Perpetual Calendar

Behind the design

Peek into the KiwiCo product design studio and the design process behind the Eureka Crate Perpetual Calendar.

1. Different Drives

   1. Before we settled on the Geneva drive, we prototyped a few different drive mechanisms, like this giant spinning arm mechanism and this rubber band belt drive. But every drive we tried had trouble stopping the day tumbler at the right point, and always had a bit too much friction to work reliably. The Geneva drive was much more precise and way smoother.
2. Seven-Slotted Style

   1. Geneva drives aren't too common anymore, but if you find one, it'll probably look a little different than the one in your calendar. Most have four or six slots on the gear wheel instead of seven (this 4-slotted one is from an old movie projector). And they usually have just one pin on the drive wheel — yours has two so the drive steps forward every half-turn instead of every full turn.
3. Light Speed Lasers

   1. We did a lot of prototyping with the drives, tiles, and more, and it wouldn't have been possible without our fabulous in-house laser cutter. At the click of a button, we can send a design schematic from a computer to the cutter, and the cutter will zap the parts we need out of plywood. It's so fast that we sometimes add cute laser-etched details for fun, too.