Magnetic coupling

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.