In the debut episode of our new DON'T Do It Yourself? series, repair gurus from Gruhn Guitars in Nashville demonstrate an exceptionally delicate procedure on two classic axes.
We all know dead strings can compromise our tone, but so can fret wear.
While it might be easy for players to see, feel, and hear their guitar strings wearing out, it’s less obvious to see worn frets, despite their sharing equal responsibility for each note. Fret and string interaction is fundamental to the function of a guitar, but many players give little thought to the influence frets have on the way our guitars work, and how we play them.
Though the earliest frets were little more than pieces of string tied around a neck and slid into position by the player, guitar frets have been made from metal for centuries. For much of this time, a fret was a simple, straight-sided length of metal hammered into a groove sawn into the fretboard. This method worked well—particularly with relatively large-diameter gut strings—because the player’s fingertip was largely on top of the string and didn’t contact the abrupt, straight-sided fret much.
As smaller-diameter steel strings became increasingly common, the player’s fingertips contacted the sides of the fret more than before, creating a distinctly bumpy, ridged feeling on the neck. In response, wire makers created what we think of as a modern T-style fret, characterized by its larger semi-circular top section held in place by a slender straight portion, and, often, small teeth embossed in the sides to bite into the wood fretboard. This style of fret makes for a smoother playing feel and is easier to install at a uniform height. That’s thanks to the built-in stop that bumps into the fretboard’s surface when fully seated.
Regardless of the fret’s exact cross-section, the most critical aspect is that the top of each fret is exactly the same level as those in front and behind it. If not, the vibrating string is likely to contact the unwanted high spot and create a buzz or incorrect note. The frets don’t necessarily require identical height between the fretboard surface and the top of each fret—only that the tops of all frets fall in an even plane with each other. In fact, this is a typical scenario for a guitar.
The issue is that when two metal things rub together, they wear. Mostly, the harder metal will wear away the softer metal. Guitar strings and their differing alloys and construction styles have a wide variety of hardness, as do fret wires. Frets are bound to wear unevenly as we play, progressing to the point where an often-played note is measurably lower in elevation than a less-worn fret, preventing the string from playing accurately. The remedy is to grind the tops of all the frets into a uniform lower plane with respect to the intended radius of the fretboard, and then reshape the sides of each fret to a semicircular cross section to restore accurate pitch and consistent playability to every note. Since frets in the lower and middle portions of the fretboard are typically subjected to more wear than the highest notes, each successive fret-leveling operation tends to result in slightly shorter frets near the nut, and slightly taller ones at the dusty end of the fretboard.
After establishing a uniform plane across the tops of the frets, a second consideration is the overall height of the fret. The distance between the depressed string and the fretboard surface significantly changes the feel and playing style of a guitar neck. Put simply, smaller frets will tend to offer more accurate pitch for each note, while larger, taller frets can offer more expressive notes.
When a string is pressed to the fret, our fingertips subtly bend the string sharp as we push toward the fretboard surface. And as our fingertips contact the wood fretboard, the extra finger pressure is distributed, preventing the player from raising the pitch any further. This bending effect is minimized with small frets since they somewhat limit the player from pressing too much and raising notes higher than the intended pitch. In contrast, tall frets can exaggerate a deviation from the intended pitch, but they also allow for a myriad of expressive effects. This is because the player’s fingertips have a high degree of control to bend down toward the fretboard or sideways to alter the nuance of each note.
Regardless of the style or metal alloy, frets will wear over time. They can be leveled a number of times, but once they’re too low to play comfortably, it’s time to replace them to restore playability and expression to your guitar.
The fast-acting adhesive can work wonders ... if you know how to handle it safely.
Super glue plays an important role in many types of guitar repair. At our shop, we use it in dozens of ways, but unless you understand its properties and know how to handle it safely, you can wind up in trouble in a matter of seconds. Let’s spend some time exploring super glue and ways to use it effectively in common projects.
Some background.
Super glue is cyanoacrylate, a fast-acting adhesive commonly referred to as CA glue. You’ll find it marketed under various names—Super Glue, Krazy Glue, Gorilla Glue, Hot Stuff, etc.—and it’s widely used in manufacturing, woodworking, medical, dental, forensic, and automotive fields. Super glue is basically an acrylic resin that dries quickly.
Super glue is sold in various thicknesses that range from “water thin” to a thick gel. It’s important to choose the correct thickness for a given project. For example, thin and ultra-thin formulas flow into tiny spaces and dry instantly, which makes them useful for gluing in a string nut or seating loose frets—two applications we’ll examine in a moment.
A medium formula is great for repairing fretboard cracks. Because it’s thicker, it dries a little slower and this gives you a bit more time to work when you’re fixing split wood.
With the consistency of honey, the thick gel formula works as a gap filler. We also use it to repair chips in polyurethane or UV-cured finishes. Thick super glue can take up to five minutes to dry.
Typically super glue is clear, but Stewart-MacDonald also offers it in both black and transparent amber. We often use these colored super glues in the shop for touch-up projects.
Most super glue manufacturers also sell a spray accelerant that makes drying time nearly instantaneous. Photo 1 shows different types of super glue, as well as spray accelerant and applicator whip tips—small, flexible, hollow extensions that attach to the glue bottle’s nozzle.
Safety first.
When working on a guitar, super glue can be your best friend or worst enemy.
So before we go any further, let’s review the basic rules.
Always wear safety glasses when using super glue. Early in my career I learned the importance of eye protection: After splashing glue in my eyes, I had to dash to the emergency room. Don’t make that mistake.
Never touch your face when you have glue on your fingers. You can remove glue from your fingers using super glue solvent or fingernail polish remover.
Like water, super glue—especially the thin formulas—will accumulate at the lowest elevation, so always position the guitar to prevent the glue from moving away from where you apply it. For example, when touching up the finish on a guitar, make sure that area of the guitar is level. If it’s tilted, the glue will run to the lowest spot and create a mess.
Always have a cotton swab in your hand, ready to remove excess glue. But remember, you have to do this quickly or otherwise the swab can stick to the glue.
A clean applicator tip can make the difference between a job well done and a big mess. Applicator tips make it easy to apply the glue precisely where you want, instead of splashing it all over the guitar, and you can use them as they come or trim them down to whatever size you need. Suppliers like Stewart-MacDonald and All Parts sell applicator tips with their glues. Keep a pack or two on hand so you don’t run out in the middle of a project.
Finally, slow down and pay attention to what you’re gluing. Rushing through a super glue project is a recipe for disaster.
Okay, clear on the rules? Cool—we’re now ready to tackle two projects.
Securing a string nut.
This is one of the most common uses for super glue. Many manufacturers put glue on the bottom of the string nut before setting it in the slot, but I use a different technique. I apply a small amount of ultra-thin or thin formula to the “face” of the nut—the area where it meets the end of the fretboard.
Photo 2
Here’s why: When it’s time to replace the nut, you can more easily remove it and avoid damaging the slot. It’s a way to think ahead to make this project easier for the next tech that has to work on the guitar. If a nut has been glued in from the bottom, removing it can rip pieces of wood out of the slot. Use the 1st and 6th strings to hold down the nut and align it with the fretboard. Then apply one drop of ultra-thin or thin super glue to the face of the nut between the 3rd and 4th strings (Photo 2).
Photo 3
The glue will run along the nut and penetrate the small space between it and the edge of the fretboard. Use a cotton swab to clean up the excess (Photo 3).
Seating a fret.
Photo 4
Drastic changes in temperature and humidity can cause frets to become unseated in rosewood or ebony fretboards. When a fret pops up, I gently tap it down with a fretting hammer, and then seal it with ultra-thin super glue (Photo 4).
Photo 5
Quickly clean up the excess glue with a cotton swab (Photo 5).
And if that doesn’t do the trick, use a razor blade to gently scrape the dried glue off the fretboard (Photo 6).
You can use super glue for many other guitar repairs, so stay tuned for more projects in an upcoming column.
[Updated 1/25/22]