, and other bits of debris I hadn't noticed and this is what I have now. Where the neck joins the body I can't even get a .002 feeler gauge in the bass side, the treble still has a small gap but not much more. Seems much more reasonable...


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PostPosted: Thu Jul 12, 2018 3:50 pm 
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Cocobolo
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Well, I took a little material off and shimmed the pocket and restrung but still needed to go a little further. So off with the strings, and I took a little more material off the heel and I'm about to shim the pocket a second time, but I want to double check my logic before moving much further, there is a slight gap at the base of the heel, it seems to me that the shim(s) will deal with the gap by forcing the base of the joint to suck further into the joint, but I have trouble forcing it closed by hand even if I push on the headstock. Is this remedied by the introduction of the shims or do I need to do more work around the heel? I've noticed that the joint is flush by the fingerboard but the gap develops towards the heel cap, does it just need more sanding near the fretboard?


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PostPosted: Mon Jul 16, 2018 2:30 pm 
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Brazilian Rosewood
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The gap on the fretboard extension looks to me to be a from the board curling. But it's probably a combination of curling and the new set angle. IF it is the set angle then you can simply make a shim for it. If it's cruling then if when you clamp it in place dry and there is no gap then just go for it. If not then you will probably have to sand it flat and probably do a refret.

You should be able to use the straight edge measurement to get the neck angle right. Just rest a straight edge dead center on the FB along the top of the frets such that it hangs over the bridge. Once the airspace there at the saddle is about 1/32ne inch (provided the bridge has never been shaved down) then you have the right angle.


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PostPosted: Mon Jul 16, 2018 9:00 pm 
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It looks to me like you have altered the angle by removing material from the bottom of the heel cheeks. Now the dovetail is no longer tight, particularly at the bottom. Generally you have to shim the bottom of the sides of the joint more than the top, I glue the shims in then taper them with chisels and sanding blocks. It helps a lot to chalk fit them - you can see where you need to take away material.

I also think you have confused things a bit when you sawed the f/b off - frankly I would have left that off until the neck was set, then tried to glue it back in place over the joint and onto the body.

A well made dovetail just sort of slides into place with no wobbling or other movement. Frequently I'll have to give it a slight tap with a plastic hammer to set it (and tap the heel to get it apart) but you can tell when the wedging action is working. From your pictures you are not there yet.

edit to add - I am not an expert at dovetails, I've only done a dozen or so and I fight them each time. John Hall's vids are really good for teaching how they work and how to set them, there are others that are helpful too. One of the things I found really helpful was putting too thick of shims in (just like a new joint where the neck stands proud of the block), then shaving them down and watching the neck drop into the pocket. I also had the advantage of learning on a few new guitars before I tried resetting one that was really wonky.



These users thanked the author Freeman for the post: Conor_Searl (Mon Jul 23, 2018 1:28 am)
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PostPosted: Mon Jul 23, 2018 1:33 am 
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Cocobolo
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Freeman wrote:
It looks to me like you have altered the angle by removing material from the bottom of the heel cheeks. Now the dovetail is no longer tight, particularly at the bottom. Generally you have to shim the bottom of the sides of the joint more than the top, I glue the shims in then taper them with chisels and sanding blocks. It helps a lot to chalk fit them - you can see where you need to take away material.


Thanks Freeman, I've been away for a week so just getting to this now. That's exactly what I've done, and figured I needed bigger shims than what I was trying, so thank you for the confirmation. I'm assuming by chalk fit you mean to apply chalk to the surface opposite the shim and then the chalk transfers to the shim as it makes contact showing what needs to come off?

Do you apply the shim to the dovetail or the pocket I've seen people do it both ways, the shim on the heel of the neck seems simpler to work with, but it seems easier to glue the shims into the pocket.

Freeman wrote:
I also think you have confused things a bit when you sawed the f/b off - frankly I would have left that off until the neck was set, then tried to glue it back in place over the joint and onto the body.


This is entirely possible, I thought I might need that part of the fretboard to figure out my neck angle properly. I've considered taking it off again and may end up doing that in the end.


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PostPosted: Wed Jul 25, 2018 10:52 pm 
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Cocobolo
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Location: Cowichan Valley, BC, Canada
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So I used oversized shims, and removed material from the shims until the dovetail fit. That's actually a really enjoyable and peaceful task. I used a clamp to seat the neck all the way in, and it was a nice tight fit and felt really solid, but I'm still left with a slight gap at the bottom of the heel, it's about .008 wide, and under string tension opens up to .013. As I said the joint feels really solid despite the gap and actually took considerable effort to get apart again, but it seems that the joint is either not pulling the neck all the way back to the body and I need yet more shim in the very bottom, or else in my trimming I inadvertantly took more material off the bottom than I did the rest, resulting in a slightly curved cheek? Is there another possibility that I'm missing?


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PostPosted: Thu Jul 26, 2018 8:38 am 
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Are you using the sandpaper strip technique to fit the cheeks of the heel to the side? If you're lifting up on the strip when you pull them then you could be sanding the heel at an angle. I can't see what you're doing so it's hard to tell.

Is this a particularly valuable guitar?



These users thanked the author DanKirkland for the post: Conor_Searl (Thu Jul 26, 2018 9:54 am)
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PostPosted: Thu Jul 26, 2018 9:57 am 
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Cocobolo
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DanKirkland wrote:
Are you using the sandpaper strip technique to fit the cheeks of the heel to the side? If you're lifting up on the strip when you pull them then you could be sanding the heel at an angle. I can't see what you're doing so it's hard to tell.

Is this a particularly valuable guitar?


I did use the sandpaper trick, I was careful to pull down towards the body rather than up and away so as not to angle the heel.

Not particularly valuable but interesting, a friend got it for $400. Hand made in the early 80's in Toronto. He gave it to me to learn resetting on.


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PostPosted: Thu Jul 26, 2018 1:03 pm 
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Cocobolo
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Location: Cowichan Valley, BC, Canada
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Country: Canada
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So I've discovered that the bottom of the dovetail joint is pushing up against the back of the pocket which is forcing my heel out and not letting it close. None of the things I've seen on neck resets, (John Hall, Dan Erlewine, Frets.com, etc.) mention this in their processes. It seems simple enough to take a little material off the back of the joint to allow space for the joint to pull back in. But I don't want to do that if there are unforeseen consequences. I don't know if the amount of space behind this joint is normal or not, but there sure isn't much room.


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PostPosted: Thu Jul 26, 2018 2:04 pm 
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Cocobolo
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Conor_Searl wrote:
So I've discovered that the bottom of the dovetail joint is pushing up against the back of the pocket which is forcing my heel out and not letting it close. None of the things I've seen on neck resets, (John Hall, Dan Erlewine, Frets.com, etc.) mention this in their processes. It seems simple enough to take a little material off the back of the joint to allow space for the joint to pull back in. But I don't want to do that if there are unforeseen consequences. I don't know if the amount of space behind this joint is normal or not, but there sure isn't much room.


I've removed a slight bit of wood on that portion of the heel on each reset I've done, moreso if the neck was severely out of whack. I can say from experience that the ones where there is no gap (filled with glue or just fit too tight) are the most nightmarish ones to work on, because when you remove a neck you need steam/heat to reach those portions of the neck, if it can't reach it then you have more problems.

Remember the sides of the tail are where you need the most glue surface. If you're changing the angle of the neck enough then it makes sense that the neck would fit in the socket like this.

Just remove enough that it leaves a slight gap at the bottom so that should the guitar even need another reset you don't drive the next guy up the wall with a dovetail that won't budge. I remember talking to a guy who specialized in cellos with my lifetime worth of experience. His advice on gluing things together was "Never make it undoable"



These users thanked the author DanKirkland for the post: Conor_Searl (Thu Jul 26, 2018 2:22 pm)
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PostPosted: Thu Jul 26, 2018 3:04 pm 
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DanKirkland wrote:
I've removed a slight bit of wood on that portion of the heel on each reset I've done, moreso if the neck was severely out of whack. I can say from experience that the ones where there is no gap (filled with glue or just fit too tight) are the most nightmarish ones to work on, because when you remove a neck you need steam/heat to reach those portions of the neck, if it can't reach it then you have more problems.

Remember the sides of the tail are where you need the most glue surface. If you're changing the angle of the neck enough then it makes sense that the neck would fit in the socket like this.

Just remove enough that it leaves a slight gap at the bottom so that should the guitar even need another reset you don't drive the next guy up the wall with a dovetail that won't budge. I remember talking to a guy who specialized in cellos with my lifetime worth of experience. His advice on gluing things together was "Never make it undoable"


Bingo, that seemed to be the issue. Shaved just a bit off, my ruler freely sides to the bottom of the gap behind the joint now, and there is no gap under the heel. :D


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PostPosted: Thu Jul 26, 2018 3:17 pm 
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Remember that when shimming the dovetail joint, it's far more important to have the heel fitting tightly at the bottom than at the top near the fingerboard. That's probably the reason that most of the literature omits the need to remove material from the end of dovetail there. We concentrate on having the tapered dovetail pulling in tightly so that the heel fits tightly. Some of us take it as self-evident that if the heel is to pull in appropriately against the body, there would necessarily need to be at least a small gap at the end of the dovetail down in there.

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PostPosted: Thu Jul 26, 2018 3:59 pm 
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Frank Ford wrote:
Remember that when shimming the dovetail joint, it's far more important to have the heel fitting tightly at the bottom than at the top near the fingerboard. That's probably the reason that most of the literature omits the need to remove material from the end of dovetail there. We concentrate on having the tapered dovetail pulling in tightly so that the heel fits tightly. Some of us take it as self-evident that if the heel is to pull in appropriately against the body, there would necessarily need to be at least a small gap at the end of the dovetail down in there.


That makes total sense Frank.

I really appreciate the lengths you have gone to on your website documenting different repairs and recognize that it would be impossible for anyone to cover every possible hiccup one may encounter when repairing old and abused instruments. Like in most things, I guess in luthiery common sense is worth quite a bit. ;)


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