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My frets usually start at .039" tall. What is the minimum height for the crown, before it is time to pull them and replace them. Usually, it seems the 14th 15th and 16th need the most filing to get the action dialed in, but sometimes they need pulling, to do some fret board planing.

About .020. Any lower, and it's too hard to radius the top of the fret.

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"Act your age, not your shoe size" - Prince

I agree with Chris as usual. I usually say about half the original height is all she wrote in terms of being able to recrown. This is the serviceability side of deciding if a fret dress or refret is in order.

I just refretted a 1995 Tele with maple board for a friend who is a professional, touring musician who opens for some of the biggest names in the business. His Tele frets measured 0.021" in the worst divots so I refretted it instead of dressing it out.

You can get lower on crowing with a three corner file but read the next comment as to why that was not prudent here.

My friend is a heavy hitter (and fantastic player) so very low frets although they would work would be a feel thing for him that he might not like.

Today although I think it's stupid.... there are people who want scalloped fret boards and jumbo frets making the trend over the last three decades for bigger and bigger frets and greater distance to the fret board. As such a guitar with frets only 0.020" high would feel pretty low.

many of my customers seems to be under .025 but by .020 they got to go. I am using jescars 40 80 wire for the most part

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Thanks. That fits with my experience on re-crowning

Geometrically speaking, the frets up the neck do not need to be as tall as those in the first position. Example: the distance between the 12th and 13th frets is exactly half the distance from the nut to the first fret. Therefore, the deflection required to achieve a given angle across the 13th fret is half that required at the first fret.

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John

If the frets were going to level out to at or below 0.025" we usually refret… as much for comfort as for the need to go to cant files or modified diamond files to avoid damaging the fretboard and binding during crowning. We did a lot of brand new Martin refrets with wire that finished to 0.045” until Nazareth went to the higher, albeit still rather low 0.042”.

On the fret geometry note mentioned:

- The argument assumes all strings are stopped at the midpoint between frets, which might be the case at middle positions, but is unlikely at lower positions and 'crowded' chord shapes (e.g., an A at second fret).

- In higher positions where - much like a mandolin or other shorter scale instruments - pressure is applied to both the stopping fret and the next fret away from the saddle, fretting force must include the greater applied force due to the need to bend the string over the next fret to achieve that stop. This applied force is often the limiting factor in player comfort, so will vary widely based on hand and finger strength, gauge of strings, and likely moon phase... it is a multi-variant problem even without how an individual player might choose to weight each variable present.

- There is also the matter of increasing string-to-fret-plane angle (with increase in fretting force) to the saddle, which admittedly is relief and overall instrument geometry dependent, as well as distance from nut and saddle for the target fret.

- Caution - potential for high school geometry class flashback. Avoid using that doubling of the angle with halving of the distance approximation at angles any greater than about 5 degrees. A protractor and some graph paper (or a trig function table in the back of an old textbook) will demonstrate the why of it. For very low angles, it works for the same reason that other small angle approximations work (e.g., trig functions with argument in radians: tan(x) = x, sin(x) = x; sinh(x) = x). As mentioned, for small angles it is a reasonable assumption for the sort of accuracy we need for setup.

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For the times they are a changin'

- Bob Dylan

How do you folks approach an instrument when frets are primarily worn in the first five frets and good otherwise? A fairly common presentation.

It always seemed kind of silly to me to grind down a bunch of good frets to level the bad ones.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

We do partial refrets especially if this is the case with something that has stainless on it. Full fret dress though be it partial or full replacement with all that that includes with us meaning relief where we want it, less relief where we don't want it and fall away milled in. We have repeat customers who we do partials for so the second time is much easier for us since the fret plane shaping has already been done.

This is a common occurrence by the way with cowboy chord players who never touch the other frets.