Neck Joint Question

[Grommet]

Here are some photos of the conversion to a bolt on neck.
A plywood jig held the neck while a 3/8 brad point bit was used to drill the pilot hole for the two barrel nuts which are separated by a short length of dowel.

Two 9/32 holes were drilled, one for each of two SS 1/4-20 socket head bolts. After inserting the barrel nuts and making sure the bolts lined up, two short marking pins were made by turning down some short 1/4 -20 threaded rod. These were placed in the barrel nuts almost flush with face of the neck dovetail to mark the locations to drill the headblock.

I used the 60's vintage Port-a-Shop to drill into the 1 1/8" thick headblock. A 12" 3/16 hex key was used to thread the bolts from the enlarged endpin hole.

The last few pics show the hardware used and shots of the mandolin with the neck bolted on. No glue yet, it seems plenty strong without it, but I'd consider it if there's good cause.

Next comes the new fingerboard. Can't wait to get back to playing!

Scott

[Grommet]

After the trial fitting, went ahead and glued the sides of the mortise, the butt join between the neck and FB extension, and the join at the bottom of the heel/back seam. No glue on the broad faces of the mortise or tennon. I'm certain the glue wasn't needed for strength with the bolts, but I it may help with stability. The hardware for the bolt-on connection worked well. During the glue-up I only needed to use a clamp briefly to set the set the neck a hair lower into the mortise. while the bolts were tightened.

[Grommet]

Bumping this old post on the off chance Cameron might be able to use something like this on his project.
Scott

[jim simpson]

I purchased a flea market parlor guitar that has a loose neck join and a missing fret where one would drill and inject steam. I figured I would complete the job and restore it only to find it was attached by a sing old wood screw from the inside. It had the same shallow joint as the mandolin in this thread. I used two screws inserted into the neck heel. The screws had threads on the other end so I was able to bolt from the inside of the guitar. It worked out great.

[Grommet]

Sounds plenty strong Jim. When I did the Santa Rosa above I had seen the barrel nut thing detailed elsewhere so figured it was a good op to try it out. That one needed a fretboard too to replace a concave one. Got played for another 2-3 years after that but relegated to a closet lately.
Scott