The Crank Box is a 3D printed project to download and print out on your own 3D printer. The simple model demonstrates pure mechanism is action. The handle drives a gear, which in turn dri as second gear and finally a crank and push rod. See the model in animated action here. 

Here are the parts printed out and ready to go. I’ve printed them with PLA in a variety of colours to make a colourful model.

The joints are designed to be a tight fit. It should be possible to snap the models together without using any glue.

Once the parts are printed out, use this guide to assemble the model.

Pop one of the axle stubs into the larger gear.

Drop  the push rod over the axle stub. 

Clip the crank side into place.

Clip the second axle stub into place.

Fit the gear into position on the box side.

Drop the smaller gear into position in the side.

Thread the pushrod up through the top then clip the top to the side.

Fit the other side.

Fit the base into position. (The base is a second copy of the top)

Fit the handle to the gear.

Finish the model by fitting the handle to the handle crank.

Turn the handle to mesh the gears and crank the push rod!