Cutting Fret Slots
After I radius the fretboard, it’s time to cut the fret slots. For me, this is a two-step process. First, I use my homemade miter box to accurately mark the location of each fret, then I go back over them a second time to cut each slot to the proper depth.
The miter box works with a pre-cut guide that I make for each scale length. For this build, I’m using my 25.5" guide. I have guides for a number of common scale lengths, but since I make them myself, I can make one for pretty much any scale length I need.
The fretboard attaches to the opposite side of the guide, and the slotted side is indexed through the miter box using a razor blade mounted to the bottom of the box. The blade sits directly under the cutting slot and gives me a positive reference for positioning each fret.
You might notice a little peek hole on the side of the box. It lets me see that the guide is actually seating against the razor blade for each cut. You can also feel the guide drop into the blade as you move from slot to slot. The peek hole is just an extra bit of confirmation.
Once all the fret locations are marked, I add the depth guide to my StewMac Japanese Fret Saw and set it for the proper depth. I measure that depth based on the fret wire I’ll be using, then make a few passes through each slot to bring them all to the correct depth.
Finally, I check every slot with a depth gauge.
And you don't need to buy a fancy fret slot depth gauge to do this. I make my own from a short piece of the actual fret wire I’m going to use. I cut a small notch in the tang about 1/4" from the end, then file the barbs off the smaller section. That gives me a simple, accurate depth gauge made specifically for that fret wire.
A little homemade tooling can go a long way in the guitar shop!
