Work on Your Bass

In the guitar-repair game, unlike inbaseball, we allow four strikes instead of three, and strikes often produce home runs. I used about every trick in my playbook to win a game against this 1963 Fender Precision neck. Strikes one and two involved rethreading the trussrod [see July ’05], and later replacing the rod entirely. Then, last month’s column chronicled strike three, in which I refretted the neck using the “compression fretting” method—pressing thick-tanged frets into narrow fret slots in hopes that the wedging effect would force the neck straight for good. It worked great … for a while. Soon afterward, however, the neck crept back into an upbow—not nearly as bad as in the beginning, but enough to cause me to try one final repair. I decided to remove the last five inches of rosewood fingerboard (over the body), scrape the rise out of the maple neck below, and then replace the rosewood fingerboard.

The common term for the upper-register section of fingerboard over the body is the “tongue,” and this is where bolt-on necks often develop an upward rise, or “kink.” A kink creates a “rising tongue,” and with it comes buzzing on the last four or five frets, since the frets rise upward in that spot and get in the way of the vibrating strings. Kinks are caused, in part, by moisture absorption through the four neck-mounting screw holes, as well as through the hole for the trussrod-adjusting nut. Another cause is the fact that a bass neck is long, unsupported, flexible, and under the tension of string pull—except where the neck meets the body, where it is fastened with four large wood screws. If the wood feels like being ornery, the neck can’t help but kink in that area. (Not all bass necks are kinky.)

Last of all—and this is a major kink-maker—to adjust string height, bolt-on necks are often shimmed in the body’s neck cavity with a red fiber shim from the factory. Or, they’ve been shimmed at home with small slivers of wood, matches, a matchbook cover, a piece of a guitar pick, the tooth of a plastic comb, you name it. A shim lifts up the neck and leaves a void between the neck and the neck pocket. Meanwhile, the four mounting screws act like a clamp, pulling down on the neck heel and warping it over time.

In 1962, Fender laminated curved Brazilian rosewood fingerboards to maple neck surfaces that were curved as well. These are called “round-lam” necks. Fender’s earlier rosewood fingerboard necks, which used a flat glue joint, are known as “slab” boards. Separating a round-lam fingerboard from the maple is not easy because of the super-strong glue Fender used; heat won’t break down the glue as it will with most glues.

Fig. 1 Round-lam fingerboards are thin—much thinner than ordinary guitar fingerboards. When using replacement fretwire, I have to shorten the tangs to keep from installing the frets right through the fingerboard and into the maple. In the photo, the wire on the right is the original fretwire—quite a difference!

Fig. 2 I heated, pried, and chipped away the fingerboard, deciding early on to replace that section.

Fig. 3 I scraped away the remaining glue and rosewood, and I scraped deeper at the end of the fingerboard where the rising tongue was causing trouble.

Fig. 4 In this photo, you can clearly see that the surface of the maple rises closer to the notched straightedge. (The notches let the ruler sit over the frets, allowing me to read the fingerboard surface.)

Fig. 5 The maple is scraped and ready for new wood.

Fig. 6 While Fender round-lams are machined to a curve from a relatively thick piece of rosewood, I steam-bent my replacement piece instead (it’s easier). I used a sharp gouge chisel to make a pocket that would clear the metal trussrod nut.

Fig. 7 I attached the new section with Titebond glue and used a 7q" radius block as my caul.

Fig. 8 Once the glue had dried, I deepened the fret slots (which I had cut earlier, before gluing on the piece). I wanted them to almost touch the edge of the rosewood/maple glue joint, but not cut through it.

Fig. 9 I saved the original “clay dot” fret position markers and re-used them.

Fig. 10 All of this work was done with the bass neck clamped into my Erlewine Neck Jig, a tilting bench that recreates the string tension and actual playing position to eliminate needless removal of wood from the fingerboard. Here I am marking high spots to level out before fretting.

Fig. 11 One clay dot was too curled to use—it looked like a potato chip. I made a new one from tan PVC plumbing pipe, and I stained it dark to match the other.

Fig. 12 For side dots, a white pencil was perfect—the tapered pencil lead can fit any size hole snugly.

Fig. 13 I think I’ve avoided a fifth strike. Here you’re looking at the neck while it’s still bolted on to a “surrogate” bass body that I use when I work on frets. I bolt the neck onto the surrogate body, bolt that into the neck jig, and put the real body safely in its case.