Sunday, April 4, 2010

Forms, Patterns and Helpful Tools, Part 2

Patterns & Jigs
As I mentioned earlier, I purchased an Octave Mandolin kit from luthier Don Kawalek a few months back. The kit came with all of the necessary pieces and parts to build the mando. Also included were full scale plans and printed instructions for assembly. I decided, before beginning construction of the mandolin that I would make patterns for all of the wood components. I thought that it would be 1) a helpful way to 'practice' before jumping into the construction of the kit; and, 2) a great way to have the patterns for future octave mandolins that I will build. Included below is a picture of those patterns, as well as a couple of jigs that I will briefly explain.

The block with holes drilled in it pictured at the top is actually a jig that Roger H. Siminoff suggests making in his book, The Ultimate Bluegrass Mandolin Construction Manual. It is used for cutting the peghead angle on the band saw. To use it you simply set the neck on the jig and place a couple of spring clamps in the holes to hold the neck in place. Next, draw a centerline on the neck, trace out the peghead shape and cut it out. The pattern that I will most likely be using can be seen on the bottom right of the picture. Don’s kit offers two patterns, but I decided to make up my own. The tail and neck blocks can be seen on the left side of the picture, immediately under the neck. After cutting them out, I marked the angles, etc., on the patterns for future reference. You can also see a paper pattern for the sound hole. I used the ‘Paint’ program on my PC to get the oval shape and size correct. After I printed it, I marked center lines on it to line it up on the soundboard. The rectangular shaped block on the right is a jig for drilling the tuning machine holes. I drilled out the holes on the drill press at exactly 29/32” for 4-on-the-plate machine heads. I set this jig on the peghead and hold it in place with small brad nails and then drill almost through the peghead. Once all the holes are partially drilled you then want to take the jig off, flip the neck over and finish drilling the holes so you don’t have any tear out.

I also did a mock-up of a canted (i.e., bent) soundboard using an 1/4" piece of plywood (next time I would either use 1/8" ply or run a 1/4" piece under the Wagner Safe-T-Planer). I cut out the rough shape of the top, cut the soundhole, laid out the braces, glued them on, and then shaped them using a chisel. The brace pattern comes from McDonald's book. I have never done a canted top before so I simply wanted to see how the process would go, and if it would line up with the sides that came with the kit. In the end, I decided to do a simple induced arch top, so the canted top will probably be used on a future instrument. Here are some pictures. Again, this was only a mock-up, and so essentially 'practice'.

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