I had the opportunity to go to the Maker Faire last weekend -- I recommend it to anyone in the area (California Bay Area for this one; there's also one on the east coast of the USA). It's a lot of fun. People show off all kinds of projects they've been working on, from homemade forges and glassblowing to electric car conversions to robots.
One booth that I found particularly intriguing was demoing their
Cubelets, which they call "modular robotics" but which I'd rather call "logic blocks". Basically what you have here is a bunch of cubes, each of which either produces a signal (e.g. a light sensor, proximity sensor, dial), transforms one or more signals (e.g. invert, take the maximum), or acts upon a signal (e.g. a flashlight, wheel, bar graph). It's a great concept for teaching basic logic and robot design, marred only by the excessive price point. Though that clearly wasn't what the kids liked most about it: these are magnetic building blocks! They snap together! That's awesome!
So I'm thinking, there must be a way to build my own magnetic building blocks. Without all the circuitry they'd be cheaper and less damage-prone. The trick is coming up with a design that's functional, attractive, and hardy.
Here's attempt #1:
All this would require is a set of spherical magnets, a large-bore drill, and a saw. The spheres simplify magnetic coupling, since they can spin in their cages -- thus, the user doesn't have to rotate the block to get the right polarity matchup. However, there's some concerns with this design:
1) Because the magnets in a coupling don't directly contact each other, coupling strength will be reduced.
2) Magnets can chip or shatter, and you really don't want to eat bits of magnet (they can get attracted to each other in the small intestine and do serious damage to the walls).
3) Spherical magnets are expensive.
You can fix the shattering issue by removing the holes in the caps, but that further weakens the coupling strength. Preferable to having a health hazard in a child's toy though.
An approach that glued flat magnets onto the face of each cube would also work, of course. That's what the cubelets designers are using. In my experience, gluing small magnets by hand is very hard, especially if there are other magnets in the area. The magnets prefer to stick to your fingers rather than to the glue, and they prefer to stick to other magnets above all else. Also, unless you're willing to use 8 magnets per face of the block (in an arrangement with 90° rotational symmetry) the user will have to rotate their blocks to get things to match up.
Any thoughts?
