Measure the Action
1. Tune the guitar. Usually that’s standard E tuning, but as we’ve discussed, for this setup it was a whole-step below that.
2. Clamp a capo on top of—not behind—the 1st fret (Photo 1). This creates a “zero” fret and temporarily removes the nut from the action equation, allowing you to initially focus on neck relief (the amount of forward or backward bowing in the neck itself ) and bridge and saddle height.
3. Use a string action gauge (available from stewmac.com) or precision metal ruler to individually measure the string height at the 12th fret (Photo 2) for all six strings. The distance you’re measuring lies between the bottom of the string and top of the fret.
1. Before measuring action and neck relief, clamp a capo over the 1st fret. This temporarily removes the nut from the action equation. 2. Using a string action gauge to measure the action at the 12th fret.
On this Strat, the distance from the 1st string to the 12th fret was 6/64", and the 6th-string gap was also 6/64". This is very high action!
Measure Neck Relief
It’s important to determine if the neck has forward (concave) or backward (convex) bow. Along with saddle height, neck relief also affects the guitar’s action. Here’s the process:
1. With the capo still clamped on top of the 1st fret, hold down the 6th string at the last fret.
2. Using your action gauge or metal ruler, measure the greatest distance between the bottom of the 6th string and the top of the frets. The largest gap typically occurs somewhere between the 7th and 9th frets—essentially in the middle of the neck.
3. Measure the relief at the 1st string.
On this Strat, the relief was .022"—a little more than necessary.
Measure Action at the 1st Fret
Playability is also affected by how high the strings sit in their nut slots. The guitar feels stiff when the strings are too high. Conversely, if they sit too low, you’ll get a buzz when you play the open strings.
3. Measuring the distance between the bottom of the 1st string and the top of the 1st fret.
1. Remove the capo and measure the distance between the bottom of the 1st string and the top of the 1st fret (Photo 3).
2. Repeat the process for all six strings. When the guitar is set up properly, the gap should incrementally increase from the 1st to the 6th string to accommodate their progressively thicker gauges.
At the 1st fret, I measured a 2/64" gap between the fret and string, and for the 6th string, the gap was just over 2/64". Again, this is rather high, especially on the treble strings. Overall, this meant I needed to slightly tighten the truss rod (i.e., turn it clockwise) to reduce neck relief, lower the bridge saddles, and re-cut the slots in the string nut.
While taking these preliminary measurements, I noticed that the custom pickguard butted up against the tremolo base plate. This prevented the tremolo from moving smoothly when tipping forward to slacken the strings. When the trem arm was depressed, the base plate would get hung up on the pickguard—that’s what was causing the tuning issues the client was having with the trem! Before proceeding, I made a note that I’d have to trim the pickguard before completing the setup.
Armed with the information gathered in the previous steps, now we’re ready to begin the process of adjusting the action.