Slip Clutch

thingiverse

This is a mostly 3d printed slip clutch, so that you can drive something (like the angle rod on window blinds) without worrying about what happens if it jams. In addition to the printed parts, you also need a cotter pin (about 1.25" long) or a piece of approx 2mm rod, and a spring. Adjust tension by using a different set of holes. In the cutaway photo, the top is driven by a small motor, and the bottom is where the blind control goes (so, you would install upside down relative to the cutaway's view). While you can print a version from here, I suggest using the scad version from https://github.com/thatch/tim-open-things as it's easier for me to update (and get bug reports)