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Reinforcing A Broken Headstock

August 5th, 2011

SG Broken Peghead RepairA while back, I outlined a (slightly) unusual method of repairing the broken neck of a Gibson SG. I mentioned that guitar would make another appearance soon and here it is.

The guitar suffered a broken headstock while still in its case. A neck-break in the case was the final straw for the owner—who’s had more than one Gibson require a neck repair— and he wanted to consider options to help prevent it happening again. We talked over the pros and cons of the various solutions and eventually decided on a backstrap overlay.

This methodis sometimes used where the break is too nasty or offers insufficient glueing surface to guarantee a sound repair. A backstrap was not a necessity to repair this particular break (and, indeed, it entailed additional expense to carry out) but the owner wanted to do something that would go towards preventing a reoccurrence.

NewImageA backstrap overlay involves removing some wood from the rear of the headstock and some way past the broken section. A patch is cut from new wood and is bent to conform to the curve between headstock-angle and neck. Because the inlaid patch has been bent to shape, its grain has no run-out and remains strong.

I explained to the owner, and I will to you, that this offers no guarantees. However, this method of applying bent wood certainly strengthens a weak area of the guitar and it will be stronger than the original.

Backstrap peghead repairHeadstock repair backstrap overlay technique

The first thing that needs to be done is to repair the existing crack. I’ve discussed this in a previous post so I’m not going into any detail here. A repaired crack is necessary so that the section to accommodate the backstrap can be removed. My usual preference, when doing this, is to run the strap right to the end of the peghead as the inlaid wood is more discrete. In this case, doing so would have removed the serial number and ‘Made in USA’ stamp and I decided keeping these better served the future value of this guitar.

A 3mm section is removed from the back of the headstock. The Saf-T-Planer allows me to do this cleanly right up to the point the neck angle gets in the way. The remaining section along the neck is removed with hand tools.

Repair patch for broken headstockBending wood for broken guitar neck repair

A piece of mahogony is thicknessed to the appropriate size and cut out roughly to shape. Out comes the trusty bending-iron and I work the wood into a gentle bend to conform to the section I’ve cut in the neck.

Clamping backstrap overlay on broken peghead repairReinforcing weak neck on Gibson SG

Some inelegant, but effective, clamping and glueing and the backstrap is in place.

But it’s not pretty. The patched in piece does allow you to get a look at the bend clearly though. Because the grain in that patch (backstrap) runs—uninterrupted—from end to end it’s much stronger than the piece that was removed.

Neck repair on Gibson SGCompleted SG headstock repair

A little work with routers, drills, knives and sandpaper and the new piece looks a little more like a headstock should. Some touch-up work helps hide the evidence. A (relatively invasive) repair like this can never be completely invisible under a translucent finish but this is pretty discrete.

We’ve repaired and strengthened a broken-necked SG and preserved the serial number. Not a bad few day’s work.

Cross-posted to Guitarless

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Wood-Bending for Fun and Guitar Repair

June 27th, 2011

Acoustic Guitar RepairAn acoustic guitar with a dodgy, onboard preamp that had to be replaced.

What should have been a straightforward job became a little more complicated becauset the original preamp had a particularly large footprint. It was an older, discontinued model and the manufacturer was unable to supply a replacement that was as large. As it turned out, it was pretty difficult to find any manufacturer that had a unit that would cover the existing hole (and patching and recutting wasn’t favoured for cost reasons).

After quite a bit of internet rooting, a unit was found that would cover the hole in the guitar’s side. Great.

Just one problem though… Although the bezel covered the hole, the mounting screws were located such that the front two had nothing to screw into (see the locations marked on the blue masking tape).

Guitar Repair - Acoustic side patch
Guitar Repair - Bending wood for side patch

The solution: glue in some wood for the screws to mount in. As this is the shoulder of the guitar though, the wood patch needs to be bent, or curved, to mate properly with the guitar’s side.

No problem. Out comes the trusty bending iron. I cut a piece of mahogany a bit larger than needed for the final patch as tiny pieces are very difficult to bend. Even larger pieces need gloves as that iron gets hotter than the surface of the sun. Making sure to keep the mahogany damp, I gradually worked the wood until the heat and steam loosened the fibres—you can feel this happen. Then, working along its length, I bent the piece to the right curvature to match the guitar shoulder.

Instrument Repair - Acoustic guitar side fix
Instrument Repair - Acoustic guitar preamp

Once it was there, I clamped the bent wood in an acoustic mould (I picked a suitable position to mate with the bent wood) and waited for it to cool and dry. I could then cut it to shape and glue it in place.

The sides of an acoustic—and in particular, this area—play a very small part in its overall tone. This is why it’s possible to cut bloody, great holes for preamps in the first place. This patch is not going to have any effect on the guitar’s sound. It will, however, allow the new preamp to be mounted and will get this guitar gigging again.

Fix Acoustic Guitar Preamp