Fixes for Ferguson's Mechanical Paradox Replica Thingiverse #93418

thingiverse

The attached files include replacement top, bottom, and connection pieces for the project outlined below. Spending time experimenting with various gear designs and testing led me to come across Ferguson's Mechanical Paradox Replica, posted by sawdusty on May 24, 2013. He mentioned that he had not printed the design and was unsure if it would function. Despite these uncertainties, the project piqued my interest, so I decided to try creating it. After printing the parts as shown in the photos, several issues arose: 1) The holes for the pointers on the gear shafts were too small to print accurately. Using CuraEngine with a 0.35mm nozzle did not produce successful results; the pins on the pointers proved particularly fragile. 2) The pointers did not nest together properly due to inadequate clearance for smooth interference-free movement. 3) The shafts on the base for the gears were oversized, making it difficult to insert the gears securely. 4) The attachment holes were absent from the base plates. 5) The attachment pins were extremely brittle when printed with ABS plastic. Placing them on their sides and cleaning off supports without breaking them may be a viable option. 6) Slic3r was unable to work effectively with the gears, causing frequent crashes under MatterControl. I resorted to using CuraEngine instead, achieving success despite initial difficulties. Using a 0.5mm nozzle led to significant "waisting" or dishing in toward the center of the gear during printing, making gear meshing problematic. Switching to a 0.35mm nozzle significantly reduced this effect. Lacking access to the design files, I did not attempt to modify the gears. The attached files address the issues with the shafts, pins, and attachments but do not rectify the problems with the pointers. Printing at 60% infill for the gears and mechanism ensured their stability, while printing the base at 80% infill helped strengthen the pins. The prints were made from ABS plastic.