Double Rack and Sector Pinion

cults3d

This is a demonstration of a mechanical setup consisting of a double-rack plate surrounding a sector pinion. Rotation of the center pinion causes alternating linear motion of the rack. Note that this is not reversible: driving the rack with alternating linear motion will not reliably drive the pinion, as there is a small amount of clearance in the middle of each rotation of the pinion where it is engaged with neither rack. The setup can be optionally driven by a small hobby gearmotor, available for about $3.25 each on Amazon or about $1.70 each including shipping from AliExpress. They're advertised as Car or Robot motors, and have standard dimensions. This GrabCad Model has proved accurate. Other hardware needed for assembly includes: * 6 @ m3 x 5mm knurled insert nuts * 2 @ m3 x 3mm knurled insert nuts (optional) * 2 @ m3 x 22mm or 25mm Bolt (I used hex-socket bolts, cap head would also be fine). * 4 @ m3 x 6mm Crown head machine screws * Two small pieces of wire for motor * Single AA Battery Holder * Switch (optional) Both the gear and the rack have a module of 3mm. The pinion has 6 teeth of a 20-tooth gear. The largest single piece (the racks) fits within a 200mm x 200mm build place easily.