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PostPosted: Wed Sep 08, 2021 3:35 pm 
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Koa
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So I've taken off some of the material on the base of the heel and gotten the pitch of the neck into the ballpark I'd like, but now I'm having a very strange time getting the fit to work.

When I slide the neck back into the pocket the treble side has a gap, while the bass side looks ready to be flossed.
Attachment:
treble 1.jpg

Attachment:
bass.jpg


If I lean into it a little simulating shims in the pocket the treble side gets closer, but then of course the bass side opens a little.
Attachment:
treble 2.jpg


I also find my center line is out, and heavy on the treble side. Which suggests some material needs to be taken off of the treble side of the neck heel to swing the neck back on center, but I've already got a gap there. And honestly, with where the fretboard extension sits it looks like it was always off center anyway.

Attachment:
center line.jpg


Looking back at my first treble side picture I see that the heel is "tighter" at the fret board, I guess if I take some of that off it would swing the neck back on center and hopefully close the gap between neck and body. But then I'll be shifting the fret board slightly towards the saddle too.

Last question, is it common to have to remove material from the back of the dovetail? There's is very little gap between the tenon and the pocket.


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These users thanked the author Conor_Searl for the post: DanKirkland (Wed Sep 08, 2021 10:00 pm)
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PostPosted: Wed Sep 08, 2021 10:00 pm 
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Koa
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To answer your questions and give some advice.

Yes it is very common to have to remove material from the top of the dovetail. especially if the new neck angle is significantly different than the original one.

What you could try in this situation is to shim up the lower portion of the dovetail tight enough to hold it in the new angle. Then pop it in flush and then string up the guitar with no glue. The dovetail is a mechanical joint and requires no glue to really work, glue is essentially a belt and suspenders for the neck.

When you have it strung to pitch you can get an idea of what the action will be like with the current neck angle. This is also a good way to test your fitting skills by leaving it strung to pitch for a day or 3 to see what it does or if it creeps. If it creeps then you need to get your fit tighter.

As for your cheeks being out of alignment, if you have it strung to tension in a dry fit then you can really see which side needs adjusting and where you need to remove more material.

All that said. Do a shimmed dry fit strung to tension and find out what you need to do next.



These users thanked the author DanKirkland for the post: Conor_Searl (Wed Sep 08, 2021 11:21 pm)
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PostPosted: Wed Sep 08, 2021 11:22 pm 
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Koa
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DanKirkland wrote:
To answer your questions and give some advice.

Yes it is very common to have to remove material from the top of the dovetail. especially if the new neck angle is significantly different than the original one.

What you could try in this situation is to shim up the lower portion of the dovetail tight enough to hold it in the new angle. Then pop it in flush and then string up the guitar with no glue. The dovetail is a mechanical joint and requires no glue to really work, glue is essentially a belt and suspenders for the neck.

When you have it strung to pitch you can get an idea of what the action will be like with the current neck angle. This is also a good way to test your fitting skills by leaving it strung to pitch for a day or 3 to see what it does or if it creeps. If it creeps then you need to get your fit tighter.

As for your cheeks being out of alignment, if you have it strung to tension in a dry fit then you can really see which side needs adjusting and where you need to remove more material.

All that said. Do a shimmed dry fit strung to tension and find out what you need to do next.


This is an encouraging and helpful response. I'm grateful. Thank you.


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PostPosted: Wed Sep 08, 2021 11:23 pm 
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Koa
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As a follow up question, because I'm curious. Is there a reason shims are often put only on one side, rather than both sides of the dovetail? That seems counter intuitive to me if keeping the neck centered is the goal. But I'm probably missing something.


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PostPosted: Thu Sep 09, 2021 10:06 am 
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You have to put the shims where they need to be to get everything centered and lined up right. In a perfect world, everything might be symmetrical. In a perfect world, you wouldn’t need shims.



These users thanked the author bobgramann for the post: Conor_Searl (Thu Sep 09, 2021 12:08 pm)
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PostPosted: Thu Sep 09, 2021 10:33 am 
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Koa
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Conor_Searl wrote:
As a follow up question, because I'm curious. Is there a reason shims are often put only on one side, rather than both sides of the dovetail? That seems counter intuitive to me if keeping the neck centered is the goal. But I'm probably missing something.


Like bob said, in a perfect world we would need no shims.

Typically a shim on one side of a dovetail indicates that the neck block was off center and it had to be corrected with a shim to push the dovetail over to make the projection be centered.

Ideally you want a shim on both sides of the dovetail. But sometimes we can't get what we want lol

For example. I had a mid 70s D18 that had a neck that was horribly off center from the factory, the shim on the bass side was maybe .90 thick and the other was barely .20 thick. With the two in there the neck was centered up right where it should be, but had I kept them even the alignment would've been off. At the end of the day you do what's needed to make the instrument work and function correctly.



These users thanked the author DanKirkland for the post: Conor_Searl (Thu Sep 09, 2021 12:08 pm)
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PostPosted: Thu Sep 09, 2021 10:38 am 
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Quote:
At the end of the day you do what's needed to make the instrument work and function correctly.


^^^ THIS! ^^^

We can offer general rules, but nothing is set in stone.
Listen to the instrument.

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PostPosted: Thu Sep 09, 2021 12:54 pm 
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Koa
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If I could get a little more perspective. I shimmed the neck and strung it up to pitch to see where the neck set is at. I guess it still does need to go a long ways.

My action is about 7/64" on the low E and 5/64" on the high e with less than 1/32" of saddle. The bridge is not an original bridge, and kind of a unique shape, it slants back quite a bit, (which makes me wonder how reliable the straightedge trick is when checking the neck angle.) The front of the bridge is a little more than 11/32" tall. My straightedge falls 9/32" below the bridge. So all in the neck angle lands about 3/32" shy of the bottom of the string.

Attachment:
bridge.jpg


I've already taken about 5/64" off the bottom of the heel. If I put my current numbers into the formula Dan Erlewine siggests in his neck reset video, I still need to take 3/32" off of the heel. That seems like a lot. Is that a lot?


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PostPosted: Thu Sep 09, 2021 1:34 pm 
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Cocobolo
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3/32” is a lot. Please recheck your work. I’m still thinking that your dovetail end is hitting the heel block. Close all of your gaps and then remeasure.


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PostPosted: Thu Sep 09, 2021 1:58 pm 
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Koa
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Do what bob said first and then check your projection again with the strings on. 9/32 below the bridge is crazy low.

If the bottom half of your dovetail is not fit well then you'll get a slipped heel style projection which is not good. Bear in mind that I have had some necks that were so severely out that it required more than 1/8 to be removed from the heel but that is few and far between and typically not on 60s Gibson made items.


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PostPosted: Thu Sep 09, 2021 2:02 pm 
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Another thing you should check. Look at the binding around the fingerboard extension. Is it straight going under the fingerboard or does it curve inwards towards the soundhole a little?


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PostPosted: Thu Sep 09, 2021 2:16 pm 
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Koa
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Oops...

The straightedge falls 5/32" below the bridge not 9/32" :oops:

Using Dan Erlewines formula...
A= the amount underset (5/32 or .156)
B= length of heel to bottom of FB (3 7/8" or 3.875")
C= from neck body joint to center of bridge (11 1/2" or 11.5")

.156 x 3.875 / 11.5 = .0526 more like 3/64" :oops: :oops:


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PostPosted: Thu Sep 09, 2021 2:40 pm 
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The 'straightedge trick' works well until variables in saddle height, depth of saddle slot. bridge thickness, and height of strings above the surface of the soundboard are accounted for.

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PostPosted: Thu Sep 09, 2021 5:20 pm 
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Conor_Searl wrote:
Oops...

The straightedge falls 5/32" below the bridge not 9/32" :oops:

Using Dan Erlewines formula...
A= the amount underset (5/32 or .156)
B= length of heel to bottom of FB (3 7/8" or 3.875")
C= from neck body joint to center of bridge (11 1/2" or 11.5")

.156 x 3.875 / 11.5 = .0526 more like 3/64" :oops: :oops:


Mistakes happen. I would suggest not getting too hung up on measurements. I've actually never measured how much to take off and I just use my eyes and a straight edge to get it where it needs to be.



These users thanked the author DanKirkland for the post: Conor_Searl (Thu Sep 09, 2021 6:50 pm)
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PostPosted: Thu Sep 09, 2021 5:34 pm 
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I haven't done a ton of resets so measurements and math are useful to give me a starting target on how much to remove and it keeps me from overshooting it, mostly.



These users thanked the author Barry Daniels for the post: Conor_Searl (Thu Sep 09, 2021 6:50 pm)
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PostPosted: Thu Sep 09, 2021 6:55 pm 
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Koa
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DanKirkland wrote:
Mistakes happen. I would suggest not getting too hung up on measurements. I've actually never measured how much to take off and I just use my eyes and a straight edge to get it where it needs to be.


I appreciate that. It's really hit home for me the simplicity of what's going on when resetting a neck, and not very different from shimming a telecasters neck. I guess in essence it is the same job. I had combined all the different parts into one thing, the relationship between the neck and shoulders of the guitar, and the dovetail itself, when really the neck set is only about the relationship between the neck heel and the shoulders, and what goes on in the pocket is simply the bolt that holds it all together once things are set properly.

The practical working out however is another thing...


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PostPosted: Thu Sep 09, 2021 8:32 pm 
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Dan, Since you don't use measurements, how do you go about cutting the heel down? Do you take a bit off and then do a trial fit?

I like to set the neck up in a jig and cut the cheeks with a chisel to the measured depth from the formula.


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PostPosted: Fri Sep 10, 2021 1:23 am 
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Koa
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DanKirkland wrote:
For example. I had a mid 70s D18 that had a neck that was horribly off center from the factory, the shim on the bass side was maybe .90 thick and the other was barely .20 thick. With the two in there the neck was centered up right where it should be, but had I kept them even the alignment would've been off. At the end of the day you do what's needed to make the instrument work and function correctly.


Just thinking about this Dan, when we're talking about a neck being off center it's that the joint is rotating kind of like an elbow, and the shims serve to push the rotation of that "elbow" back to straight, not that the neck is laying slightly beside the center line, and needs shims to push it over to get back in line. I suspect the second would only be possible in the case of some sort of catastrophic mistake in the initial construction of the instrument. And that would require a person to take an equal amount of material from the side of the tenon opposite the shim to physically slide the neck sideways and back onto center.


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PostPosted: Fri Sep 10, 2021 9:07 am 
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Not a catastrophe but normal. Necks on factory guitars are seldom accurately centered, square, or inline with the body center. A neck reset is an opportunity to correct these issues.


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PostPosted: Fri Sep 10, 2021 11:33 am 
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Barry Daniels wrote:
Not a catastrophe but normal. Necks on factory guitars are seldom accurately centered, square, or inline with the body center. A neck reset is an opportunity to correct these issues.


So what you're saying is it could be either situation, both need correcting, and resetting the neck is the opportunity to do so.

If I tease this out a little further, the point that matters or the functional centerline is the center point between the 1st and 6th string, not necessarily a point derived from measuring the actual body. Correct?


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PostPosted: Fri Sep 10, 2021 12:28 pm 
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Barry Daniels wrote:
Dan, Since you don't use measurements, how do you go about cutting the heel down? Do you take a bit off and then do a trial fit?

I like to set the neck up in a jig and cut the cheeks with a chisel to the measured depth from the formula.


More or less. I use a pillar file to start the cut with a few strokes on either side. I do this till I get close on either side, then I undercut the cheeks and then floss to where I want it. I usually start flossing when it's a hair or so away from being where I want it to be. I floss excessively according to some people but it does get me a really good clean line on the cheeks.


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PostPosted: Fri Sep 10, 2021 1:02 pm 
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Conor_Searl wrote:
So what you're saying is it could be either situation, both need correcting, and resetting the neck is the opportunity to do so.

If I tease this out a little further, the point that matters or the functional centerline is the center point between the 1st and 6th string, not necessarily a point derived from measuring the actual body. Correct?


Looking at it from a simplistic viewpoint: The body has a center line as well as the neck, and you want them to line up.

I determine the neck centerline with a homemade center jig but you can do the same thing by measuring the center point at the nut and at the 14th fret then connecting the two points with a straightedge. You can determine the centerline of the body several ways, like measuring the center point between the upper bouts and the lower bouts. Or you can use the center joint of the top, if you can find it.

The center jig makes it really easy. Set it on the neck, snug up the bolts, then look at the line that extends over the body. The goal is to get it to fall halfway between the 3rd and 4th bridge pin holes.



These users thanked the author Barry Daniels for the post: Conor_Searl (Fri Sep 10, 2021 3:02 pm)
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PostPosted: Fri Sep 10, 2021 3:16 pm 
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Make sure the bridge centerline is the same as the body. IMO what is most important for the guitar to play properly is that the strings are aligned properly on the neck and that means the neck centerline must be aligned with the center of bridge. I’ve done a few where the bridge was off to the side a bit.


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These users thanked the author SteveSmith for the post: Conor_Searl (Fri Sep 10, 2021 6:21 pm)
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PostPosted: Fri Sep 24, 2021 12:08 pm 
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Koa
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I'm getting much closer. Turns out at my last post, I was still actually a long ways away from a good angle. But I've really appreciated the advice to get the guitar to tension and see how it responds to the new angle. That's been a huge (albeit slightly tedious) help.

The treble side is fit nicely, with no real gaps, but there are two other gaps that I'd like to address. On the bass side I can fit a .0015" feeler guage between the heel and the shoulder, I'm assuming this should tidy up with some more flossing? The second gap, I'm not sure there's anything I can do about it. There's a .005" gap between the binding and the bottom of the heel, I'm assuming this is due to the fact that the binding has shrunk over the years, and is no longer flush with the wooden side. Is this something a person should just live with when resetting the neck of very old guitars where the heel originally sits flush with the back of the guitar?


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