You just never know what's going to happen when you drop into a luthier's shop, even if you are expected. Here is Bruce Roper, the guy building my guitar, and he is saying...wait for it, "I'm giving you my awl." It's the kind of joke you have to expect in the world of wood. It's a knotty place that fairly splinters with wit, which is not a problem because you can just rub some epoxy on it to fix it!
Bruce Roper: Giving You My Awl
Enough jokes.We're moving into another important phase in the building of my guitar. I went to visit Bruce Friday afternoon to watch him run the two book-matched sides of the top through the drum sander so he can get them to exactly the right thickness. It's a meticulous process that involves caliper measurements in hundredths of inches. The sander, a rotating drum across a flat surface, shaves off just a hair with each pass. Shave then measure. Shave then measure.
Why is this happening? One reason is because it is nearly impossible to get a piece of wood to stretch all the way across the top of an acoustic guitar. These days, back and fronts of most guitars are constructed of two pieces of wood, sometimes cut in slabs from a thicker piece of wood, which makes them book matched.
|Checking one side of the top|
Bruce is inspecting one side to the book-matched top here. It's too thick and its edge has bloobies (I just made that up. It means unevenness) on the side that means it won't fit square against its other side. So job one is to move these sides through the drum sander to get to the right thickness. It's measured in hundredths and I'll be damned if I understand that scale. Job two will be to use another piece of equipment, a joiner, to plane hair thin slices of wood from the edges until the sides line up perfectly. This is where you begin to understand how fine the tolerances are in acoustic guitar building. It's a slow business because you are removing only tiny bits of surface each time the wood passes through the drum sander. The same is true for the joiner. Bruce listens when he is running the joiner until he hears no more burring on the edge. That means the sides of the top will line up perfectly when it's time to glue them together. Having repaired hundreds of guitars and built perhaps 50, he is comfortable not only with his tools, but with the challenge of getting everything to fit together properly.
|A shelf full of measuring tools|
|Sound hole and binding woods|
be used as one layer around the soundhole. The bigger bundle will be used for edging around the top and bottom of the guitar body. We're still thinking about what we will put up on the end of the instrument to make it distinctive. I'm thinking a rose will do for me. But we will see.
It took about an hour to get everything ground down to the proper measurements and flat on the edges. Then Bruce reached for a tube of epoxy, a much stronger glue than the one he will use on most other places on the guitar. Epoxy is a chemical glue that sets up harder than whatever it is holding together in most cases. That means the wood will break before the glue fails. Horse hide glue and other glues that can be melted with steam and water will be used elsewhere. You need that because sometimes you have to take a guitar apart to repair it. You can't do that very easily with epoxy without risking damage to the wood.
We were ready to glue the top.
Here's how THAT process looks, starting with:
|Putting glue on both edges of top sides|
|Weighting top with anvil to keep|
surfaces from buckling
Bruce uses a small set of wood wedges to force the sides of the top to push together. The anvil is a clever way to keep the top from moving as it dries. He uses a piece of granite on the other side. So, it's like a rig. He will give it a day or so to harden and dry, then begin working on the back, which will be a lot like the top (since it will match) but will have a little strip of hardwood down the middle.
This is moving along very quickly, which is what happens when you have a guy building maybe his 51st guitar. We're already talking about cutting the sound hole and building the rosette, which should be another good chapter in this story.
Next time, we're going to sit with Bruce's guitars in his living room and get him to tell us, literally, how they work.