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Chapter 3. BallistaMail > Skein Plates, Supports, and Their Attendant Mysteries - Pg. 73

MAKE: PROJECTS Eccentric Cubicle a matter of "whatever looks right." To achieve the much desired balanced skein, the bow arms are ideally located at the midpoint of the torsion skeins, such that the bowstring runs parallel and adjacent to the dart guide rails. Getting the midpoint of the skeins there calls for us to know where exactly there is -- which means having the guide rails in place and some of the winch components sized. [Figure 03.17] So, we gotta build some more stuff before we can proceed with the skein rack. The winch (windlass, actually) is gonna be hidden in the circular bit at the end of the body, with the cable feeding out of a hole in the top of the curve. Find the center of the circular rear section of the body, and drill it straight through the body to 3 / 8 ". Then, flip the body to expose the underside and plot the mayhem required to form the winch cavity. [Figure 03.18, Figure 03.19] As you can see, I took a fairly cavalier approach once I'd drilled through the body with the main cable exits here hole. I removed most of the material with Forstner bits, then tidied up the edges a bit with a high-speed cutting bit chucked into the drill press before pulling out the chisels and getting the cavity to look somewhat presentable. [Figure 03.20] The Guide Rail Mounts Remember those funky brass PEX T fittings we used to brace the skein rack supports? We'll use four of the next size smaller. These fittings are centered around 1 / 2 " brass cubes and are intended for use with 1 / 4 " tubing, but with a bit of drilling they'll accept 3 / 8 " OD tubing, which is what we'll be using as guide rails. Cut off all the extensions, leaving just the brass cube. True up the cut edges, drill out the crossing hole to 3 / 8 ", and drill a 3 / 32 " pilot for the mounting hole down through the other axis. [Figure 03.21, Figure 03.22] The guide rails need to run from just in front of the windlass cable opening on the top face of the body down the length of the body to somewhere in the middle of the skein rack -- in this case, 17" in length. So, rustle up some 3 / 8 " OD tubing and cut two 17" lengths. Slide your guide rail end blocks into place on each end of the rails; then use the block pilot holes as guides and drill though the rails with a 3 / 32 " bit. [Figure 03.23] The top faces of the front blocks need to be rounded out Figure 03.17: Examining the complexities of the windlass cavity and guide rod mounts Figure 03.18: The windlass axle hole Figure 03.19: The winch cavity roughed out . . . Figure 03.20: . . . and cleaned up. 62