Fitting The Dovetail Neck Joint.

[Gilbert Fredrickson]

I am fitting a neck onto a guitar with a well rounded upper bout. I have done a test by shaping the mortise piece of test material with a curvature that matches the curve of the upper bout at the head block. I routed these test pieces with the LMI templates and bits after watching Robert O'Brian epic educational production on the neck jig. The tenon will fit very well when trimmed. In fact, I went right to the fingerboard mating service of the neck being proud of the top by mere 1/16th of an inch. I will try to leave more room next time. Be that as may, what I am trying to avoid now is a gap between the outside edge of the inside face of end grain cheeks and the sides of the guitar, as I begin to pare this joint. What do you suggest be done to insure this neck mates flawlessly to the body. Thank you. Yes, I am now the master of high speed rotary tools. Again, thank you.

[Chris Lounsbury]

I always make a flat on the body which is at least the width of the fingerboard at the neck/body junction. After the joint has been fitted you can ease the transition to the rounded shoulders, outside of where the heel meets the body.

I assume that you are planning a shaped heel that tapers to a heelcap which is narrower than the fingerboard. If you were using a rectangular heel shape then I suppose you could get away without the flat on the body using the following method. Leaving around 3mm around the perimeter of the heel to make contact with the body, relieve the inner portions of the heel - in fact this is done regardless of heel shape in order to make it easier to establish or refine the neck angle. Once this is done then you can place sandpaper between the heel and the body (grit against heel), pulling it out to the side and repeating. Done evenly on both treble and bass sides this will fit the heel to the body but you must check to be sure the centerline of the neck matches the centerline of the body (yaw).

If you are creating a tapered heel and you use the sandpaper technique (called 'flossing') without a flat on the body, then you will change the neck angle (pitch) as you shape the heel to fit the shoulders of the body.

[Gilbert Fredrickson]

It is the Ted Davis L-0 plan. I notice that the modern Gibson L-1 "Blues Tribute" has a nice flat spot in the upper bout where the neck attatches. I have used the "flossing" method and agree that it can take material from the fingerboard area and leave the heel proud. I've undercut the cheeks on the test piece tenon to fit the body but have not yet shaped the heel to a close to final shape. This seems to be working. I've been looking at neck reset articles and other guitar and uke construction blogs. So far, nothing that says "undercut the cheeks of the tenon and the dovetail will keep pulling them into the body, coward." The dovetail will keep pulling them into the body, right? I mean Lloyd and Orville somehow managed this without a great deal of fuss.

[Alan Carruth]

Put cellophane packing tape on the back side of the sandpaper. This makes it slide easier on the guitar side, and also helps keep it from tearing up.

[Michael Lewis]

To clarify, specific terms have specific meaning. You stated . . "undercut the cheeks of the tenon . .".

Undercut the cheeks of the heel (the surface of the heel that contacts the body), and make the tenon fit the mortise. I usually leave the outside edge of that surface about 3 - 5 mm wide for the actual contact surface and slightly undercut inside that to the root of the tenon.

[Mario Proulx]

I hate the look of bodies with a flat area at the heel, and it's not any harder to fit the neck on a nicely rounded body.

Sounds like you machined it well, though I'd like to see it be a bit more than 1/16" proud, but that should work. If it's not enough, you simply add shims. Floss it carefully to get the heel and body mated perfectly, then check the alignment and neck angle, and make adjustments as needed.

Here's a tip on 'flossing': use a much finer grit than you're thinking of using. 220, even 320, works well, and will be surprisingly quick. As mentioned, put some packing take on the back of the abrasive. Apply the tape before cutting-off slices so that the tape goes right to the edges. Use very little pressure on the heel when pulling the abrasive through; if it resists, you're holding the heel too tight and if it chatters, you're holding it too loose.

[Simon Magennis]

@Alan
@Mario

Great tip about the tape on the back of the sandpaper.... Thanks.

[Gilbert Fredrickson]

I've routed the mortise and tenon on the guitar and after some fitting I have a fingerboard surface 1/8" proud of the guitar top. The angle is good at 1-1/2 degrees. Everything seems to be pulling together as I shape the cheeks of the heel. The heel is cut to a rough 1/16" of it's final tapered shape. I undercut the cheeks a little then shave a little of the the dovetail and hope it all meets when the fingerboad surface become flush with the top and the cheeks meet the sides. I'm watching the Blues Creek/ John Hall "Dove-tail" video. Good so far. The side-to-side and the yaw is right on.

[Gary Gill]

I hate the look of bodies with a flat area at the heel, and it's not any harder to fit the neck on a nicely rounded body.

Sounds like you machined it well, though I'd like to see it be a bit more than 1/16" proud, but that should work. If it's not enough, you simply add shims. Floss it carefully to get the heel and body mated perfectly, then check the alignment and neck angle, and make adjustments as needed.

Here's a tip on 'flossing': use a much finer grit than you're thinking of using. 220, even 320, works well, and will be surprisingly quick. As mentioned, put some packing take on the back of the abrasive. Apply the tape before cutting-off slices so that the tape goes right to the edges. Use very little pressure on the heel when pulling the abrasive through; if it resists, you're holding the heel too tight and if it chatters, you're holding it too loose.

I appreciate the tip. I have fitted about 10 dovetail necks on my tenor ukulele builds. Always looking to improve my methods. Thanks

[Patrick Hanna]

Alan and Mario, thank you both for posting the packing tape trick. I am so glad I clicked into this thread and read it through.

[Gilbert Fredrickson]

Viola! I've now finished the second well fit dove-tail neck joint. Thanks all. For additional practice, I disassembled a dubious hand cut joint and used high speed shaping machinery to fashion a new, more confidence inspiring meeting place for neck and body. Thanks, again.

I must say, this making of guitars in two pieces may catch on.