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On my first guitar. I'm using a mortis and tenon bolted neck joint. I wonder if I need to glue the portion of the finger board that extends over the body? Got a nice snug fit but I fear the fret install might curve it if not glued. Thanks for help. Jim M

If it's nice and snug just use a couple drops if white glue to keep it from buzzing.

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In my world view, the connection of the fingerboard extension to the top is part of the structural integrity of the guitar. It takes some shear load and rotational load from the neck and spreads it to the top and the upper transverse brace (which pretty much does nothing if you don't glue the fingerboard to the top).

If you don't glue it, you increase the likelihood that the heel will flex and allow the neck to pull up over time. You also increase the rotational load on the neck block and increase the odds of long term deformation of the box, the kind that leads to early neck resets.

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I bolt mine down with a 2nd mortice and tenon

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Andy Z.
http://www.lazydogguitars.com

I do it sort of like Andy's but I don't use a second mortise and tenon. Instead, I bury two T-nuts in the bottom of the fretboard and use two small bolts through small holes in the top. A thin plate of EIR reinforces the top where the bolts penetrate. It's working so far with three builds.

Pardon the partial hijack...
Barry, can you expand on how you get the t-nuts set in the FB?

I use a method modified from Charles Fox's designs. I route a flat-bottomed round hole in the bottom of the fretboard for the T-nut (I use two T-nuts). I also route a .060" deep depression (about 2" square) which will hold a reinforcing plate over the T-nuts preventing them from pulling out. The reinforcing plate is made up of three layers of woven graphite cloth and epoxy that is cast separately and then cut to shape. The T-nuts and plate are glued in place with some reinforced epoxy.

The two bolts go through the top of the guitar through small holes and are backed up by an EIR plate glued under the top between the UTB and headblock. The hardware is size 8 so it is fairly small and lightweight, but plenty strong for this application. The real advantage of this system is not having to cut a mortise in the top of the guitar.

I also use a little bit of glue, just enough to hold it in place. It does add some strength to the area. Also, I don't want any energy lost should the fretboard extension vibrate against the top. Every little bit counts.

Pat

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Todd,
do you scrape down to bare wood or glue to the finish?

I'm not Todd, but I scrape down to bare wood.

In my way of thinking about this. I only want the fretboard extension to be secure enough to keep from buzzing. If there is significant rotational force over time from the pull of the strings, I would really want that glue line to fail in shear rather than split the sound board along the fretboard edge like some of the old Martins do.

But then, it's probably better to construct a bod that resists those rotational forces better then a basic Martin style headblock.

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"There's really no wrong way, as long as the results are what's desired." Charles Fox

"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson