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This mainly consisted of me cutting disks then forming and attaching them together to create the various components needed to construct the device. Everything used was constructed from raw materials except for the platter base. For that I sources an un-lubricated ball bearing square turntable from McMaster Carr. This was due to the fact that I needed to maintain a flat surface on the top for my drawing pad. For the rest of the pulleys I simply used the cutouts from various sized hole saws which I then routed down and sandwiched together so that I could keep my belt captive. The belt turned out to be necessary because using the turntable for the platter made locating the center of the hand cut "circular" platter an impossibility, these two issues lead to a run-out on the diameter of about 1/8" which was too much to make a friction fit gear mechanism maintain engagement. I subsequently opted for the pulley as mentioned which required I make a belt. The solution to that was liberating a bungee cord from its sheath then braiding it to keep the strands mostly in check and then whipping the ends together with nylon string. Due to the generous groves in my pulleys the belt runs well enough as is but this would be a good place to start should improvements become necessary.
Figure 4. Belt and Pulley / 4 bar crank closeup
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During the planning stages there was always an intention to include adjustability to the device such that link lengths and things of that nature could be readily changed to alter the output. During the build phase it became rapidly apparent that these settings would also make a big difference in machine performance. Certain configurations proved difficult or impossible to assemble, as well some lead to undesirable out of plane movements in the linkage, or at times would be close to binding making for smooth rotation difficult thus reducing the quality of the drawing. So some holes or positions that were initially planned for were either omitted or made obsolete based on heuristics.
Figure 5. Assembled Drawing Machine
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