Thursday, July 16, 2009

Fretboard Binding

The cool thing about building a guitar is that there is always something to do while waiting for glue to dry or for a missing part to be mailed. So the other day I did some work on the fretboard.

First it had to be thicknessed, which is an misnomer because I'm actually thinning it. The blank comes about 5/16" thick and needs to come down to 1/4" or even 7/32". I know that 1/32" doesn't sound like much, but little things can make a difference in playability and hand fatigue.

So I used the jointer and then a sanding block to reduce the thickness. No pictures here, because, really, you don't have that much time, do you?

Ok, next is to cut the taper. The fretboard needs to be wider where it joins the body than at the nut. I already have a posterboard template with the exact scale length and taper, so it's just a matter of transfering this to the fretboard. First I cover the fretboard with masking tape so that the pencil lines will show up clearly, then I draw the centerline on the fretboard. Then I lay the template on the fretboard, lining up the centerlines, and trace the taper onto the masking tape.

I am going to use wood bindings on the fretboard. Not all guitars have bound fingerboards, but this allows the fret tangs (the part of the fret wire that is hammered into the slots) to show. It's not ugly, but a lot of makers like to hide these by melting black lacquer wax on the ends, or by binding the fretboard.

I don't mind the fret tangs showing, but I love the look of a bound fingerboard. It really dresses a guitar up, and I don't imagine not binding the fretboard unless the customer specifically asks for it to be unbound.

Because I want the width at the nut and at the saddle to remain the same, I have to reduce the width of the fretboard by the thickness of the binding material. I'm using rosewood binding, which next to the black of the ebony fretboard provides a subtle yet classy contrast. I'm also going to sandwich a thin strip of black/white purfling between the rosewood and the ebony. The black line of the purfling will go against the fretboard and disappear, leaving a very thin white line. It ought to look sweet.

I use calipers to measure the thickness of the binding and purfling. As you can see, it's .105" thick.I use the calipers to mark this distance in from each taper line and draw a new line. This is the width I am going to cut the fretboard.

I use the bandsaw to cut just outside of this line:

Then I use the jointer to bring it down to the line evenly down the length. Just a bit of sanding to remove the jointer marks, and it's ready for binding.

First I glue the purfling to the binding, then cut a small piece to go on the bottom of the fretboard.

I use masking tape to glue it to the fretboard.

After it dries I use a chisel to cut a mitre on one end:

I then take a long binding/purfling strip and, using a disk sander, mitre its end to fit. Because of the taper it's not a 45 degree mitre, so I have to use a lot of trial and error to get a close fit.

I spread glue on the strip and use a couple of pieces of masking tape to put it in place,

then spring clamps to get a nice, tight glue joint. The spring clamps tend to pull up on the binding, so I use a couple of clamps to hold everything tight to the workbench.

I only glue one binding at a time. I could tell you that my experience says that it's better to have a stable side opposite the glue side, but most people glue both bindings at once. The truth is that in the trial and error of mitering the binding I discovered that the binding was now too short. Luckily I ordered plenty of rosewood binding for just this kind of stupidity, but rather than wait for the purfling lamination to dry on the new piece, I decided to go ahead and glue the one binding and then do the lamination.

After the one side dried I repeat the mitering and gluing process on the other side. I took a picture but it pretty much looks like the one above, so use your imagination to see the other binding being glued.

And here's the result: a bound fretboard.

It still needs fret dots on the top and side, and then I'll sand a 16' radius on the top, but that's for later.

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