I want to build an archtop guitar. Why? I've built violins and violas. I have a cello started. I made a 1/2 scale 5 string guitar for the grandsons based on a 5 course Stradivarius baroque guitar. I don't play the violin. The guitar is with the boys. My old classical that I got at a garage sale 30 some years ago is in need of repair. The neck has always been bent. The saddle is coming unglued. The action is too high. The frets are pretty low. It's unplayable.
I could just fit it up. But then I saw this:
It was on a Chicago guitar makers site:
http://koentoppguitars.com/blog/the-hog-amati/
There is a whole lot of inspiration there. So I looked in my stock of wood, and the only thing I seemed to be lacking was a belly. I can use the top part of a board I bought to replace the back on the cello I have started. I hacked the first one one while sawing the wedge in half, and it will be not as high of an arch as I wanted. It isn't spectacular; but it is a one piece European Sycamore slab. That's maple for us.
I can use one of my rib blanks for the cello, and split it lengthwise for the sides. A piece of Birdseye maple can be cut off a piece that will be a viola back to make two sides of the neck, and the headstock. A piece of Padauk can go in the middle, and house the truss rod. I know NOTHING about those. A cool piece of curly Bubinga will work for the fingerboard. I found a piece of older curly redwood at Orcas Island Tonewoods in the specials page.
http://www.radiofreeolga.com/tonewoods/specials.html It looks very cool. It does seem like I'll have to be careful about the cross gain stiffness. When it gets thin you can snap it. Any tips about that? Once it is glued around the edge it should be better. Double it from the start? Line the f holes?
I drew it up 400 mm wide by 500 mm long. Just about 16 inches. I couldn't go much bigger because of the size of the maple. That also gave me enough wood on the Redwood before sawing it to book match to give me 2 parallel braces. I made a copy of the rough plan, and glued it on to a piece of 1/4" hardboard for a pattern. I still need to make a form. That will be the first real step. But I have done some planning.
(Yeah, I know that drawing has a REALLY DEEP dovetail. That was before I bought a book to give me the basics.)
I make violins and violas from the inside out. A bit weird maybe, but I think it is the right way to do it. Why? Well think of the shape. It follows the outline, and the arching almost like a fabric made up of lines connecting each point to the next. When we get into it you will see how it works. I worked out the inside and outside arches today, not perfectly, just with sketches based on cross arches, catenary curves that I drew up. I bought the Benedetto book on making Archtops. It doesn't have the things I was looking for. I'm always looking the opposite way that everyone else does. But the arches I drew up today match the long arch profiles almost exactly.
A catenary curve is what you get when you hold a chain on both ends, and let it hang. You see them all the time. Bridges are made with them going upwards. Electric lines show them going downwards. The steel trucks that come into our shop, (I'm a CNC machinist), have beds that are catenary curves. Loaded with bar steel they look almost flat. Empty they rise up maybe a foot. But that is just part of the curve, the rest, the outside edge, is the re curve. It can be thought of as a spring. It is a curate cycloid. It is what you would make with a Spirograph if you use the straight bar and any wheel. The smaller the wheel, the narrower the arch. The further from the center, the higher the arch. You have to decide where the low point will be. A lower, wider arch can go further in from the edge. A higher, narrower arch can go closer. On an archtop, it doesn't change dramatically; the narrow point is not that narrow, and the arch is not really that high.
Check in and see how it goes.
Ken
There is a whole lot of inspiration there. So I looked in my stock of wood, and the only thing I seemed to be lacking was a belly. I can use the top part of a board I bought to replace the back on the cello I have started. I hacked the first one one while sawing the wedge in half, and it will be not as high of an arch as I wanted. It isn't spectacular; but it is a one piece European Sycamore slab. That's maple for us.
I can use one of my rib blanks for the cello, and split it lengthwise for the sides. A piece of Birdseye maple can be cut off a piece that will be a viola back to make two sides of the neck, and the headstock. A piece of Padauk can go in the middle, and house the truss rod. I know NOTHING about those. A cool piece of curly Bubinga will work for the fingerboard. I found a piece of older curly redwood at Orcas Island Tonewoods in the specials page.
http://www.radiofreeolga.com/tonewoods/specials.html It looks very cool. It does seem like I'll have to be careful about the cross gain stiffness. When it gets thin you can snap it. Any tips about that? Once it is glued around the edge it should be better. Double it from the start? Line the f holes?
I make violins and violas from the inside out. A bit weird maybe, but I think it is the right way to do it. Why? Well think of the shape. It follows the outline, and the arching almost like a fabric made up of lines connecting each point to the next. When we get into it you will see how it works. I worked out the inside and outside arches today, not perfectly, just with sketches based on cross arches, catenary curves that I drew up. I bought the Benedetto book on making Archtops. It doesn't have the things I was looking for. I'm always looking the opposite way that everyone else does. But the arches I drew up today match the long arch profiles almost exactly.
A catenary curve is what you get when you hold a chain on both ends, and let it hang. You see them all the time. Bridges are made with them going upwards. Electric lines show them going downwards. The steel trucks that come into our shop, (I'm a CNC machinist), have beds that are catenary curves. Loaded with bar steel they look almost flat. Empty they rise up maybe a foot. But that is just part of the curve, the rest, the outside edge, is the re curve. It can be thought of as a spring. It is a curate cycloid. It is what you would make with a Spirograph if you use the straight bar and any wheel. The smaller the wheel, the narrower the arch. The further from the center, the higher the arch. You have to decide where the low point will be. A lower, wider arch can go further in from the edge. A higher, narrower arch can go closer. On an archtop, it doesn't change dramatically; the narrow point is not that narrow, and the arch is not really that high.
Check in and see how it goes.
Ken
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