Adjust the action at the nut. When the action is too high at the nut, the strings will pull sharp when you fret them. And, of course, the guitar is tough to play—we don’t want that.
As we know from the preliminary evaluation, the string height at the 1st fret was extremely high on this Jem. Usually, you can lower the locking nut by removing it and taking out small metal shims.
But when I took off the strings and removed the locking nut (Fig. 6), there weren’t any shims. This is one of those little “surprises” you’ll run into from time to time working on guitars.
Fig. 6: To remove the locking nut, take off the strings and then undo these two screws.
Instead of shims under the locking nut, I found a big glob of paint (Fig. 7). This raised the locking nut, so it had to be removed. When a locking nut is jacked up too high, the best way to deal with the problem is to measure the depth of the rosewood slab that’s under the locking nut to determine if you can remove any wood without compromising the structural integrity of the neck.
Caution! If the action at the locking nut is too high, consult a qualified luthier or guitar tech before attempting to sand the neck.
Fig. 7: The paint glob under the locking nut acted like a shim.
Fortunately, the slab was thick enough that I could safely remove both the paint and some rosewood to lower the locking nut. I sanded off the paint and then about 1/64" of wood (Fig. 8) and reinstalled the locking nut.
Fig. 8: Sanding off the paint and 1/64" of wood lowered the locking nut and improved the guitar’s playability and intonation.
After tuning the guitar to pitch, I again measured the action at the 1st fret. It had 1/64" clearance at the 1st string and 2/64" at the 6th string. This is perfect action for the string nut—just high enough to prevent open strings from rattling on the 1st fret, but low enough to keep the strings from pulling sharp when fretted.
Next, I adjusted the string retainer behind the locking nut (Fig. 9). Here, the goal is to lower the retainer just enough that the strings don’t change pitch when you tighten the string blocks (Fig. 10).
Fig. 9: Adjusting the string retainer.
Fig. 10: The string retainer should provide just enough downward tension that the strings don’t change pitch when you tighten the string blocks.
Adjust the intonation. Adjusting the intonation is the final step in setting up a guitar. I’ve covered this process in detail in “DIY: How to Set Up a Fender Stratocaster.” Here’s a summary: Intonating a guitar involves adjusting the length of each string so the instrument will play in tune. I use a strobe tuner for this. First, install new strings and tune the 12th-fret harmonic on each string to pitch. Then, fret each string at the 12th fret and compare it to the 12th-fret harmonic, which is the reference. If the fretted note is sharp, move the saddle away from the neck. If the fretted note is flat, move the saddle toward the neck.
Some tips: Remember to always retune after every adjustment. Also make sure you strike the string as you would when playing. In other words, if you normally strike the string lightly, then use the same technique when tuning and checking the intonation.
On this guitar, some of the strings fretted sharp and others flat—the variation was between 5 cents flat to 8 cents sharp (a cent is 100th of a half-step). No wonder this Jem wouldn’t play in tune. Most locking tremolo systems, including the Edge tremolo, require a hex key to loosen the bolt that holds the bridge saddle in place. After you move the saddle to the correct location, tighten the bolt, retune, and check the intonation for that string. Take your time—it’s important to get this right.