Wednesday, July 4, 2012

Hello?....Hello?.......Is Anybody There?.....

Laying out the tone bars
I'm relieved to report that my absence from the blogosphere over the past three months didn't cause widespread depression or panic among my readers (hi again, Mom), although I'm sure there were a few tense moments along the way. And I'm ready once again to report on the lastest breathtaking developments in my guitar building adventure.

I didn't make a conscious effort to abandon posting to my blog but, after a while, I began to wonder why I didn't feel compelled to write anything and I eventually came to the conclusion that the reason I did take a hiatus says a lot about the process of building the instrument.

There are, of course, the practical reasons, like the fact that it's hard to find time to build a guitar when you can barely find the time to do all of the other things that come before it. The last three months have been very, very packed, so that certainly played a role. But in the end, I think the real reason for my delay had more to do with the challenges of building an arch top guitar than anything else.

I could probably spout out a very long and boring explanation right now, but I'll spare you the trouble of reading it and try to narrow it down to two issues:

I find the first reason most interesting. I think I mentioned several times how much I love the freedom of carving. It's one part of the process of building a guitar that doesn't require precise measurements and instead relies on feel and intuition to achieve the proper shape and proportion. But the fact is, a flat top guitar like the one I build before requires very little carving. Aside from the carving of the neck and the braces, there isn't much carving to be done. And the carving that is required is fairly focused. In other words, it's not that hard to visualize what a neck should look like and how it should feel.

Carving the back
An arch top, on the other hand, involves very little other than carving. And therein lies the problem: The very thing that makes it exciting - the freedom from structure - is also the thing that makes it difficult. There's the old saying that to make a duck decoy, "you take a chunk of wood and cut away everything that doesn't look like a duck." Well, that's easy when you're carving a duck. But what does an arch top look like? How thick is it? How much arch is there in the top? And I can tell you that when you're carving for two months straight, you have plenty of time to yearn for guidance.

The second reason is much simpler: Let's put it this way: Growing grass is an amazing process. The fact that a blade of grass emerges from the earth and soaks up sun and water and nutrients from the soil to grow into its beautiful, green self is fascinating. But I don't much care to sit around watching it happen. Same goes with arch top building. Building a flat top involves lots of different steps. Carve here, glue there, mitre here, brace there. Arch tops, on the other hand, are carve, carve, carve, carve, carve, at least to the point we've reached now. So there's only so much you can say about it and, as committed as I am to boring you with the minutiae of guitar building, I'm not a sadist.

With that long-winded explanation I'll move on to actually catching up on the progress, which has been substantial in recent weeks.

Measuring the thickness of the top
I've already written about the carving but, since a good part of that process is behind me, I'll write just a bit more: It's a long, long, process and, as I said before, the tough part is getting a feel for the shape, the amount of arch, and the thickness of the top and back. There are a few guides that can be used, but there are no specific measurements or hard and fast rules. Both the inside and outside are carved, though, and different process are used for each. It's not interesting enough to go into in any detail, but I used various types of planes for the most part. In particular, I used some new finger planes of different sizes, each of which was well suited to a particular contour. The top is spruce, which is very soft and easy to carve, whereas the back is maple and extremely hard. Three hours of carving the back and my hands had more than a couple of blisters. When the carving is getting close, getting the right thickness is extremely important. (Here's a place where measurements are needed). You can see in the picture above that I created a chart. I would measure various parts of the wood and write down the measurement so I'd know where to carve. Then it was just a process of continuing the measure and carve until the proper thickness was achieved.

Aside from the carving, most of the time has been spent on small details like gluing in the kerfing, and laying out, shaping, and gluing in the tone bars. The tone bars represent a major difference between the flat top and arch top guitars. Flat tops have intricate bracing systems and multiple tone bars. Since the carved wood of an arch top is much stronger than the flat pieces of a flat top, very little bracing is needed and the tone bars serve primarily to transfer sound throughout the top. Other steps since I last wrote include gluing the head and tail blocks to the sides, then gluing braces into them.

Cutting out the sound holes
But the most exciting development happened at yesterday's class when I cut the sound holes. This is a big deal because it required me to make a major decision about the appearance of my guitar. Most arch top guitars have "f" holes for sound holes (like you would see on a violin or cello), and I originally planned to do it that way. But in the end I decided I wanted to do something different so, after looking at lots of examples, I created my own sound hole design. The important thing is that the volume of the hole is about the same as the "f" holes would be, but an exact size or placement is not critical. It's important to remember that the purpose of the sound holes is not to act as a speaker, as many people assume, but to allow air to flow in and out of the instrument. It is this air flow that pumps the top up and down when the strings are strummed, making the top vibrate and produce sound.

So the holes are now cut and I'm very happy with my design. They still require lots of touch up, but I think they'll turn out well in the end.

The top after cutting the sound holes
I'm anticipating that the next few weeks will be tedious since the final carving and shaping will be done. But it shouldn't be long before it's time to glue it all together, and that's a very exciting part of building any guitar. Once that happens, you suddenly feel as though you're working on a guitar instead of just carving and shaping some old chunks of wood. And I'm about ready for that to happen.