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Custom Guitar Truss Rod Replacement

Today’s Special: Truss Rod Surprise

Troubleshooting and Replacing a Custom Guitar’s Truss Rod

5/2010 – This article was featured in a previous FLGR Newsletter. Contact us if you would like to sign up for the free e-newsletter.

1.0 truss rod surprise.JPG 1.1 truss rod surprise worn out truss rod nut.JPG
1. A Custom Guitar made by an unknown builder. When this guitar came in for a refret I adjusted the truss rod. It didn’t adjust very smoothly and it wasn’t capable of getting the neck perfectly straight, but I figured I could work with the situation. While adjusting the truss rod before leveling the new frets the job took a turn for the worse. The truss rod gave up, letting the neck slip into an ungainly concavity. Before I can complete the fretwork, I need to get the truss rod working again. 2. The Truss Rod Nut is the part of the truss rod that you adjust to control the straightness of the neck. I’ve removed the nut and I can see that the threads look worn. Before I replace the truss rod nut I’ll clean up the threads on the truss rod.
1.3 truss rod surprise clean up truss rod threads.JPG 1.4 truss rod surprise replacement truss rod nut.JPG
3. Cleaning up the Threads on the rod is pretty straight-forward with this handy tool designed specifically for this task. 4. A New Truss Rod Nut. After tightening up the new nut the neck is still slipping into a back-bow. Looks like I’ll have to remove the fretboard in order to investigate the opposite end of the truss rod.
1.6 truss rod surprise remove fretboard.JPG 1.7 truss rod surprise fretboard removed.JPG
5. Removing the Fretboard with a thin knife is going easy. I’m using the shop’s heat lamp on the fretboard to soften the glue. 6. Locating the Truss Rod End with a stack of magnets is necessary since the end is not visible from the surface of the neck. If I’m lucky, this guitar will have a regular, single-action, single-rod truss rod. If this is the case, I’ll be able to drill through the rod and extract it through the headstock’s truss-rod nut access hole. This would allow me to replace the truss rod without routing away and replacing the spline that serves as a barrier between the truss rod and the fretboard .
1.9 truss rod surprise broken truss rod.JPG 2.0 truss rod surprise router jig for removing truss rod.JPG
7. The End of the Rod. I drilled through the graphite spline and the truss rod. Looks like I’m dealing with an “over and under” truss rod. There’s no way to remove this type of truss rod without routing through the spline. You can see where the lower rod broke on its own in the background and where I drilled through the upper rod in the foreground. Looks like the temper of the rod was compromised during the manufacturer’s bending process. 8. The Router Jig I put together for this project is pretty simple. It’s a piece of birch plywood with a 1/4″ slot routed down the center to accommodate the 1/4″ router bit. Carpet tape holds two plywood alignment blocks to the router’s base plate. Four screws will mount the jig to the neck.
2.1 truss rod surprise excavate truss rod.JPG 2.3 truss rod surprise old style truss rod.JPG
9. Routing is going pretty easy. I’ll make multiple, light passes until I can feel the router bit skid across the top rod along the length of the truss rod. 10. The Over and Under Truss Rod. This type of rod is made from a single, long rod that’s heated and folded back on itself. At the headstock end (pictured here), both ends of the single rod are attached to a metal cap that’s fixed to the upper rod and drilled through to allow the lower rod to adjust via the nut.
2.4 truss rod surprise broken truss rod.JPG 2.6 truss rod surprise drill out neck for truss rod anchor.JPG
11. The Bend End. This is where all of the rod’s troubles occurred. The temper of the rod at the bend was visibly damaged during the bending process. 12. Drilling the Anchor Nut Hole in the center of the neck at the body end will create a secure seat for the new truss rod’s fixed end. I’m installing a more traditional, single-action, single-rod truss rod. This is the same type of rod found on your typical Tele or Les Paul.
2.8 truss rod surprise thread truss rod.JPG 2.9 truss rod surprise peen rod to anchor.JPG
13. Threading the New Rod is quick and easy. The new truss rod must be threaded on both ends. 14. Securing the Anchor Nut. I threaded the anchor nut onto the rod, now I’ll peen it in place. This is the fixed end of the rod that will be secured in the body end of the neck. A punch and small hole through the bench-top are allowing me to make quick work of this step.
3.0 truss rod surprise wrap truss rod in shrink sleeve.JPG 3.1 truss rod surprise square filler stick stock.JPG
15. Heat Shrink on the new truss rod will eliminate the possibility of rattling after installation. 16. Milling the Spline. I flattened one face of this mahogany board with a jointer plane. Now I’m shooting one side flat and square.
3.2 truss rod surprise mark filler stick thickness with marking guage.JPG 3.3 truss rod surprise band saw filler stick to rough width.JPG
17. Laying Out the Spline thickness with a marking gauge. I’ve set the marking gauge to 5/32″. I’m pulling the marking gauge for more control. 18. Bandsawing the Spline to rough width. Next, I’ll use a #4 plane to smooth out the saw marks and bring the thickness down to the scribed line.
3.4 truss rod surprise plane filler stick to final thickness.JPG 3.8 truss rod surprise glue in filler strip.JPG
19. Fine Tuning the Fit of the spline. I’m using a block plane set for a very fine cut. The final steps of spline fabrication will involve drilling through the body end of the spline to create a good fit to the fixed anchor nut. Then I’ll cut the spline to length and taper the headstock end with a chisel so it fits under the headstock’s faceplate. 20. Gluing in the Spline. I’m gluing the spline with yellow glue and a platoon of bar clamps.
3.9 truss rod surprise chisel and scrape filler stick flush with neck.JPG 4.1 truss rod surprise prepare fretboard glue joint.JPG
21. Truing the Neck will create a nice glue joint for the fretboard. After planing away the majority of the spline, I’ve switched to a scraper both to remove the original glue and to trim the spline flush with the neck. 22. Planing the Fretboard with a #4 1/2 bench plane will create a good glue joint for the hot-hide glue I’ll be using to reglue the fretboard.
4.2 truss rod surprise reglue fretboard.JPG 4.3 truss rod surprise back together.JPG
23. Clamping the Fretboard to the neck is pretty easy and quick with the help of a huge rubber band and the army of quick clamps. The rubber band aligns the neck to the fretboard and the clamps prevent the rubber band from unraveling should it break. 24. A quick sanding with 600 grit sandpaper and a few coats of oil complete the truss rod replacement.
4.4 truss rod surprise new truss rod nut.JPG 4.5 truss rod surprise all done.JPG
25. The New Truss Rod Nut. 26. A New Truss Rod and new frets have this guitar up and running again.