improved Gear Shape for parametric_involute_gear_v5.1.scad

thingiverse

When using "parametric_involute_gear_v5.1.scad", I've encountered numerous issues with smaller gears - their teeth were breaking off. Examining the shape of the joint between the hub and each gear tooth revealed a very sharp edge, an absolute no-go for strong FDM printing - so I added a fillet to each tooth edge. Fortuitously, the gears mesh better, feeling much smoother when rotated by hand. I introduced a parameter called gearFillet to the module gear(), with my main code updates starting at line 430. The parameter defaults to true - allowing users to link in the library without needing any additional code changes. The difference is striking if you look at the first image; the new gear is on the left (cyan), while the old shape is on the right (orange).