The two most popular means of fret installation are the Hammer-In and Press-In methods. The technique of using a hammer to install frets requires years of experience and great skill, while the second option is somewhat amateurish, and requires nothing more than a specially designed arbor press, or a set of pliers called “Jaws”, and some hardened metal fixtures with radii to match the curvature of the fret board. When necessary, we also fit the instrument into a special jig to simulate string tension. Let’s take a look at the Hammer-In method of installing frets, and the tools involved in the process.
Tools & Techniques
Fretting Hammer: I started out using a shoe maker’s hammer to install frets because it had a rounded face which would not mar or dent the fret wire. I later modified a ball peen hammer by first rounding and smoothing out its face on a belt sander, then grinding and polishing its ball end down into a chisel point in order to create small gashes, or nicks in the bottom of Martin style bar fret wire. The sharp protruding edges of those nicks dug into the fret slots and kept the otherwise smooth sided fret material firmly in place. I still use the same hammer every day….just for installing frets.
Flush Cut End Nippers: I still make my own flush cut fret cutters by grinding down the face on a set of Crescent Brand End Nippers.
This tool allows fret wire to be cut neatly and precisely.
We’ve just learned about two primary tools of the Hammer-In method, and in a moment we’ll discuss elements of the process, but there are some things we need to understand first. In order for a guitar, bass, or any other fretted instrument to play well, the frets must all sit at the same relative height on the fret board, or be level and even with one and other. Otherwise, we’ll experience dead notes, string rattle, buzzing and other issues. Also, let’s not assume that we can just install some frets and play the instrument. Why ? Humans are not perfect machines. No matter how much concentration we apply to our work, It’s just about impossible for us to control the amount of force that we exert with a hammer, or even an arbor press each time we install a fret. Therefore, some of the frets are going to sit slightly higher, or lower than others on the fret board, and be uneven when checked with a straight edge. Another factor is that fret wire is an extruded medium. It is pulled through a series of forming dies under great force to render its final shape and size. All this pulling and stretching will naturally cause some discrepancy, or tolerance in the size of the finished wire along its length. It’s not uncommon to find a tolerance of .005” to .007” at the crown, within several feet of fret wire.
Leveling Instruments and tools
We now know that we can’t just put frets into a instrument’s neck, re-string it and play. The next logical step would be to make the frets level. You might want to review the August newsletter, which describes the process of leveling and dressing frets in detail.
Leveling and dressing newly installed frets is an exacting process which must be executed meticulously, and with great patience. The precision instruments and tools used in this procedure are leveling bars, radius blocks, special abrasive papers, flat, concave and triangular files, machinist straight edges, feeler gauges, back light and neck adjustment tools.
Leveling bars: Leveling bars are either dead flat, or machined to a specific radius. They are available in different lengths and widths, and are manufactured from a variety of materials, including aircraft aluminum, steel and hard wood. Radius Blocks are smaller than leveling bars, and are used a lot for small area, or “spot” leveling. They are also very useful as clamping cauls.
Abrasive Papers: The abrasives used in leveling and dressing frets come in two categories, Adhesive back for application to leveling bars and radius blocks, and the Wet-Dry type normally used for sanding auto finishes prior to buffing. The Wet-Dry paper is mostly used to burnish, and remove abrasive and file marks from frets after leveling and dressing.
Files: Files are primarily used to level frets (we sometimes go through entire boxes of new files in order to find two or three pieces that are dead flat when checked with a straight edge). Double “OO” Cut files with a plain, or “safe” edge, and are used for burnishing, de-burring, polishing, and the dressing of fret ends. Triangular Files are used to bevel and polish the edges of fret slots, to dress fret ends, and are sometimes used in place of concave fret rounding files, although they do not do as good a job. Concave Files are made in a variety of radii and widths, and are used to restore the round profile of frets after they have been leveled.
Straight Edges:There are several types and sizes of straight edges used in Lutherie, all of which are job specific. Standard machinist’s straight edges are used during the leveling process to identify frets that are either higher, or lower than others. Low frets will not touch the straight edge surface, while a high fret will cause the straight edge to rock back and forth across its crown. We continue to level the frets until they all make equal contact with the straight edge.
Back Light: This is an invaluable tool, and used along with the straight edge, it allows us to view even the smallest discrepancies in height from fret to fret. We can identify low frets quickly, as they won’t contact the straight edge and will allow light to pass through.
Feeler Gauges: Feeler gauges can be used to check the width and depth of fret slots, and are also used as an alternative to the back light to check for gaps between the straight edge and individual frets.
Fret Saw:The fret saw is used to cut and size the fret slots. A Dremel tool fitted with specialized router bits can be employed to prepare the fret slots on bound fret boards.
The fretboard must be leveled, and its proper radius restored. then the fret slots must be cut and sized to fit the fret wire of choice.
After all the frets have been installed and inspected for uniformity of fit, the instrument should be left for several hours to settle, or rest, as it has been subjected to stresses from the work performed. It is later returned to the bench for the following procedures:
• The neck is checked with a straight edge. The truss rod is adjusted to make the neck as straight as possible. A new nut is installed when necessary
• Protective tape is installed between each fret to protect the fret board from damage (ie) tool slippage, marring, scratches etc.,
• The frets are leveled, and their round profile restored. The fret ends are deburred and shaped using special files.
• The frets are burnished with various grades of sand paper, and either machine buffed with compounds and rouges, or hand polished with 0000 grade steel wool.
• The fret board is re conditioned and polished to remove any scratches, file marks etc. that may have penetrated the protective tape.
• A new nut is installed if necessary, and the instrument is completely cleaned, polished and set up.
The purpose of this technical article is to entertain and inform the reader. It should not be construed as an instruction manual or a tutorial. Any attempt to change the setting on a stringed instrument neck adjustment rod or “Truss Rod” can permanently damage the instrument. Improper adjustment of the truss rod can render the instrument unplayable, it can severely damage the neck AND the body joint in certain instances, break, or snap the truss rod, or even destroy an instrument neck. Master Luthier George Goumas, the Fretshop, and The Fretworks warn explicitly against attempts to make adjustments to an instrument’s neck adjustment rod by un-trained and/or inexperienced persons. I will not accept any responsibility for damages incurred to an instrument by anyone other than myself.