Friday, April 22, 2011

Jigs, Mortises, Blanks, and Tenons

Placing the box in the jig
Suddenly it seems things are moving along very quickly. A few weeks ago I had a bunch of pieces of wood that didn't resemble anything really, much less a guitar. Now I have a box that looks very much like a guitar and I'm ready to attach the binding and purfling, which makes the list of things left to do to the box pretty short. And I've already begun work on the neck. Don't get me wrong, I'm a very long way from the end (or even the light at the end of the tunnel), but tangible progress seems to be coming quickly these days, and that makes it a lot of fun.
This week I made good progress in two areas. First, I routed the neck mortise (that's the slot where the neck is inserted). Like many things about building a guitar, it's a very complicated and difficult task made much, much easier by a jig, which you can see in the picture at left. It consists mainly of a slot on the top that guides the router bit as you cut a huge hole in your guitar. (You may remember me describing that feeling last week. It was just as cringe-inducing this time).

The mortise after routing
The difficult part is positioning the jig, since placing it even a fraction off can cause huge problems, like a guitar that won't play in tune, buzzes a lot, and sounds horrible (all things one would like to avoid). But after getting it in just the right place, the rest is fairly easy. And after several passes with the router, getting deeper each time, you have a beautiful mortise ready to receive what you hope will be an equally beautiful neck tenon. But first one must have a neck. That was the next job.

In creating a neck, the first step is to create a neck blank, which is essentially a block of wood in the rough shape of a neck. It has a big chunk at one end from which the neck tenon will be carved, a shaft that will be contoured to just the right shape for the fingerboard, and a flat part at the end where the headstock will go. But first the wood for the blank has to be prepared. We're using mahogany - Honduran mahogany, to be exact - which is typical for guitar necks. And although the slab of wood was big and thick enough to make a whole slew of blanks, it's not just a matter of cutting it to shape.

Gluing the neck blank
Since it's so important for the neck to be not only strong, but straight and resistant to warping, the slab of wood is cut to the right length, then cut in half along it's length. Then it's folded together so that the grain of the wood meets in the middle, which will make it strong and stable after it's glued together (as you can see in the picture) and clamped. Next week, I'll cut the blank out of the glued piece and begin shaping my neck.

So we're moving right along now and I'm actually starting to try to estimate when I'll be able to finish. This is obviously a mistake, but it's hard to resist. And no doubt by talking about finishing, making lots of progress, and tangible results, I'm tempting fate in the worst way. But as strange as it sounds (especially for someone like me with a well-deserved reputation for impatience) I seem to be in less and less of a rush. Over the past month or two I've come to realize that I really enjoy what I'm doing. It's tedious sometimes and often frustrating, but all in all a very good way to spend a few hours every week.

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