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Laser Cutters and 3D Printers offer the shortest turnaround time for iterative prototyping while maintaining sub-millimeter precision. Precision at that scale is necessary for successful press fits and sliding fits which result in only one DOF. Most custom components of the mechanism were cut out of plywood, which offers several advantages. The compressibility of the wood gives greater margin of error for press fits, and the rigidity prevents non-planar forces from deforming linkages. In addition, laser cutting is the fastest digital fabrication method available on campus for low-volume production.
3D printed parts from PLA or PETG require time and effort to optimize for strength, surface quality, and tolerance. We minimized the number of 3D printed components, and ended up only making the gears, shaft drive adapters, and rail mounts with this method, which saved time in design.
Press fit bearings are crucial to the smooth operation of the mono-wiper. Each bearing mounted part was slightly undersized, and bearings were pressed into place using a vise. The same was done with the rotary shafts. We ordered 316 stainless steel shafts because linear shafts are often hardened, and cannot be cut down to length or otherwise machined without special equipment. the 608 bearings we ordered ended up with oversized IDs, so we used some 3D printed drive adapters as collars to keep them in place on the shaft.
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