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A solid spline for a
Split Peghead
© Frank Ford, 2006; Photos by FF
This A-3 was made in about 1907 and it has survived in remarkably good condition. Early Gibson mandolin necks were laminated with a center strip of 1/8" thick dyed wood, which, unfortunately, decomposes as a result of the dyeing process.
With time, the black lamination achieves the structural integrity of a charcoal briquette. What looks like a simple regluing turns out to be a bit more nasty, as the black layer continues to crumble.The fingerboard and dovetail joint tend to keep the neck together, but the peghead is vulnerable to breaking open.
Later, Gibson switched to using a solid piece for the peghead, and running the black line as a shallow decorative inlay so this damage would not occur.
But that still leaves us with thousands of instruments with a structural "issue." If we simply reglue the lamination, chances are it will break free and surprise us later on. I think it's a good idea to add some rigid stiffening reinforcement so the peghead can't flex.
I started by adding some new glue to the separated area, and I clamped the peghead against a flat caul in the to align the halves, and from the sides to close the joint.
Once I got the peghead reglued, I simply screwed it to the front of my workbench. Here's yet another reason I like a very simple bench - I can beat it up without feeling guilty.
Setting up my bridge saddle slot routing mill, I plunged into the peghead with a long 3/16" milling cutter and routed a nice wide channel.
A few minutes of sawing and sanding yielded a nice cross-grain mahogany spline to fit my slot.
No need to clamp this one. It was a good slip fit and I slid it in with a generous amount of fresh hide glue.
After a bit of trimming and touchup, I was able to blend the finish by French polishing.
Now, the front and back show no sign of the old break, and the peghead is as solid as it can be.
The spline is visible at the end, of course, but it beats having an unstable peghead!

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