Raising 12th fret, worth it?

[ProfChris]

I have also seen this this happen fairly often. The fret may have lifted slightly, and was not quite level in a one spot. The slight lift made the spot more pronounced where it wasn't noticed before.

Me too, though I'm only an amateur builder and occasionally fix instruments for friends. Wood moves with humidity, and not predictably.

BTW, I assumed the original poster planned to fix this himself, and that it was a cheap instrument. An expensive instrument deserves a professional repairer, and you ask them how to fix the problem, rather than tell them how you think they should fix it. Thus my comment about levelling from the 13th up to match the 12th. My theory was that this would avoid a first timer screwing up the first 12, and should make it playable, though not ideal, above that. Levelling them all is, of course, the proper fix unless just the one fret is high.

[Dale Ludewig]

All these thoughts, IMHO, are valid, But going back to OP, he said it was one string on each of two courses. While the 13th fret may be high, what Adrian said a while back, in that it's that specific, the strings that close to each other, one causing problems and the other isn't- I'd look at the depth of the slots in the saddle.

[pops1]

It would be so easy with a quick look, instead of playing a guessing game.

[HoGo]

It would be so easy with a quick look, instead of playing a guessing game.

Sure.
The previous post about one spot being higher was about one spot on one fret as OP's problems were mostly on one string of a pair only. When fret lifts then it will affect more than just one string of a pair.
All this assuming that original fretwork was done correctly with no frets hammered in with undue stress or bent/ damaged frets by heavy hammering.

[pops1]

Actually it was one string on the E and one on the A. The lift, high spot may be between the two strings which is why it is only showing on one each of the two pairs. As someone said it could be the saddle slots lower for these strings too. We are only shooing in the dark here.

[Jeff Mando]

Here is what I am hearing -- provided there is no high fret sticking up that you can see, (the solution being to tap it back down or if it doesn't stay down, glue and clamp it down,) otherwise, being a new build, I'm guessing it is something minor, in other words, I would say keep it simple.

First question, how often do you go above the 12th fret? My first "good" acoustic guitar 50+ years ago, bugged me that it would fret out above the 12th fret and buzz and this bothered me because it wasn't "perfect." Years, later I realized I never played above the 12th anyway (and, over the years, I realized much of "life" wasn't perfect, anyway!) OK, if you "need" it to play above the 12th, keep reading.....

I worked for a builder and when he was getting his new builds ready for a guitar show, the day before the show we tuned everything to pitch and then checked for buzzing. We spot checked (again, under tension) with a fret rocker and marked the spot where the buzz was with a Sharpie (NOT, the entire fret -- just where a certain string buzzed on a certain fret), then loosen the strings just in that spot and very, very gently file it, tune it up, check it, repeat, again GENTLY is the key word, repeat until there is no buzzing. AGAIN, don't file the ENTIRE fret just the spot on the fret that you marked. Doesn't take long on a new instrument that is basically unplayed. You may need to follow up with crowning, 500 grit sandpaper, steel wool -- but again, just in that spot. Don't overthink it, would be my advice.

Needless to say, if you don't understand the basic principles described here, I would have a professional do it.

Good luck!

[Don Dv]

As I was playing tag with my little problem today, I finally noticed something I had not seen before: the 13th fret is not visually taller, but it is visually fatter, that is, wider, slightly, on just one side, towards the E strings, where the problem tends to happen most often. If that means anything. Now I have a possible clue in which direction to take this.

[rcc56]

Sounds to me like the "fat" end of that fret was filed at some point and not re-crowned. It is a sign that the work was not done using precision techniques. I would not be surprised if that fret is loose or poorly seated at the end. Take it to a luthier who has a thorough understanding of precision fretting techniques.

[JeffLearman]

Most likely, if you raise the 12th fret, you'll just have moved the problem up one fret to the 11th. As mentioned above, you need to understand the precise nature of the problem before you can apply a solution.

The 13th fret might be too high. The 12th fret might be too low. More frets might be out of alignment for the low action you want. A previous fret job might have been a poor one. Or something else.

Any qualified luthier should be able to tell you very quickly what the issue is.

[Don Dv]

Would a guitar luthier be qualified to work on mandolin frets? I have a feeling it would be much easier to find a guitar expert than a mando expert.

[rcc56]

Yes. Frets behave the same no matter whether the instrument is a guitar, an electric bass, banjo, mandolin, or mountain dulcimer-- except that if you run into an instrument with bar frets or tied gut frets, you have to learn to manage their quirks.

Find a repair person with a very good local reputation for fret work.

[Greg Mirken]

I have a simple test to see if a fret is loose [in this case your 13th]; I take a 6" steel rule and tap the end on the frets. Tight frets make a clear "tink", any where a fret is loose in the board it will go "tunk". This can happen anywhere along a fret. Since you say this happens on only one E and one A string and not the other, I would also look at the string slots in the bridge. One may be just a bit lower than the other.
I see now your comment about the "fatter" 13th fret. That suggests it is loose and flexed up when the builder was leveling the frets.

[Don Dv]

Well, I only said the fret was a slightly wide on one side, no idea why the talk about loose frets, no sound distinctions with a small metal ruler, the frets seem firm enough.

When I said visibly, I only meant my untrained eyes could see it, not that it was huge or anything.
On the picture, the pen is between the 12 and 13th fret, on the E side, just to attempt to show what I see (quality is not great).

[pops1]

If the ruler doesn't rock on the 13th fret when rocking on the 12-14th then it is not high. It may be as suggested a lower slot on the saddle???? Hard to see anything substantial in the pic.

[rcc56]

I hope that sooner or later, the mandolin will go to a competent repair man, who will locate the high or low frets; level, crown, and polish them, and after an hour or so of work, the mandolin will go home playing the way it should.

The best case scenario is that one or two frets have high spots that need to be spot leveled and re-crowned, which will take maybe half an hour including loosening the strings and tuning it back up. The worst case scenario is that one or two frets were poorly seated, have had too much taken off the top, and will need to be replaced, which will take maybe an hour and a half on the outside.