Martin body cracked along fingerboard, one side only

[thefishinmusician]

Patient is a newer Martin which has cracked on the body on the treble side...It's a bolt on, and I'm wondering if removing the neck may make it easier to work on..I can pull backwards on the neck, and it doesn't move..I saw a link Frank had that involved removing a brace, but after inspecting under the top, it looks like a lot of bracing would have to come out...Any ideas???

[Jim Bancroft]

Has the cracked piece moved toward the soundhole? If not, I doubt the neck block has shifted. I'd check for loose bracing. It's possible that it cracked from drying out. If the neck block hasn't shifted, I'd just get some moisture into the guitar to swell the crack shut(maybe it's already tight?) and reglue it, using hot hide glue or if the crack is really tight you can use superglue

Sorry, I just realized you have pictures. I looked at the first picture only. You have a shifted neck block. You need to remove the neck and reglue the neck block, back into the original position, glue all the loose bracing, and once everything is solid, reinstall the neck.

Jim

[thefishinmusician]

After thinking about this a bit...What advantage will I gain removing the neck??

[Jim Bancroft]

You need to remove the neck to get complete access to the neck block. You probably will have to make a jack that extends to the end block, to force the neck block to the original position, then glue it.
It not difficult to remove the neck, and it will make the job much easier and with better access.

Jim

[Charlie Hoffman]

Jim is right - the neck needs to come out. In my shop we place a heavy flat wood block along the ribs where the neck was and using some heavy clamps, force the neck block (and the top) back into position. Then reglue any loose braces and further reinforce the crack. This isn't all that difficult even tho it seems a "major" repair.

[Ron Frazier]

Charley
I also think the neck should come out and the clamping sounds the best.
I have a rip off martin look alike that is cracked in the same place. I was thinking
of a jack but I didn't want to push the tail block out..
Any good ideas?

Ron

[thefishinmusician]

Hi Charley...Good to hear a local chime in...I was thinking about a wood block across the shoulders and pulling it back into shape...Possibly drilling a small hole though the block, and using the guitar tuner trick as we use on a side crack....only a bit beefier, like a bass string...Thoughts?

[thefishinmusician]

Second thought....Too much pressure on a weaker spot as apposed to pushing it back with large cramp might be mo' betterer....Thanks fer heppin' me thimk!

[Jim Bancroft]

There are a few way I can think of to get the neck block back into position. I'm sure once you have the neck off, and you think about it, you will come up with a solution.
Repair work is more thinking than doing, you will come up with some ideas.

Jim

[David Houchens]

I recently worked on a DM Martin. The neck block on that one was tapered on the bottom and only contacted the back at the kerfed lining. I can't understand why they thought this (5/16x2-1/2) would be enough glue surface for the bottom of a neck block. This neck block had come loose at the bottom and pulled the sides out with it. The guitar was brought to me for a neck reset. Didn't need it. All it needed was to pull the block and sides back in and glue. Long story short, I was wondering if this lack of support on the bottom of the neck block might have lead to the top of the block moving. Seems like a poor design to me.

[Frank Ford]

Just to be contrary, I suggest you NOT remove the neck! This kind of repair is much easier with the neck in place, and used for leverage to get things back in register.

Read all about it:

http://www.frets.com/FRETSPages/Luthier/Technique/Guitar/Structural...

http://www.frets.com/FRETSPages/Luthier/Technique/Guitar/Structural...

[Len Biglin]

Dave I agree with your theory about 1/2 glued neck blocks , I recently had a Gibson jumbo about 2 years old and the neck had pulled way up , same tapered back on the neck block . I think its probly OK on the tail block, and they do that .Len

[David Houchens]

I guess it lets the back vibrate a little bit more, maybe. But with all the great sounding guitars out there with full neck blocks, it seems a huge loss of glue surface to get rid of a small amount of interference.
Didn't mean to lead this thread away from original question. Sorry!