If you are like I am and a real fanatic about pursuing the best possible setups, I think you’ll really appreciate a Nut Slotting Gauge. Now….all my guitars have locking nuts, and that’s alright for this nifty tool. Let’s see why….
The ideal usage for the gauge is measure the string clearance at the first fret. Maybe “Nut Slotting Gauge” just sounds cooler than “First Fret Clearance Gauge”. haha! Just place the plunger over the preferred string at the first fret (for me and my locking nuts, that’s pretty much either E string). The other arches you see in the photo are for it to straddle the other strings – if you play bass, there is also one spaced to handle bass guitars. The face of the gauge is made to spin to adjust the setting to zero – there are also digital options out there. Once at zero, push down the string and get your reading. Then work your way across each string. Incidentally, methods of pushing down the string include literally pushing down the string on both sides of the base or pushing down the plunger from the top. I like holding down the string with my fingers. Decide what works best for you.
The readings are in .001″. That’s thousandths of an inch. Yeah, I have feeler gauges and I’ve done the eyeball method, but how accurate are those options when you can get it to the specificity of .001′? Wow! Plus….as I’ve been using this tool over the past several weeks, I’ve found instances of some that I ‘thought’ were solid being out of what I wanted for a preferred range.
What is the preferred range? Well, that’s up to you. I try to shoot for between .010-.020″. Generally speaking, .020″ is considered a medium range. Find what is best for you and adjust accordingly. Open nut can be adjusted with nut files and locking nuts can be adjusted by methods that include lowering the nut shelf of filing down the bottom/underside of the nut. Find what’s best for you. If you aren’t sure, definitely take it to a qualified repair shop.
It can also be used for checking string height up and down the neck, which can be handy if you have one guitar that plays like a dream and you want some reference points to apply to your other guitars.
“Why does someone need this?”, you ask. I can feel ya. Getting that most ideal string clearance at the first fret can play a part in your action going down the fret and an even bigger part in how well your intonation is applied when playing. Too low could contribute to string buzz. Too high and fretted notes can go sharp.
“Why all the measuring?”, you may also ask. I can feel ya on that, as well. I’ve been in guitar-making workshops and laid hands on different schools of thought. One being to go by feel. Another being to measure and measure and then measure again. I can think of at least 5 customers of a “feel” builder that experienced quality issues that would have totally been avoided by proper applications of measuring tools. I think this also applies to the ongoing maintenance of a guitar.