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Carving a 1903 replica
Martin Ivory Bridge
© Frank Ford, 3/17/00; Photos by FF, 0/00
I suppose I should make my position clear on the subject of ivory. I really don't condone the killing of elephants for their teeth. However, when it comes to the restoration of elegant antique instruments, I do support the use of recycled antique ivory. There are a few dealers in the U.S. who make ivory small part of their business, buying and selling old ivory artifacts and tusk sections. These bits of old ivory are clearly not subject to the international treaties, and, in my opinion, also free from any recent moral issue. I never use elephant ivory on any instrument that was not originally made with that material.
Here's a description of my order of operations in carving the classic
Martin "pyramid" bridge, as used on most all Martin guitars before 1929.
This one is a replica of a 1903 Martin 0-34's ivory bridge. Plainer models had ebony
bridges, of course, and the size of the bridge varied a bit depending on the model
This 0-34 had the largest size bridge normally used, which measured a full 1" by 6." That's my favorite size from the standpoint of "glueability," which can be an issue with ivory.
This is an unusual project because I'm not actually making the bridge for a specific guitar. Instead, I'm making it as a donation to the A.S.I.A. benefit auction for Symposium 2000, held in Nashville on March 26, 2000. It will undoubtedly be purchased by a luthier who will use it in restoring a vintage Martin guitar.
|Starting with a piece of antique ivory I got from Chuck Erikson, the "Duke of Pearl," I cut it to the 1" x 6" dimension of the original bridge, and to just a trifle under 3/8" thick.|
|There's nothing like having an original on the bench when you're making a copy! I marked the innermost boundary of the little radius inboard from the "pyramid" sections, and measured the radius, which turned out to be 3/16."|
|Using a 3/8" diameter chainsaw file, I was able to make the radius cut very neatly by clamping the blank in my vise right at the pencil line. That way, my file cut held a straight straight path downward as I held the file against the vise jaw. I made the cut right down to the final arch and thickness.|
|Next, I established the outer slope of the pyramid section at the same angle as the original bridge.|
|Using the inside arch as the lower limit of my cut, and watching the outside slope developing its pointy top, I used an 8" double cut mill file to form the side slopes of the pyramid, straight across and parallel to the sides of the blank.|
|This is a 10" single cut mill file with safe edges I rounded over on my belt sander. As I rounded the inner conical section of the modified pyramids, the safe edges kept the file from scratching the arched 3/16" radius cut.|
|I kept going back to the original to check the overall look and profile. Once I was satisfied with the pyramid ends, I was ready to smooth them up a bit.|
|The back edge of my 18mm violin knife has a nice flat surface which I true up from time to time, so I have a sort of a 90 degree scraping cutter. It works really well on this particular job, either for ivory or ebony.|
|In order to make the Martin bridge look correct, it's vital to make the conical section "sweep" around in a smooth curve without showing any vestige of back angles or corners.|
|To keep from rounding over the point, and the front corners of the pyramid, I did all my sanding with little blocks. This block is actually one of my favorites, a flexible 6" rule.|
|I worked at the pyramid sections until I had them sanded to 800 grit, true and scratch free. If I'm going to slip and mess up, it will be on these sections, so I get them right before starting to profile the center section|
|All my work is by hand, to avoid the possibility of slipping with a sander, or otherwise rushing. It would be a shame to nick the pyramid top at this easy stage of carving!|
|A final sanding of the center section to the same 800 grit finish, and I'm almost there.|
|Even when buffing, I was very careful not not lean on the corners or points, for fear of breaking their crisp detail edges.|
|Done! This bridge is just the same dimension and profile as the original, ready to be drilled and installed for restoring a fine old vintage Martin guitar.|