Martin DM neck bolts?

[Hector Trevino]

On the bench we have a Martin DM which has a low vibration (sound) seems to be in or about the neck if/ when you tap or bump it with heel of hand, (not when playing normally). Sounds like loose truss rod, but tightening or loosening has no effect on this loose sound. (All body bracing is solid) I also noticed that the heel is just barely pulling away from the body. I know that this model has a bolt in neck joint. I am thinking that a neck bolt may be loose. I think it is hidden behind a small wood Martin name plate at the "neck block" does anyone know how to remove this name plate to get to the neck bolt? I have tried using a heat pad to soften any glue but it did not budge. Am I on the right track? Any help is appreciated. Thanks

[Steve Beckwith]

Hector,
I glue my plates on with tite-bond and they should pop right off if you can get a blade under the edge. However, if the customer is the original owner (i.e. it's still under warranty) I wouldn't touch it without letting the owner know it could violate the warranty. If you do pop the lid and the tightening the bolt doesn't snug the heel up to the body, then it might be the insert the bolt screws into in the neck tenon is loose.

- Steve

[Greg Mirken]

I don't bother with heat to get those plates off; work an artist's palette knife under an edge and carefully pry. The foam tape will let go. Try tightening the bolt. If that doesn't do it the neck should be reinstalled. The guitar has gotten warm and dry enough that the neckblock shrunk, making the bolt loose, and the glue crept.

[Michael Burton]

Hey there:
I have a Martin DC-16RGTE which has a mortise & Tenon with bolt too. Its neck is also loose. So if I wanted to reglue the neck, do you remove that bolt, then free up the fretboard extension, and inject steam into the joint as in typical dovetail joints?

Cheers!
Mike

[Steve Beckwith]

No steam. Pop the cover on the head block and tighten the bolt.

[Mark A. Kane]

Mike,

To answer your question, you are correct in that steam will loosen the joint. First, loosen the fingerboard extension. If the fingerboard is black Richlite be very careful to not overheat it as it will bubble the top layer and there is no good fix for it. It's not the end of the world if it happens, but you can avoid it by judicious use of heat. I use a heat lamp. It takes about 4-5 minutes to get enough heat into it for removal. A flat, wide blade does the trick. As for steaming, the steam hole should be drilled about 3/8" off center which should clear the truss rod. Angle the drill slightly toward the center. Leave the bolt in to concentrate the steam in the joint. Remove it after a short time and work the neck out. I've come across many of these with poorly fitting joints. I typically glue thin shims to the sides of the tenon, then trim and sand until the fit is snug. Everything else is fairly straightforward. Have fun!

[Walter W Wright]

that wood plate is held on with thick double-sided foam tape. drip some naphtha down behind it to soften the adhesive, then pry it off with an offset screwdriver or something, not a big deal at all.

tighten the bolt, or if it's missing you can add one! some of these had the same neck joint but didn't use the bolt, instead just gluing the heel in. grab a 1/4-20 machine screw maybe 3/4" long and crank it in there, that heel should pull right in.

afterwards you just clean up the adhesive residue and re-apply some double-sided tape before slapping the coverplate back on.

[Steve Beckwith]

One thing I forgot to add - throw a lock washer on that bolt. It will keep it from coming loose again. Walter - great tip about dripping the naptha to loosen the foam glue on the cover plate!

[Mike Kolb]

Just now doing a neck reset on an older Martin B1 acoustic bass, with a mortise/tenon neck joint and the same 1/4"-20 bolt, so the timing was perfect to learn about the double-stick tape on the serial number plate, thanks!   

Good advice, Steve, about installing a lock washer on that bolt.  I'm sorta' surprised Martin never put one on in the first place but better late than never. 

BTW, when steaming the neck out, I don't think it took over a minute's-worth of steam before the neck popped loose.... a piece of cake for a change!

[Freddie Cisneros]

Another vote for palette knives. The I.D. plates are fixed to the neck block with a double sided foam tape. Replacement double sided foam tape can be found at most hardware stores. I cut all my palette knife handles down to about 3 inches or less.