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This Martin “Seams” a Little Off

11/4/2011 – This article was featured in the November 2011 FLGR Newsletter. Sign up for free by typing your email into the window to the left and pressing Go!

1.0 Martin Loose Back and Side Seam.JPG 1.1 Martin Loose Back and Side Seam.JPG
1. A Loose Seam is causing problems for this Martin D-3R’s playability. It’s thrown the neck angle off so the action is considerably higher than it should be. 2. The Neck Block has pretty much no gluing surface on the back of the guitar which is why the back and side seam has failed at this high-stress part of the guitar.
1.2 Martin Loose Back and Side Seam.JPG 1.3 Martin Loose Back and Side Seam glue with hide glue.JPG
3. Thinking Inside the Box. This is not a problem with the traditional line of Martin guitars that have mahogany neck blocks with plenty of gluing surface… Inside the guitar, the kerfed-lining is cracked clean through. 4. Hide Glue is my go to glue for this repair. It creates a strong glue joint that holds up pretty well under high stress and heat. I am working the glue into the open joint with a thin probe.
1.4 Martin Loose Back and Side Seam.JPG 1.5 Martin Loose Back and Side Seam.JPG
5. My Clamping Strategy is deceptively simple. I need to realign the seam and clamp the open joint closed. The guitar is resting on 2 work benches and straddling the jaw of my twin-screw end-vise. 6. The Headstock is resting on a self-adjusting neck- rest. The tail block is resting on the padded surface of different workbench.
1.6 Martin Loose Back and Side Seam.JPG 1.7 Martin Loose Back and Side Seam.JPG
7. The Large Bar-Clamp is drawing the neck downward toward the vise jaw which pulls the seem back into proper alignment. The two smaller quick-grips and caul are clamping the joint closed. 8. Inside and Out everything lined up perfectly. No gaps in the kerfed-lining or the binding on the back of the guitar.
1.8 Martin Loose Back and Side Seam.JPG 1.9 Martin Loose Back and Side Seam.JPG
9. Reinforcing the Seam by the neck block will deter this problem from reoccurring. I’ll make a couple of maple blocks that will glue to the neck block, side, kerfed lining and back. 10. Lots of Angles I first established the angle between the back and lining, now I’m fine- tuning the surface that will be glued to the side.
2.0 Martin Loose Back and Side Seam.JPG 2.1 Martin Loose Back and Side Seam.JPG
11. Ready For Gluing I oriented the grain of the maple blocks to imitate that of a standard neck block. This way the strong, long-grain glue-joints will be with the back and side of the guitar. 12. Hot Hide Glue will glue the blocks to the neck block, back, lining and sides.
2.2 Martin Loose Back and Side Seam.JPG
13. All Done The blocks are a little bigger than I would like but I made them as thin as I felt I could without making them susceptible to splitting in the event of the guitar taking a blow.