Archive for the 'luthiery' Category

Whiplash!

Wednesday, October 15th, 2008

Here’s a classic example of why I go to so much trouble to construct a scarfed, back strapped headstock. The owner of this Gibson Les Paul Standard wasn’t aware of having broken the neck - he opened the case and found it broken. Most likely, the case tipped or fell a short distance, and was stopped abruptly by hitting something. The weight of the tuners, supported at the end of the neck, combined with the Gibson Les Paul’s 1 piece neck (which results in very unfavourable grain orientation in the headstock area) and large trussrod adjustment cavity, allowed the whiplash effect to crack the headstock cleanly away from the neck.

From the side you can see that the only thing holding this all together is the plastic headplate, which is flexible enough to act like a hinge:

A (badly focused!) close up shows how little wood is left in the neck once the trussrod cavity is cut - you can see righ through the headstock!

The good news is; as easy as these breaks are to produce, they’re also pretty easy to fix. The headplate holds everything in alignment, and there is plenty of surface area for a good glue joint, which will be as strong as the headstock was originally.

To clamp the break closed, I use a spanish windlass setup. I run a piece of electrical cable (strong, with a cushioned surface, but not very stretchy) through the tuner holes in the head and around the lower strap button, then add tension by twisting a piece of scrap timber in the loop. Once it’s tight, I extend the scrap out to one side, where the neck prevents it untwisting.

This setup only works if the head veneer is intact, but is a very easy way of closing up the fine feather-edge of the break. It also allows easy access to all sides of the repair to clean up glue squeeze out. With the squeeze out wiped away with a damp cloth, I add an f-clamp (with a flat clamping caul and leather pad) to apply extra pressure of the rest of the break.

After for 24 hours, I unclamp the break, and carefully level the repair. Very little levelling is required, and the result afterwards is pretty clean.

However, it can be improved. Gibson still use nitro lacquer on their guitars, so this is what I use for touch up. I apply generous drops of laquer with the tip of a brush to fill any missing chips of finish, then sparingly brush over the entire area.

This lacquer needs time to cure, at least 1 week, or prefferably longer. Once it’s dry, it’s relevelled, wet sanded to 1200 grit and buffed to a shine.

Not a bad result if I do say so myself!

P.S: The guitar didn’t actually keep changing colour - that’s my photography and image editting!

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Thursday, August 21st, 2008

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Thursday, September 7th, 2006

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Wednesday, September 6th, 2006

Simplifying scarf joints…

Monday, September 4th, 2006

Sawdust generator

Tuesday, August 22nd, 2006

Conan the Librarian…

Friday, June 30th, 2006

What’s on the workbench?

Thursday, June 8th, 2006

Guitar of the month

Wednesday, June 7th, 2006

Classical Bridge Repair

Thursday, May 25th, 2006