Why is the first fret higher?
 

Seems on nearly all of my set up projects the first fret is higher. Even if there is no noticeable divots or grooves on the cowboy chords. Any ideas?

Shouldnt be

Steve

????

I've been playing for 55 years and I've never seen a guitar that had a higher first fret (with the exclusion of a zero fret).

I lot of them are higher when under tension, due to the torque on the neck from the strings bending over the nut. It is one argument for extending a rigid reinforcement past the nut into the peghead.
My setups almost always include cutting the first fret down, then lowering the nut to compensate. It can improve the feel significantly. The only practical way to check for this is under string tension. Simply supporting the neck under the nut and placing weights on the upper bout does not simulate this torque.

I have never noticed such a tendency in my own work, but then I DO extend neck reinforcement past the nut.

Gosh, I have never noticed this phenomenon either. And I DON'T extend the neck stiffeners into the headstock. I still don't really understand the physics behind that. Allow me to think out loud - I guess it's easy to think of the end points of string tension being the nut and the saddle but it's really each individual tuner and the bridge plate. So the forces imparted on the neck shaft from each tuner up to where it wraps around the nut is shoving the head stock into the end of the neck shaft?

Torque. The strings bend over the nut at a 15 degree angle, so there is a bending moment around the nut. Picture grabbing the end of the headstock and twisting it (upwards on the end).
My repair experience is primarily with old Martins, where the reinforcement ends about 5/8" before the nut.

John is perfectly correct ... and the phenomenon is easily demonstrated if you have a set of graduated pin gauges and a short accurate straightedge such as a fret rocker or similar.

Lay the straight edge to span the first two frets , with the end touching the nut, and, using the pin gauges, measure the distance from the fretboard surface to the underside of the straight edge in two places : right in front of the nut and right behind the first fret.

The gap at the nut will invariably be smaller than the gap at the first fret (if the guitar is sufficiently aged) . On a brand new guitar... not so much.

You can use feeler gauges for this but pin gauges give a more sensitive (and more accurate) reading.

Setup jigs that simulate string tension work vee the same process, we put a strap around the nut location and then wind pressure up on the tip of the headstock to create the flex and neck bend.

Whilst I agree flexing occurs in the neck at the nut location when tension is applied, i have never come across this phenomenon where it makes the first fret higher.

I am curious what the OP is using to identify the first fret being higher if they are seeing the issue consistently

If I fret level a guitar on my bench with strings off and then string it up and set my truss rod to make the neck dead straight, the first fret has not dipped or raised due to the rotational forces at play at the nut. If we set relief then of course the first fret with respect to a straight edge will be marginally higher than the rest but that is simply dialed in relief

Steve

For a normal relief setting, anything more than 0.001" higher than the second fret is too high. Very often, I see 0.003" or more. Lowering the nut by that much will improve the feel.

Thanks John for verifying you have experienced this. Sorry I didn't reply right away, I forgot I posted the question, oops. I use a typical straight edge for fret leveling. Happens on older 30-40 yo acoustic guitars. Johns explanation seems plausible, I'm surprised others haven't noticed this though. These guitars tend to be lower end, mostly laminate imports. My other thought too is that if the nut is high or the strings don't quite touch the first fret nearly as much as the second or third fret on chording it doesn't have as much down pressure on the frets. As John says once I lower that first fret during dressing, the nut usually needs adjusting which helps the overall string height set up. It just amazes me how many of these guitars are like that. Any more theories?