IV. Manufacturing and Assembly - JV
The manufacturing and assembly of the mechanism was relatively easy due to the snap fit pin and joint assemblies. The first step in manufacturing was printing the 5 links, the spacer, and the ground pin for link 4. These were converted to STL's from CAD and sliced in CURA, they were printed with 70% cubic infill and a skirt to begin the print. The clearance given between link 3 and 4 worked well and the support was easy to clear, just to ensure smooth operation some sanding was done to make sure there would be no interruptions. Once all the parts were printed assembly could begin, the pieces were snapped together and put to the side so that I could look at the backing. The backing used was thin plywood, the motor would be attached to the face of the plywood; however, it had its wires coming out of the back, so two small holes were drilled in the plywood so that the motor could sit flat and maintain a large surface area of contact. The contact was important because the motor was attached using VHB an adhesive fastener. Once the motor was placed onto the backing the linkages could be added, the first thing to add was the spacer for link two. The next step was locating the ground pin for link 4, this was used using calipers and a protractor to find the correct placement. After the placement was found, the link 4 ground pin could also be attached using VHB adhesive, at this point the only thing left for the mechanism was the rails to constrain the output sliding link to horizontal motion. These rails were not printed due to the large amount of time it would take to print, instead they were bought from HomeDepot, they are simply 1/16" aluminum L stock with the square edges placed toward link 6. Using a level and link 6 the distance from motor output was measured to place the rail and the level was used to ensure that the rail was straight. Once the bottom rail was placed all that was left was the top, this was done with some finesse after trial runs of the mechanism to determine a good amount of clearance for the block to slide smoothly, too much clearance and the block could turn and get caught sideways. If it was too tight then there would be constant friction as the mechanism ran possibly causes failure or large deviations from the analysis done.
