Brian's Guitar from Conception to Birth or How to Build a Guitar in 62 Easy Steps!
19 Cut the Fret Slots
Before you start sawing away on the fret slots, you want to be damn sure the saw is going to stay perfectly straight and perpendicular to the fretboard and that it won’t wander and cut where you don’t want it to cut. You’re going to be cutting many fret slots and you don’t want to get halfway through and screw one up. I built a jig to hold the fretboard solid and to enable me to saw perpendicularly without the saw wandering off. Now lay out your fret positions. You can easily find a fret distance chart on the internet for your chosen scale length. All of the charts will give you the location of each fret from the nut (not the distance between the frets). This is so that you don’t compound an error all the way down the fretboard. It also allows you to clamp a ruler next to your fretboard without having to move it. Now you just need to make some marks using a combination square and a knife which will give you a very thin, crisp, and precise line. Fill in the lines with chalk so you can see them better. Once all the frets are marked, don’t just start hacking away until you’ve run a few trial cuts. If you haven’t done this before, you’ll want to get a feel for the technique before you start messing up the real thing. I also made an ingenious template to gauge the depth of my cuts: a piece of cardstock with a line drawn on it (wow, high tech!). You can also simply draw the line on the side of your saw. I used my Japanese pull-saw which has the appropriate kerf width for the frets I’ll be using. Make a cut, check the depth, and tweak the cut until it’s the right depth.
Once you’ve built up a little confidence, you can start making some cuts on the real fretboard. Carefully line up your marks centering them on the saw kerf in your miter box. I also used a small block to fill the gap between my fretboard and my miter box so the fretboard is supported at both edges to avoid blowing out the side of the board with the saw. Saw with a smooth and steady rhythm. Don’t try to rush things as you don’t want to foul the board and have to start all over. Check your depth frequently. Repeat the procedure for all of your frets. Once you’ve made it through all the frets, clean the chalk off the board with some mineral spirits.