Repairing A Broken Headstock Using Reinforcement Splines

One of the most common structural repairs we deal with in the shop is the case of the broken headstock. While guitars are generally pretty well designed to withstand the abuse we musicians tend to put them through, the headstock is their Achilles’ Heel. A couple of factors play into this: first, most Gibson guitars or Gibson inspired guitars are made with some variety of mahogany for the neck material, which is on the softer side of the hardwood spectrum. On top of that, these designs often have a carved angled headstock, leaving the end-grain of the wood exposed (some use a scarf joint instead of a carved headstock, which is stronger, but is still susceptible to breaking). Plus a lot of wood is cut away for the truss rod access, right at the weakest point of the neck. This all adds up to a perfect storm of structural vulnerability.

You may be asking yourself: “Why do they build guitars with angled headstocks and soft wood?” Tone is why. The angled headstock creates a better break-angle across the nut which allows the open string to ring free and clear of any unwanted string vibration behind the nut, and mahogany has a warm and rich resonate quality that people adore. We often say you can build a guitar to last, or you can build a guitar to sound good. You can’t always have both.

This Ibanez Artcore  came in with a nasty broken headstock. It took a bad fall and the headstock snapped completely off of the guitar at the scarf joint, and sheered off well into the headstock exposing the truss rod, the underside of the fingerboard, and the jagged, splintered end-grain of the mahogany neck. It’s a ugly break.

First, I have to re-align all the broken edges so the two pieces will fit back together without any gaps, then glue and clamp the neck using some Titebond II wood glue and purpose-designed clamping cauls.

It’s all in one piece again!

Some novice luthiers would stop here and string ‘er up, but the structural integrity of this neck is still very much in question, and we don’t take any chances. I designed and built a headstock splining fixture to install splines that will maximize the structural reinforcement around the break, which will ultimately result in a headstock that is stronger than it was when it left the factory.

With the neck perfectly centered in the fixture, I use our Festool plunge router to cut spline channels into the neck that extend from just beyond the edge of the scarf joint all the way past the break in the headstock.

Now it’s time to make the reinforcement splines. I use quarter-sawn African Sipo mahogany, which is denser and stronger than the neck material. It’s good stuff.

I use Titebond II to glue them in place.

Using a combination of rasps, files, carving knives, and sand paper I then carve and shape the splines flush with the neck.

The structural repair is complete. Now I’ll spray some lacquer finish on there so we can buff and polish it to the original factory shine.

Good as new! Actually, better than new. This guitar is ready to rock!

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