Magnetic coupling (Q38352)

This is a magnetic coupling concept that uses 10 of the Makerbot 3mm x 3mm x 3mm Neodymium magnets. These comes in handy when you need to couple two shafts together, but don't want to painstakingly axially align the shafts, within thousandths of an inch. I measured the holding torque of the coupling, with the magnets inserted into the couplings in both attraction and repulsion. I used a digital torque meter and analog torque watch, until the coupling slipped and recorded the data below. Attraction: ~43 in-oz Repulsion: ~25 in-oz Accepts a 12mm shaft diameter. I plan to make couplings that have smaller shaft diameters later and I am also working on magnetic gears. Update: Added 3/16" (4.8mm)ID coupling; accepts shaft size of a NEMA 17. Added a 1/4" (6.35mm) ID coupling; accepts a NEMA 23 sized shaft.