Bryan Kimsey's Acoustic Guitar Setup Tips and Ideas

I'm checking the action on this Martin D-16 with a stack of automotive feeler gauges. Measure the clearance between the string and 12th fret. In this photo, the gauge is tilted a litte- keep it parallel to the strings and feel for "slap" when pushing the string down. As soon as the string just barely, barely slaps down, I've got a measurement.

I like to setup acoustic guitars with .004"-.008" of neck relief, as measured by capoing the first fret, holding down the low E at the body, and measuring clearance at the 7th fret. I like the following measurements for 12th fret action:

E = .105, A = .100, D = .095, G = .090, B = .085, E = .080

A few thousandths one way or the other won't matter much, but the main thing I like to feel is a consistent decrease in action. Many guitars that I work on have a saddle that matches the fretboard radius and this results in a higher D/G action than the rest of the strings. Combined with the increased tension of the D string, this produces a very stiff feeling guitar. I've arrrived at my measurements by measuring a bunch of well-playing guitars, including those of numerous professional flatpickers.

At the nut, I like 1st fret clearances of: E = .022", A = .020", D = .018", G = .018", B = .018", E = .016"

Unlike the 12th fret action, a few thousandths at the nut IS noticeable. On some guitars, I might run .020" on the low E and .014" on the high E, but it just depends on how the neck feels, how the guitar responds, and things like that. In any case, a well-adjusted 1st fret action can make a BIG difference on the feel of the guitar, all the way up to about the 5th-7th fret (un-capoed, of course).

One trick I suggest is to put a capo at the 2nd fret and play the guitar. If the guitar buzzes, start shimming the saddle up until you get a buzz-free action with a capo on the 2nd fret. When it doesn't buzz under normal playing, measure the clearance of the strings at the true 3rd fret (this would be the first non-capo'ed fret). Suppose it's .012". Now put the capo on the 4th fret and do the same thing, measuring at the 5th fret. You'll most likely get something like .010"-.008". Extrapolating this back to the nut, you can estimate a 1st fret action of, say, .014". That's usually just a shade low and given that the nut will wear over time and that the string's length is longer and just a general fudge factor, I'll bump that up another .002" or so, and end up with .016". I measure each string instead of relying on too much extrapolation and guess-work. The purpose of this exercise is to show you just how low your 1st fret action really can go. Compare this to the .025" or so that many new factory guitars come with.

Lots of luthiers will adjust a nut by pressing the string to the 2nd fret and adjusting the nut to where it just kisses the 1st fret. That's where I start but then when I've got the 12th fret action right and everything else adjusted well, I still prefer to directly measure the actual height at the 1st fret.

Lowering a saddle:

When I setup a guitar's action, especially one that's getting shipped a long ways, I'll often err a little on the side of "too high". I do this because it's relatively easy for you to lower the height, but I sure hate putting shims under a too-low saddle, especially one made of good bone or fossil walrus ivory. If the saddle's too low and if the neck relief is on the low side, you can raise the action a little by loosening the truss rod, if it's an adjustable one. However, I don't like to rely on this and prefer to have it setup right to begin with. An easy way to lower the saddle a little is lay a sheet of sandpaper on a flat surface and press the saddle against a square object like this little ruler. Pass the saddle back and forth over the sandpaper, keeping it snug against the ruler. This ensures that the saddle bottom stays square and flat.

When you're dealing with the kind of precision I like to work with, a ruler ain't gonna cut it and a pair of dial calipers is best for measuring saddle heights. Lacking those, draw pencil lines on the saddle bottom, sand them off, draw another set, sand them off, and repeat. This way you can clearly see your progress and won't over sand. Check the saddle and action frequently as you go. Instead of putting all the strings on and measuring your action, try this: before messing with the saddle take all but the two E strings off. Measure the action of both using a stack of coins or picks as a feeler gauge (providing you don't have a real feeler gauge). Adjust the saddle and check it using just the two E strings again. The result won't be your actual action, but it will be a relative action since you measured it before starting.

Nuts!

Slotted Bridges

This is a slotted bridge. If you look closely, you can see that the high E string sits tangent to the pin hole, rather than actually in the hole. This means that the pin will take up the entire hole and thus keep the string from coming out. Newer Martin bridges come unslotted, relying on slots in the bridge pin for string clearance. Older Martins, even those up the mid-80's, have slotted bridges. Slots have a lot of advantages: the string sits firmer against the bridge plate- supported by 3 sides instead of just 1, there's a lot less stress against the bridge pins, and they seem to sound a bit better, too. In addition, it's possible to ramp the slots, like I've done on this D-16, so that the string creates a sharper break angle over the saddle. Look at the B-string in this photo: see how far away from the pin the bend in the string occurs? That's because the string is traveling down a ramp to the pin hole rather than waiting until it reaches the actual pin. Also, you know how on Martins the bass pins are closer to the saddle than the treble pins? By ramping, I can balance this distance out and it seems to bring the trebles up a little more, or at least create a more balanced sound.

If you don't ramp the slots, this modification is nearly invisible, and in fact, many owners of 70's Martins aren't even aware that the bridges are slotted. Try turning your pins so that the slots face the rear of the guitar instead of the fingerboard. Put a string in the hole and see if your pins will still fit. If they do, your bridge is slotted.