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Chapter 3. BallistaMail > Foreign Words: Fabricating the Epizygis and Modiolus - Pg. 82

Ballista Mail the tip of each arm. This design permits an extended range of retraction without risk of having the flippin' bowstring slip off the end of the arms in mid-demonstration. Serendipitously, the bowstring also acts as a shock absorber, cushioning the impact of the bow arm against the support column during operation. Shown is stack of two three-ply bow arm blanks; they're laminated from 1 / 4 " poplar, red oak, and poplar again, with the grain of each ply running about 15 degrees off parallel to add a bit of strength. The blank is about 6 7 / 8 " x 2 3 / 4 ". You can use solid, unlaminated hardwood if you want. The grain strength improvement from lamination is a nice bonus, but not necessary if you use clear, straight-grained maple. Draw your arm onto the blank, and drill the bowstring holes before going any further. [Figure 03.43] I roughed the arms out with a coping saw. The discoloration you see in the wood is from the appalling amount of sweat generated by the process. The curve geometery came from using a French curve to connect a few circles, and I used the entire length of the blank, which leaves