Preventing protruding fret ends

[Bob Gramann]

I build my instruments in a controlled and calibrated 42% relative humidity environment. For the guitars, this works well. Protruding frets signal that the instrument has been in a dry environment and the owner gets a lecture. The banjos present another problem. One store that has been very good to me displays its banjos near the front door of the shop. This won't hurt the banjos I make, but the frets end up sticking out after a couple of cold spells. Is there something I don't know yet that I can do to prevent this when I build? I don't like to do bound fretboards (because I don't like to play instruments with them and I only build what I like).

[Michael Lewis]

There are things you CAN do, like install shorter frets or dry the necks before you put frets in, but the practical answer is "no". Just file off the ends if they stick out. I would look at other instruments in the shop to see if other makers and factories have the same issue.

[Jason Rodgers]

When you say fret end, do you mean the crown and tang? I undercut the tang and fill the slot with CA and dust. If the board shrank, the crown ends would still stick out, but wouldn't catch and cut like the tangs.

[David King]

Michael is right, you can dry your necks to 20%RH before fretting but someone will inevitably dry them to 5% later so just give up and send out little fingernail files and polishers with instructions. It also gives a little work to thousands of under-employed luthiers around the world.

[Bob Gramann]

Pre-drying won't do it, either. Over several cycles, the frets will work to one side or the other (and, of course, not the same side all the way up the neck). I had thought of shorting the frets, but I want a neater job than that would provide in my hands. One of the reasons I don't do bound fretboards is that I don't like the free crown. I like the idea of providing a file with the instrument. In this case, I hid the store luthier to take care of it. I was just hoping that there was something I missed that would make this easier.

[Barry Daniels]

Are protruding fret ends inevitable? That has not been my experience with the instruments I have built. Could be the different climate. Also, my wood is very well cured.

[Bob Gramann]

I haven't had much trouble with the guitars (~100) I have built other than the ones that got dried out. All of those kept above 40% humidity had no problems. Also, I have been using Macassar ebony for most of my fingerboards for the past few years (including on the banjo in question). The wood on that banjo has been in my 42% shop for at least a couple of years. The Macassar ebony is pretty stable, much more so than the blacker African stuff. I have used Persimmon on a few instruments. That tends to be a bit more sensitive to humidity. This particular banjo was not kept in a humidity controlled environment. It is clear to me that the store it is in was drier than my shop. Our humidity fluctuates quite a bit with the seasons here. In the winter, a house without a humidifier can easily drop to 20% relative humidity.

[David King]

You might try African blackwood but even that will shrink at 20%RH. Agreed that Ebony is pretty hopeless. We should all start using Osage and be done with it.

[Bob Gramann]

I've only done a couple with Osage fingerboards so far. Those did fine, but I don't consider that enough data. When I can no longer get the Macassar ebony, I will probably use Osage. I think I may have lost a sale though because the prospective customer didn't think it was dark enough.

[Brian Evans]

I've dressed the fret ends on the birdseye maple fretboard of the guitar I finished in November three or four times. Getting a bit fed up with it.

[David King]

Birdseye is pretty but it's the least stable of the maples and maples are among the least stable domestic woods used in guitars. The fact that it needs to be flat sawn to look right tells much of the story. You can try acrylicized maple and see if that takes care of some of the shrinkage.