Magnet Unlock

Magnet Unlock is a magnetic puzzle inspired by a video by Andrew Klein. In that video, Andrew explains how magnetic flux can be short-ciruited, which is the basis of how magnetic switches work. The Magnet Unlock puzzle has three 3D-printed disks. Each disk has seven vertical metal rods, which are linked with rod magnets. The black markings indicate the "north" sides of the rod magnets. A rod with two north magnets has "+2 units of magnetic flux". A single north magnet means "+1 units of magnetic flux". Ditto for south magnets: "-2" and "-1". When the disks are stacked, the units of flux are additive, which means that the flux may cancel out.

The object of the puzzle is to stack the three disks in such a way, that the flux cancels out all together, and that the stack of magnets does not attract the steel plate. Of all 144 different ways of stacking, there is only one solution where the steel plate is unlocked. All other 143 ways leave the steel plate magnetically locked to the stack. Ditto for any combination of two disks, or a single disks. Only when all flux is short-circuited, the steel plate falls off.

The puzzle has 21 steel rods (e.g. 1018-grade steel for good flux conduction) with 13-mm diameter and 26.4-mm length, and 28 neodynium rod magnets with 6-mm diameter and 13-mm length.

Watch the YouTube video.
Read at the Shapeways Forum.
Read more at the Non-Twisty Puzzles Forum.

Please order a 3D-printed do-it-yourself puzzle kit from Shapeways at this page (check with Oskar about steel rods and magnets), or contact Oskar directly if you are interested in obtaining a fully colored and assembled sample of this puzzle.

Many thanks to George Miller, who sponsored the steel rods for this puzzle.