BB Ratchet 0.1

thingiverse

The 0.2 version is superior to the 0.1 one; check it out at http://www.thingiverse.com/thing:207389. Tired of Christmas-themed prints, I decided to use my MakerBot for its intended purpose: creating machines. A diagram of a ball-bearing and spring ratchet piqued my interest as it seemed sturdier than an all-plastic alternative. The plastic part can be thick and robust while only needing to move a short distance, and the holding force is distributed evenly. Following the usual process, this design is experimental rather than practical, but it works well. Get the OpenSCAD file and customize it until you're satisfied. The concept is simple: four 4.5mm airgun BBs fit in ramps in the middle. Turning the ratchet one way rolls them down the ramps for a tight hold, while turning it the other way pulls them up to push against the ring for more friction. It's a snug fit that requires compressing the springs with the BBs already inside and narrow channels for the BBs. The center hole accommodates a 6mm hex-wrench or a 1/4" screwdriver head. I plan to make improvements in future iterations, such as: 1) Removing more material for easier forward spinning. 2) Deeper, wider notches for tighter backward latching. 3) Wider ramp channels for better BB fit. This design requires the util.scad file, mainly for my radial() function.