Thursday, May 8, 2014

A Big Problem...Solved!

How It Becomes Binding:

A Delicate Process Full of Peril

Before we got rolling on this next delicate part of buildmyguitar, Bruce Roper and I fortified ourselves with pancakes (Mine was buckwheat. Fantastic!) at Wishbone, just around the corner from his shop. That was fortunate because we would be needing the energy. Take a look at this:


That piece that goes around the outside edge of the guitar (in this case, a 1958 Martin D-28) is called the "binding," because it closes the seam between the bottom and top and hides some important brace ends that are exposed in the building process. You might think this would be easy to install, and at Martin these days, or other factories, it probably is because they have done it a million times and have worked out machines to complete the difficult parts.

 Not so at Bruce's. His guitars are hand-made. All of them. Each part.

Here is the body of my guitar on the table and ready to be routed for binding. A router is an interesting piece of equipment, basically a high speed electric motor with a razor sharp cutter on the end that spins thousands and thousands of times a minute. One might cut a guitar clean in half with a router, which, of course, is just not the objective at all. Bruce wants to cut a uniform groove around the top and bottom of the guitar so he can glue a very handsome dark wood and green binding around the top. It will kind of match the ring around the airhole on the top, but not exactly.

If everything about a guitar was square (and I'm talking about geometry here, not absence of coolness) this would be a simple process. You could put the router in a jig that put the cutter at a specific depth and height and just zip around the top.

But guitars are not square. If you have been following the blog, you might have seen an earlier entry in which the top of the guitar (and bottom) were set in special curved forms so they would each have an arch. That works very well, but not for the router. It means you can't get a guaranteed square cut along the top of the guitar, and that is irritating, not good and potentially damaging if anything goes wrong. A cutter spinning that fast will cut through sapele, which is hard wood, like it is cutting through butter, making a long trench in the wrong place. Bruce has constructed a bunch of solutions to help prevent this. Here is the one he set up first. Basically, it's like one of Thomas Jefferson's signing machines, lots of parallel things that float along and keep the router level and at the right depth. But once he had set it up, he didn't like the look of it. It would be a pity to wreck a guitar like this one, made from select woods and designed to be only mine and like no other one in the universe. A big hole in the top or side, of course, would make it distinctive, but, as you might have guessed, that's not the intent.


So he shifted to another option, a rig he designed and built himself that is free form, hand driven and good enough so that if everything goes exactly as planned, that groove will be just right. But nothing ever goes as planned.

This gives you a solid idea of what Bruce's rig looks like. But it doesn't tell the whole story. The bottom part of the rig is designed to ride along the side of the guitar to keep the router bit at the proper angle to the top, and the plate on the router is designed to keep the bit at the proper angle to the side. You really want that groove to be uniform, because the piece of binding that fits in it can take a little sanding from the top, which no one would notice except Bruce, but none from the side. It has to fit perfectly so that it is uniform as it marches around the top. (Bottom, too).

But...oh, shit! It's not working right. Some of the cut is perfect, but in some cases, the router jig pushes the cutter completely out of the groove because the top is just not level (and it's not supposed to be!) So these parts Bruce has to go over again, adjusting the angle of the router to make the cut just right. It's hard to imagine how invested I have become in this guitar, because I worried (needlessly as it turned out) at every point. The fact that the router burns the wood a bit and fills the shop with the smell of simmering sapele doesn't help (although it's a delightful smell.)

Also, that "just whip around the top and cut the groove" part isn't exactly right. Here is Bruce's schematic on how to cut a binding groove. He starts and stops for adjustments. Starts and stops because the heel on the vise holding the guitar gets in the way. Starts and stops so he doesn't go chipping any wood. Then goes all the way around the top in a different direction. This is a time tested formula. I suspect he wrecked a few guitars early in his life when he was working this out. I do not ask because he has won my respect. We all make mistakes in our careers. Bruce knows how to fix most of his.

After a nerve wracking 90 minutes, he finishes the job and starts filing the groove flat and fixing any little bumps he caused along the way. Here is how the guitar will look with its binding in place. But that can't happen for about another work because the groove needs to be prepared before anything gets glued in place.

The binding has to be soaked in water before it is installed so it bends without breaking.

We also discovered something I am not going to show you until the work is done. This guitar has an "eye" on the front, down below the air hole. Because it is a matched set that made the top, a couple of little growth rings come together just perfectly. It is as though a cyclops is watching you from down there. I love that, so natural and unexpected.

What was most interesting about this part of buildmyguitar was watching Bruce use the various rigs he has constructed to get specific jobs done. Dremel tools are a guitar maker's good friend, something Christian Martin did not have back in the 1830s when he started building fine guitars in New York. That gives you a good sense of what a craftsman he was as he built his way into American guitar history.

We finish this binding challenge next week, I suspect, then move on to the neck.

Please keep reading!

5 comments:

  1. What an intricate process!

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  2. Oh boy, oh boy! This is so exciting! All this wonderful work on a pancake for breakfast! No coffee nerves here...

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  3. What is the binding made of? I'm thinking wood,and what is the green material? TOOO interesting. What an artist!

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