To eliminate the ticking problem in the mechanism for the Umbrella Man, I decided to try adding O-ring snubbers between the pully shafts and the bearings. Because the O-rings are 1-mm in cross section, I was afraid that if I kept the original 5-mm shaft diameter, the shaft diameter in the O-ring grove of 3-mm might be prone to breaking (resin printed parts are fairly brittle). So I increased the shaft diameter to 6-mm. This necessitated going from bearings that were 4-mm thick to 3-mm thick, which required reprinting the baseplate.
In the bottom view you can see the white plugs which support an overhang which supports the bearings. They are printed with a special breakaway plastic and are easily knocked out after printing.
The pully is shown still attached to its support structure. With fused filament printing, a structure like this would not be required; it could print right on the printer baseplate, and it would detach as it cooled. With resin printing, there is no cooling, and parts have to be pried off the printer baseplate. Thus, most parts are printed on a sacrificial base, connected to the part by small posts. The touchpoints to the parts are very small, so these posts are easily broken away. This leaves small defects at the touchpoints, which in this case don’t matter, but otherwise they can be sanded away. Because the top edge of the O-ring and c-clip grooves was unsupported, they are slightly angled, but for this application this was better than dealing with the touchpoint artifacts.
