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Gibson J-50: Broken Headstock

11/5/2008

1.0 Gibson J 50 Broken Neck severed headstock.jpg 1.1 Gibson J 50 Broken Neck glue cracked headstock.jpg
1. A Severed Gibson Headstock. This headstock was broken completely off and reglued twice already. In order to insure that this doesn’t happen a third time I’ll glue the headstock back together then reinforce it with a back strap overlay, sub-faceplate wedge and a new, ebony face plate. 2. Regluing the Headstock. If I wasn’t going to be seriously reinforcing this headstock, I would use hide glue for this step of the repair. However, I’ll be laminating both the front and back of this headstock which is what will really hold this busted headstock together. I’ll glue those laminations with hide glue. Besides, severed headstocks sometimes want to slide around during clamping which isn’t a problem if you have the long open time of a yellow wood glue on your side.
1.2 Gibson J 50 Broken Neck clamp neck crack.jpg 1.3 Gibson J 50 Broken Neck prepare neck for backstrap.jpg
3. Clamping the Headstock. Three clamps and a simple caul on the face of the headstock is all it takes to clamp things up. 4. Cutting Away the Back of the Neck can be done in a number of ways. I find it’s quick and simple enough to do the rough work with a sharp chisel.
1.4 Gibson J 50 Broken Neck Backstrap Overlay plane headstock.jpg 1.5 Gibson J 50 Broken Neck Backstrap Overlay.jpg
5. Trimming the Back of the Headstock with a block plane leaves a nicely finished and flat surface for me to work with when I do the final preparations for gluing. I’m using the shop’s Lie-Nielsen #9 1/2 block plane because it excells at making fine and true cuts. In order to temporarily reinforce the headstock while I remove the mahogany from the back of the neck and headstock, I made a large oak wedge to match the 14 degrees or so angle of the peghead. I’ve simply rested the peghead on the wedge and clamped both the neck and wedge to the work bench to keep things from sliding around. 6. Ready for a Lamination. You can actually see the glue line of a previous repair (the break I glued up was a new one). The last break must have been pretty bad because the previous repair person used epoxy and reinforced the break with a small piece of carbon-fiber. It’s important to do this kind of work with hand-tools, at least the final steps of stock removal, as sanded surfaces are not ideal for a hide- glue joint.
1.6 Gibson J 50 Broken Neck Backstrap Overlay glue and clamp rear lamination.jpg 1.7 gibson j 50 broken headstock pare down lamination.jpg
7. Gluing the Rear Lamination. I used hide glue for this because it makes a very strong, heat-resistant bond. The rear lamination is a piece of Honduras mahogany that I bent to precisely match the back of the headstock with the bending iron. Hot hide glue has a very short open time so I heated up the rear lam- ination in the microwave and warmed the back of the headstock with a heat gun. Heating up the parts lengthens the open time which gives me a few extra seconds to clamp things up. 8. Trimming the Lamination with a sharp chisel.
1.8 gibson j 50 broken headstock file rear lamination.jpg 1.9 gibson j 50 broken headstock backstrap sanded.jpg
9. Filing the Rear Lamination Flush to the surrounding neck with a rat-tail file. Next I’ll sand the repaired area with 220 grit sandpaper to get rid of the file marks. I’m being careful to leave as much thickness as possible immediatly surrounding the repaired break. 10. A Rear Lamination will seriously reinforce this broken headstock.
2.0 gibson j 50 broken headstock gibson face plate.jpg 2.1 gibson j 50 broken headstock gibson pearl logo.jpg
11. The Face of the Headstock doesn’t actually have a faceplate. Gibson simply finished the front of the headstock black. Carving down the face of the headstock and gluing an ebony faceplate and mahogany wedge will complete the reinforcement of this damaged neck. 12. The Pearl Gibson Logo. I could cut a new pearl logo and inlay that into the new faceplate, however, that would add substantial cost to this already time consuming repair.
2.2 gibson j 50 broken headstock route logo.jpg 2.3 gibson j 50 broken headstock tooth plane ebony face plate.jpg
13. Transfering the Logo to the new faceplate is a more cost effective option than making a new one. 14. Fabricating an Ebony Faceplate. After cutting the ebony to the rough shape of the headstock with the band-saw the faceplate needs to be thicknessed. I like doing this with a toothed block plane followed by standard block plane.
2.4 gibson j 50 broken headstock ready for finish work.jpg 2.5 gibson j 50 broken headstock after.jpg
15. Ready for Finish Work. If you look closely, you can see the wedged shape mahogany lamination beneath the faceplate. This lami- nation is present because I want the maximum amount of reenforce- ment surrounding the break without lowering the nut seat or increasing the thickness of the headstock. Since creating an endgrain to endgrain glue joint would introduce a weak spot into the headstock, I feathered the wedge from a micro- scopic thickness at the nut to over 5/32″ thickness at the end of the headstock. This allows me to leave the wedge lamination at a thickness of 1/16″ over the repaired cracks without creating an endgrain glue joint at the nut. There can be no significant overall increase to the thickness of the headstock or it would both look a little goffy and prevent the proper tuning machine protrusion from the face of the headstock. 16. A Reinforced Headstock.
2.6 gibson j 50 broken headstock after faceplate.jpg
17. A New Faceplate , wedge and “backstrap overlay” have made this headstock stronger than the day this guitar left the factory. If you look really close, you can tell that I made the headstock ever so slightly thicker at the e string tuning machines (where the break came through the face of the headstock).