I have always had success gluing lost frets with thin cyano, although I can assure you that you’re not the only one who hasn’t had that experience.I've had a couple of frets fall off of a Fly. I reattached them using super glue, but they came loose again. Next I tried gorilla glue, and so far they are still intact. Is there a particular adhesive you would recommend if I have to do this again?
It’s demanding, but not too difficult, and is really a quick job, but it must be done Exactly right, and is certainly Not an easy thing for an amateur to do.
This is something you Mos Def’ wanna get right the first time.
The keys to success are cleanliness, precise positioning, and achieving the correct amount of “over - bend”.
If the fret came off because it got a smack from the edge of a cymbal, or something like that (seen it!) and is dinged or damaged, it can’t be re used.
If it just "fell off", and you still have it, it’s pretty straightforward…..
There are two tiny “v” grooves rolled in the otherwise flat bottom of the fret wire, designed to retain the OEM methacrylate adhesive.
Usually, the glue bond fails at the fret surface, and whatever is left of the adhesive stays stuck to the fingerboard.
The methacrylate adhesive we used is the same kind of goo that used to be used to hold the little stainless steel blocks to an auto windshield to mount the center rearview mirror.
As the adhesive manufacturer specified no less than .002” (.05mm) glue line thickness, we added a small amount of precisely sized glass beads to the adhesive to act as spacers, to assure that the adhesive wasn’t all squeezed out by the formidable clamping pressure needed to insure a perfect bond on all 24 frets.
So If the adhesive failed at the fret surface, and you’re reinstalling the original fret, normally you get some alignment help, as the glue residue stuck to the fingerboard helps to line up the fret correctly by ‘keying” the fret with the two tiny triangular ridges of adhesive and glass beads.
In this case, it’s preferred to clean the fretboard with a solvent wipe, and Not attempt to abrade the fingerboard landing surface.
When replacing the fret, the best fix is to wick in thin cyanoacrylate with the fret clamped exactly in place.
The essential trick is to carefully bend the fret so that there is a .008” - .012”, (.2 - .3 mm) gap in the center when it rests on the fingerboard.
The reason I’m calling it a trick is that the frets are very hard, and therefore tough to bend evenly. If you don’t do it just right, you can make a bump or a flat spot that will doom your attempt.
I like to set the fret end on a block of wood, and bend by hand. It will take a lot of force. Take your time and get it perfect.
It’s Crucial that the fret has a smooth curve without Any hint of a kink or flat spot.
If you’re gluing a new fret, it should be precisely trimmed to length, and whatever fret end filing / rounding should also be performed first, so you don't stress the bond by pushing on it with cutting tools after gluing, if possible..
Before gluing, the fret bottom needs to be freshly cleaned, ideally by sandblasting with very fine media, but, as this rig isn’t found in most shops, you can get it ready by scraping with a single edge razor blade, and scrubbing with acetone.
You will need to make a 1/2” (13mm) wide block of wood with a groove cut to fit the fret, and make it long enough so that it rests on the adjacent fret for stability, and shape it to allow access for swabbing to clean up the adhesive.
So your clamping arrangement should allow you to…..
1) check with a straightedge on both sides and verify the correct fret height, and
2) have easy access for a Q-tip swab with a little acetone on it to clean up the cyano mess.
When you’re happy with the fit of the fret, clamp it in place, and verify its' location and parallelism.
It’s crucial to check the height of the clamped fret carefully. You may need to scrape some of the original glue residue off if the fret is too high.
If it’s too low, you can use aforementioned glass beads, or, alternatively, fairy dust.
To check that the fret height is exactly correct, Gently clamp in the center with your little groovy wooden block and check that the gluey fret’s height is correct on both ends of the fret.
All you need is one wimpy clamp in the center, over the fret, just a little force will be needed to clamp out the little over - bend.
When you’re sure all is correct, wick in a little thin cyano, and immediately wipe the excess off the board with a swab and a bit of acetone.
I like the super thin stuff from Mercury. It’s super strong, and wicks convincingly.
See also Parker Guitars Fret Repair information