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  #1  
Old 02-27-2023, 07:43 PM
PhilQ PhilQ is offline
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Default Neck Reset/Angle problem

Hi there,

I have a question I would greatly appreciate any input on.

I built a 000-sized guitar for a professional musician, and realized I had glued the bridge a tad off to one side. In removing it carefully as possible, I still damaged the top and decided to start over.

So I took the neck off, routed off the old top and made a new one that was just glued on today. I prepared the sides a bit differently this time (everything above the sound hole flat, 28 ft radius below).

I had to shim the dovetail on both sides. The bottom of the heel is pretty tight against the guitar now.

If I slide the neck in, and put a straight edge on top of the frets, the gap between its underside and the top of the bridge in its right location is about 1/4 inch, which seems pretty excessive.

Is there anything I can do to reduce the pitch of the neck to what is should be? Do I need to make a new neck with a different dovetail angle?

I'm having trouble juggling all the variables to figure out what to cut or sand back, if anything, to get the right angle and I'm afraid to make a mistake that I can't fix...

Any advice would be wonderful.

Thank you!!!
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  #2  
Old 02-28-2023, 06:35 AM
Skarsaune Skarsaune is offline
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No need to make a new neck.

You need to adjust the neck angle.

Since you already have the dovetail cut/adjusted for elevation, you're going to need to shim the dovetail, so it doesn't sit all the way down in the pocket. Then go through the process of setting angle/center/elevation again.

Very common process. It's how neck resets can be done.

A favorite reference is a set of videos John Hall from Blues Creek Guitars has on YouTube for setting a dovetail neck. Go have a look.
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  #3  
Old 02-28-2023, 07:37 AM
PhilQ PhilQ is offline
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Thank you. The dovetail isn't bottoming out yet. I guess I am trying to understand if I can just shim the dovetail and change the angle of the bottom of the heel or if I also need to modify the angle of the dovetail itself.
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Old 02-28-2023, 08:47 AM
Fathand Fathand is offline
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Quote:
Originally Posted by PhilQ View Post
Thank you. The dovetail isn't bottoming out yet. I guess I am trying to understand if I can just shim the dovetail and change the angle of the bottom of the heel or if I also need to modify the angle of the dovetail itself.
If I understand your description correctly, you currently have too much neck angle. You will need to remove more wood at the top of your heel ( near the fretboard) than the bottom to reduce that angle. Roughly a 1/16", maybe more by a ballpark calculation.

This should create a gap at the top of your dovetail to be shimmed to make it fit again.

Last edited by Fathand; 02-28-2023 at 08:55 AM.
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  #5  
Old 02-28-2023, 08:53 AM
redir redir is offline
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1/4in is quite a bit. IMO you may need to make a new neck for that or your body joint fret will be too far over the body. But it's at least worth a try I suppose.

The problem you have is you need to change the angle of the TOP of the heal leaving the bottom alone. This will tip the neck forward but move that body fret forward with it. You can do the math to figure out how much that is and if it will affect your bridge location so much that it pushes the bridge too far off the bridge plate or not.

You have to think in 3d when doing dove tails. When you think about it you are tipping the top portion forward so there will now be air space greatest at the top tapering to zero at the bottom, that will need to be shimmed. At 1/4in you may even need to take some wood off the back top of the tail itself too, just depends on how deep your pocket is.
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  #6  
Old 02-28-2023, 08:56 AM
PhilQ PhilQ is offline
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That is correct. Too much angle at the neck. I understand i need to remove more wood at the front of the underside of the heel, but im unsure what to do with the dovetail to accomodate that new angle.

You are saying I should look at just shimming the top of the dovetail?

Thanks!
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  #7  
Old 02-28-2023, 10:04 AM
John Arnold John Arnold is offline
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If the neck heel fits tightly to the body, additional shimming will not change the neck angle. You must trim on the heel. Any time the heel is trimmed, it will require adding wood to the dovetail.
That assumes the neck already fits flush with the top when clamped.
You stated that the neck is not fully seated yet.
I am not clear about your neck angle measurement. Did you account for the amount left to seat the neck? You need to subtract that amount from the straightedge measurement at the bridge. That will be the resultant angle when the neck is seated.
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Old 02-28-2023, 10:30 AM
PhilQ PhilQ is offline
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Quote:
Originally Posted by John Arnold View Post
If the neck heel fits tightly to the body, additional shimming will not change the neck angle. You must trim on the heel. Any time the heel is trimmed, it will require adding wood to the dovetail.
That assumes the neck already fits flush with the top when clamped.
You stated that the neck is not fully seated yet.
I am not clear about your neck angle measurement. Did you account for the amount left to seat the neck? You need to subtract that amount from the straightedge measurement at the bridge. That will be the resultant angle when the neck is seated.
Thank you for the questions, and I apologize if my descriptions are not clear enough. At this moment, the neck dovetail goes all the way in the mortise and the bottom of the heel is pretty tight against the body. If it weren't for the angle, everything would be perfect. And the bridge isn't glued on yet.

The measurement so far with the neck on like that is 1/4" between the bottom of the ruler placed over the frets and the top of the bridge.

So I understand I need to trim the front portion of the underside of the heel to allow the neck angle to decrease. But I am at a loss as to how to then make changes to the dovetail so that the heel remains tight to the body considering the dovetail itself hasn't changed. So obviously I need to shim it... but just a portion of it or the whole thing or...

I hope that is clearer...

Thank you so much for the input
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  #9  
Old 02-28-2023, 11:15 AM
RogerHaggstrom RogerHaggstrom is offline
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You need to remove wood on the heel wings under the fretboard to tilt the neck forward. Any gaps in the dove tail connection to the neck pocket have to be filled with shims.

The problem with this is that the 12th/14th body fret will be moved forward, and the open string length will be shorter, making the intonation go sharp. You can move the saddle back on the bridge the same distance as the body fret is moved towards the bridge to restore intonation. You can also add shims to the surface of the neck heel wings when you have found the right angle of the neck and move back the whole neck, restoring the open string length. Using black ebony for this will make it look like a nice decoration.

Sometimes doing a neck reset is like trying to cut one leg of a rocking chair and finally end up close to the floor after a lot of cutting...
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  #10  
Old 02-28-2023, 01:00 PM
John Arnold John Arnold is offline
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On new builds, I set the neck so that a straightedge on top of the frets is about 1/16" above the surface of the bridge.
In your case, that means trimming the top of the heel about 0.050".
The shims required after changing the neck angle should be tapered in thickness. Fitting can be accomplished using carbon paper or chalk. It is easier to work the shims prior to gluing. It also means if you trim too much on a shim, just toss it and grab another one.
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  #11  
Old 02-28-2023, 03:13 PM
redir redir is offline
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John did the math for you. It's not nearly as much as I thought it would be. .05 is about 1/16th in. But I'm reminded that it's always the case that a little bit goes a LONG way when resetting the angle. So you will be able to use the same neck. Hopefully your bridge is not glued on already so then you can set in the proper place for compensation and intonation.

You have stated that you understand that you need to remove most of the wood on the face of the heel just under the fretboard tapering down to zero at the heel cap. So what I would suggest is start there and observe everything, it will start to make sense what you have to do. You don't have to carve any wood off of the tail itself unless as I mentioned earlier you do not have enough space in the pocket for the new angle.

It's important to remember that when setting a neck angle you not only have the angle the neck makes with the top and sides (head block) of the guitar but also the 'yaw' angle which is left or right affecting the center line. So if your center line is good right now then take equal portions of wood off on each side of the heel.

As for shims I like to put them in place while gluing the neck in at the same time. Some people like to glue them to the tail itself and then carve them. It's a matter of choice.
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  #12  
Old 03-05-2023, 05:45 AM
PhilQ PhilQ is offline
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Thanks everyone for the help and advice. I've managed to change the angle and make the joint pretty clean. John was on the money, as usual, with the details. The 1/16" or so that was removed doesn't make a large enough difference with the bridge placement that it would risk being off of the bridge plate.

Now i need to shim the dovetail to make the joint tight again. Do you typically use chalk to highlight contact points during the fit?

Thank you!!
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  #13  
Old 03-06-2023, 08:57 PM
John Arnold John Arnold is offline
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I have done so many resets that I mostly do the fitting by feel. But if I am having problems, I will go back to my old standby, which is carbon paper.
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  #14  
Old 03-10-2023, 11:26 AM
PhilQ PhilQ is offline
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Quote:
Originally Posted by John Arnold View Post
I have done so many resets that I mostly do the fitting by feel. But if I am having problems, I will go back to my old standby, which is carbon paper.
Thanks John, great tip!
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