Simple kinetic models

I was asked to do and online workshop and I came up with an idea for introducing beginners to making moving things. The idea is to build a single “engine” out of cork and wire (possibly a wire clip since they are easy to find) that can be moved back and forth between different contraptions. Building a single one also saves some time during a workshop.

The models can be built out of simple 3″ by 5″ index cards. And it’s nice to use the ones with a grid although they are less common. The grid makes it easy to mark the cuts and bends. The card itself also gives you a platform that can be pressed down with the cork when you are rotating the crank. Here are 3 models:

The first one is simply about turning rotary motion into reciprocating motion, notice how the wire fits into a long slit into the paper:

The second one is about how expressive paper can be with no straight creases, looks like a worm 🪱

And this one is about building a simple 4-arm linkage out of paper using a basic pop-up technique

A little wire bending can yield the next level of complexity with two alternating arms:

Mechanical Foamcore Models

I’ve been asked a lot about how to get started building mechanical contraptions and I always mention Keisuke Saka’s excellent book Karakuri, how to make mechanical paper models that move. The book has actual printed template pages that are meant to be torn out and used as building materials. The first time I encountered this book it was on loan from a friend that had built most of the models already, so I set out to replicate the basic mechanisms using materials that I was comfortable with, and that were quick and easy. Foam core, paper clips, skewers, paper, and plastic bits from yogurt containers.

I like this approach because paper craft can be intimidating for new makers as it requires patience an precision, and when it comes to working mechanical models it is sometimes easier to take a more forgiving approach.

These pieces are not new work. They were the precursors to the one month of small machines project so I wanted to document them even though they aren’t pretty. Page 6 of the books offers a summary of the basic mechanisms:

Most of the models are built on a foam core base that is roughly 2.75″ x 2.75″ by 2″. And for the completists out there, I didn’t build a Crank B.

Cam A – The rod makes a repetitious vertical motion
Cam B – Two rods make a vertical movement alternately.
Cam C – The rod makes a repetitious horizontal movement.
Cam D – The rod slides repeatedly in a linear motion.
Crank A – The rod sways repeatedly in a circular motion.
Crank C – The turning of the crank is converted into vertical motion.
Gear A – The gear turns horizontally to the handle.
Gear B – the gear turns perpendicularly to the handle.
Geneva Stop – A wheel makes turns in a discontinuous rhythm.

For making the gears I used I printed them on paper, glued on the foam core and then cut by hand. The Gear B needs some beveling to make it work.

This is a really good set of mechanisms to get started. Each mechanism will have a set of problems to solve, and solving these problems in whatever material you choose will translate to other materials. I like foam core and hot glue, but you might choose cardboard or wood. Good luck with your builds!

Also if you want an easy way to share these, grab them from my giphy channel here: Cam A, Cam B, Cam C, Cam D, Crank A, Crank C, Gear A, Gear B, Geneva Stop.