Saturday, June 20, 2009

Slotting the Fretboard

Saturday, June 20, 2009.

Well, happily, it appears I lied (well, how about "was mistaken"). I was able to get a little a little bit done on the fretboard after all. Not only was I able to cut it to the ebony shape, I was also able to order, receive, and use my Stew-Mac fret saw and miter-box as well. I also learned a couple of valuable things.

The first thing I learned was that it is easier to shape the neck to the fretboard than it is to shape the fretboard to the neck. I’ll explain - the fretboard, as a whole, consists of the ebony veneer (or whatever hardwood you end up using - I am using ebony), the binding, and finally the frets. In Siminoff’s book, he has you shape the neck and then, later, go build the fretboard assembly. This is fine, assuming you are careful enough right from the beginning to not allow yourself to cut the neck too close to its finished width. I did and, as I now know, I also went to far in a couple of places.

Another way thai I now know about, is to make the fretboard assembly first (since it is flat and thin it is much easier to control its dimensions) and then use it as your template for the final shaping of the neck. Why is this easier, you might ask? Well, for me anyway, having the fretboard done first gives me a real-world limit that, for some reason, is just psychologically better than a template - I know that the fretboard is what I will ACTUALLY be using and I cannot afford to make the neck narrower than it or I have to start over. With the template, however, I'm never quite sure where exactly to stop. It might be just me, but there it is.

So for this mandolin now, I am having to make the fretboard a bit narrow to match the neck, but since it’s mine and not for anyone else, this is something I can live with. It’s a learning thing, after all.

To get the proper shape then for the fretboard, I started by cutting the ebony blank to the shape of Siminoff’s template. This gave me the correct length and shape, especially for the base. I then held the initial cutout against the neck and traced its shape onto the back of the ebony and then, because I am going to bind this with some 0.06” thick plastic binding, I offset the traced line by about 0.05”. I then re-cut the ebony to its new, narrower dimension, ready for the binding. Once the binding is installed and the assembly is attached to the neck, I should have just enough overhang to allow me to scrape the binding to match the neck without making it look too thin.

All of this I did last Saturday and, before setting out for my business trip, I also ordered my fret saw and miter box from Stewart-MacDonald. When I returned on Friday evening, there on my desk sat my new saw and miter box, just begging to get used, so today I did. This is also where I learned my other lesson for the week - cut your fret slots BEFORE you cut your fretboard to shape. Why? Because the wood is still square (or at least you should be able to make it that way) and this is really helpful when using a miter box which is, by design, cutting the slots perpendicular to its sides. Because I had already cut my fretboard sides on an angle, I now had to find a way to line it up so that my slots were cut perpendicular to the centerline of the fretboard. Here is what I did.

In the first photo, you can see I have screwed the miter box down to my workbench. Fortunately, the designer of the box builds the thing with three counter-sunk holes so it can be screwed down without interfering with the work. I then placed a wedge shaped piece of wood inside the miter box to hold the centerline of my fretboard perpendicular to the cross-cut of the saw. This is actually one of the two scrap pieces from when I originally cut out the fretboard from the ebony blank. Once I had this located so that the slots at both ends could be cut, I glued it in place with Titebond. After the glue dried, I cut a slot in it with the fret saw. This served as my locating guide and is shown in the second photo.

The next set of photos show where I lined up and made my first cut.

When I was cutting the first couple of slots, I held the wood with my left hand while working the saw with my right. I figured I didn’t want to mess with having to clamp/unclamp for each of the 30 slots and the slots aren’t very deep...This, I found, is not the best way to do it. Not only was I pulling the wood away from the guide pretty regularly but my left hand got really tired, really quickly. Enough, I said. I used clamps for the rest of the slots - much easier to clamp and unclamp than to try to manually hold the wood with a fatigued hand.

In this shot you can see where I am using some wood cauls to hold the fretboard rather than just the clamps. I initially had to do this because of the design of my workbench and where I chose to screw down the miter box rather than because of the clamps or the work itself. Toward the end as I cut the last few slots, though, it became necessary anyway in order to clamp the work securely, so close to the saw blade. I think this shows up pretty well in the picture.

And here it is after all the slots were cut.

This picture shows that some of the slots are off by a very small amount one way or the other. I credit this to the fact that I cut the fretboard to shape before cutting the slots. Had I slotted it first with a square piece of wood, I feel confident the slots would have been more accurately located and probably more square. Once again though, I think this something I can live with. If it turns out to be enough of an issue once I am finished, I can always remove it (I will be using hide-glue to attach it to the neck) and build a new one to replace it.

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