BB Ratchet 0.1

thingiverse

0.2 is much better than 0.1, see http://www.thingiverse.com/thing:207389 I got sick of printing xmas things and decided to have another crack at what I actually got a makerbot for -- making machines. I saw a diagram for a ratchet using BB's and springs which caught my interest, as it looks MUCH tougher than an all-plastic ratchet would be. The plastic spring part can be thick and tough, and doesn't need to move far at all. And the holding force doesn't get concentrated on the weak tip. You know the drill by now. This is an experiment, not a practical part -- even though I'm happy to say it works -- and if you want to use it yourself, get the OpenSCAD file and fiddle until happy. Instructions The principle is simple enough. The ball bearings, four 4.5mm airgun BB's, fit in ramps in the middle. When you turn the ratchet one direction, they are rolled down the ramps and stay there. Turn it the other, and they get pulled up the ramps to push against the ring, causing more friction. It is a VERY tight fit. You need to compress the springs to make it fit with the BB's already inside, and the channels are a bit small for the BB's. The center hole is meant to fit a 6mm hex-wrench or 1/4" screwdriver hex-thing. Improvements I intend for the next one: 1) Cut away more material for a looser forward spin. 2) Deeper, wider notches for tighter backwards latching. 3) Wider ramp channels to fit the BB better. This needs util.scad to work, mostly for my radial() function.