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Hi,

I'm working on this dreadnought with bolt-on/mortise and tenon joint and realized that the neck is not well aligned. If I set 2 straight edges on either side of it while it's assembled and measure from both straight edges inner side to the center line I get a difference 6.75 mm or 1/4 inch which seems a lot to me. I used the elevate mortise and tenon jig and I made sure the neck side of the body was dead flat and perpendicular to the center line. But something obviously went wrong in the process...

Now, the mortise and tenon fit is really nice and ideally I wouldn't want to mess around with it so I wonder if I can live with a misaligned neck or should I try to fix this and how? Thank you in advance for your ideas.

Every time you look at that guitar for the rest of your life, you’re going to see that (but hardly anyone else will). You do need to place the bridge so the strings are centered on the fingerboard. Unless that causes one of your bridge pin holes to go through a brace, it shouldn’t cause any but the visual problem. Analyze and figure out where you went wrong so you don’t do it the next time. My opinion is that you should be all right.

If you wanted to fix it, you could glue cheeks to the tenon and reshape it (and sand the heel to fit at the new angle). One of the mottos in my shop is “You could always make it worse.”

I agree with Bob. It shouldn't make any difference you could ever confirm (as long as you are still putting the Bridge and pin holes over the bridge plate and are happy with the bracing support under the bridge location. Trying to fix it now can lead you to chasing your tail. Aligning the neck to the centerline always takes some work (depending on your method). A small amount of offset at the heel will be exaggerated at the bridge. I floss my heels to get the angle and always have to be mindful of the centerline since a few strokes on one side can make a noticeable difference.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

I do mortice and tenon neck joints also and have to tweak the alignment every time. It could be because I use my table saw to cut both. I won’t do the math,but 1/4” off center at the bridge location means one side of the neck (cheek) is just a slight bit off. Not 1/4” and probably not 1/16”. Take a sanding block and reduce it until it is aligned. Sand, fit, sand, fit. I have a plexiglass centerline finder that makes this dead easy.

I actually measured the offset at the lower bout so it might be less dramatic than it sounds. A plexiglass centerline finder would be helpful indeed.

All of my necks require some adjustment to be centered. I do the same thing Glen does. I use one of these to check the center, works well.

https://www.luthiersuppliers.com/lsprod ... ine-finder

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Steve Smith
"Music is what feelings sound like"

That should be no problem to finetune then. The neck is about 2.25" wide where it joins the body, and body is about 20" long, so the amount you need to shave off one side of the heel to correct it is 0.25" x 2.25" / 20" = 0.027" (less than 1/32").

I have the same device as Steve. Works great. I always have to do a little tweak to line it up with the center of the end graft.

A few extra passes with the sandpaper floss one the proper side usually does it. Even after 94 guitars I still fiddle around with optimizing the neck angle and set for quite a while.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

With a bolt-on the tenon is mostly just a locator; it doesn't need to fit tightly. You can adjust the angle as needed and shim it to get things snug and centered once the shoulder of the tenon is fitted.

The only instances where a tapered heel neck might be expected to come off a neck jig and actually fit re: either centerline or angle is a dead-flat and dead square (in both axes) neck area on the body. Many guitar bodies will show some curvature through the neck mount to avoid the somewhat clumsy look of flats in that area, so we expect a shallower neck back-angle at initial fit-up with a taper heel neck than we intended using the 2D fit info developed with protractor or via most neck fitting jigs.

What tends to be forgotten is that it is unlikely that the curve of the body through the neck mounting area will be identical side to side or from top to back. This is often the case with cutaway bodies where significant asymmetry is less evident to the eye as the body is blocked to shape for binding, etc., but may be seen in full body instruments due to the normal tolerance stacks seen on both custom and factory-made instruments.

In short, that is why we have a fitting process in the workflow, whether new construction or repair.

A little louder for the folks in the back!


Sent from my iPhone using Tapatalk Pro

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Goodness... did I write that? I know I was thinking about it, but apparently the filter between my mind and fingers was disabled.

Your M&T fits really nice and tight and you really don't want to mess with- I get that! But, the goal is to get the centerline of the neck in-line with the centerline of the guitar. To do that, you need to mess with the tenon, it's pretty common. That centerline finder is incredibly useful, and I suggest you order one (since you've already bought the ELEVATE fixture, it wont be as painful on the wallet).

If the cheeks fit well, you will take down one of the cheeks, and take down the opposite side of the of the tenon, so the neck will move (yaw) in the mortise pocket, in the direction desired, aligning the centerlines. One of the cheeks remains UNTOUCHED and serves as a fulcrum.

You asked "how"? John Hall's YouTube video on adjusting the dovetail uses the aeronautical terms PITCH, ROLL, YAW and ALTITUDE to describe the neck "attitude" which was very helpful in describing and visualizing the spatial relationship of the neck to the body of the guitar.

To adjust the YAW, to line up the centerline, your tenon needs to be steered in the desired direction by removing small amounts of wood from one cheek and from the tenon. Wood is removed from one end of the tenon , and also removed from the rearward part of the opposite side of tenon. This is done slowly and carefully, back and forth from one tenon face to the other with ~ 120 grit sandpaper on a hard block or sanding stick. Again, one of the cheeks remains UNTOUCHED and serves as a fulcrum.


When the center lines match (and your cheeks are 100% in contact with the sides) your tenon will be aligned, but no longer tight in the mortise. To tighten the mortise, you add two thin shims to the tenon: one opposite to the side you removed wood from, and one on the side that moved away from the mortise as a result. You will have to finesse the fit of the shims by gingerly removing wood from them until you get the fit you desire. This will all be done
I drew a greatly exaggerated sketch to help visualize it- you may benefit from drawing, or modeling, your own. Note that you are removing wood on about 1/2 the entire height (top to bottom) of the tenon, not the whole tenon. Note that the shims will be covering about 1/2 of the target area of the tenon (top to bottom) and not the entire length.

The whole process can take under 60 minutes, after you have a feel for the process. Take light passes with the sandpaper! You could of course, do as other have pointed out, and offset the bridge to the centerline of the neck, but 1/4" is quite an excursion off the centerline. I shoot for a centerline alignment of 1/32" or better, and ALWAYS align the bridge to the centerline of the neck. The cheek to side interface is flossed before and after finish is applied for a perfect fit.

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Measure Twice,

Karl Borum

Thank you all so much for these ideas and explanations!