Work On Your Bass

This vintage Fender Precision Bass has been a previous subject of my column [July ’05]. I replaced the broken trussrod and adjusted a huge amount of upbow (excessive relief) out of the neck. After setting the action, the bass played great—but soon afterward, the upbow crept back. There was still far too much relief for this vintage beauty to be playable.

I decided to refret the neck using a technique called “compression fretting,” the goal being to force the neck straight. It’s a complicated technique that should be performed only by experienced repair technicians—but I want to show it to you anyway, because if you know that a neck this bad was saved from the trash, you’ll be better prepared to weigh your options when your own bass needs work.

Compression fretting involves cleaning the fret slots without widening them, and then selecting fretwire as much for the shape of its tang as for the shape of its crown. (The tang is the “root” of a fret, which extends into the fingerboard and holds the fret in place with the help of diamond-shaped barbs; the crown is the part that touches the strings—the metal that sits above the fingerboard.) Fender fingerboards from this era are called round laminates: They’re extremely thin and glued to the neck on a curve. They have narrow, shallow fret slots, and the frets have narrow, short tangs. My goal was to straighten the neck by forcing frets with a taller, wider tang into the narrow slots. I had to deepen the fret slots in order for the frets to seat down against the fingerboard, but because I wanted to create as much compression as possible, I barely widened the slots at all.

Fig. 1 I clamped the neck into a heavy back-bow (with the trussrod loose) before heating the neck with an electric neck heater. When the temperature reached 450 degrees, I unplugged the heater and left the neck to cool. My intention was to soften the glue joint between the rosewood fingerboard and the maple neck, allowing the wood to set in the new position. Sometimes glue doesn’t melt and re-solidify, but even so, heated wood will bend and take on the new shape. When the neck had cooled, it had a noticeable back-bow—just what I had hoped for.

Fig. 2 Removing the frets is an important step, because it’s easy to chip the fret slots’ edges. I wanted the slots clean and tight. With a cotton swab I dabbed water along the sides of each fret; then I used a hot (80-watt) soldering iron to heat each fret just until the water started to steam. This softened the wood and the frets lifted out easily, with few noticeable chips. Where I did find some minor chips, I waited for the water to evaporate, and then I lightly spread some water-thin super glue over the chipped area. The glue hardened the chipped wood, and after it dried, I filed off the excess glue with a small, fine-toothed metal file.

Fig. 3 Using specialized fret tools, I scraped, sawed, and routed in order to deepen the slots in the middle portion of the fingerboard, cutting right into the maple. But to preserve the vintage look, I was careful not to cut into the rosewood at the fingerboard edge. I was also cautious not to widen the slots as I worked.

Fig. 4 The new fretwire had a tang height of slightly more than .073", compared to the vintage wire’s .055" height. That’s a considerable difference, and I hoped it would translate into a lot of fret compression. The original fret slots were just over .055" deep, and the new fret wire needed a depth of at least .075" in order for the frets to seat flush to the fingerboard surface. The pictures show the fret slot depth before (right) and after (left).

Fig. 5 The bass has a 7¼" fingerboard radius, typical of vintage Fenders. I used my vintage fret bender to bend the fretwire to that radius before cutting the frets to length. I cut the frets long enough to allow a slight overhang on each edge of the fingerboard; once the frets were in, I nipped off the overhangs and then beveled and shaped the ends for comfort.

Fig. 6 I notched the ends of each fret’s tang with a small file so that there were two different tang heights: (1) a shorter height to look normal at the frets’ edges, where the fret slots were shallower, and (2) the actual full height to hold the fret in.

Fig. 7 Here, I have deepened the slot into the maple for most of the fret’s length, leaving only the shallow-depth rosewood at the very edges for looks.

Fig. 8 I used a handheld fret press, loaded with a 7q"-radius caul, to force the frets into the slots in a controlled manner.

Fig. 9 I used another handheld fret press loaded with a flatter caul to be sure the middle of the fret was pressed home. (These tools use removable brass cauls that are available in radii from 7q" to 20".)

Fig. 10 When all of the frets were in, I was a happy fretter. Using a notched straightedge, I saw that I had close to zero relief. (The notched straightedge sits over the frets and reads the fingerboard independently from the actual fret tops.) Zero relief means the neck is perfectly straight, which was hard to come by with this lovely but stubborn Precision Bass.

The rest of the job was cake: I “kissed” the fret tops using a long leveler faced with 320-grit sandpaper, and then I rounded and shaped the frets and finessed the fret ends into the worn fingerboard edges.

I was thrilled with the outcome, and I’m glad that I can pass on the good news to Bass Player readers. Thanks for reading!