Cow Jump

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Turn the handle on this paper automata and the cow jumps up and down in a completely improbable fashion!
The model uses a scotch yoke mechanism to drive the cow up and down and a simple linkage to make the legs move.
Members can of course download the parts for free, thanks for signing up! Non-members can download the parts for £2.50

Print out the three parts sheets onto thin card. (230 micron, 67lb)

Score along the dotted and dashed lines, cut out the holes then carefully cut out the parts.

Assemble the head and glue on the horns.

Glue the tab on the top of the neck to the inside top of the head.

Fit the neck into the body using the grey areas for alignment.

Fit the two body inners into place lining up the bottom edges with the bottom edge of the body.

Fit the leg inners front and back.

Glue the leg push rods to the leg inners lining up the end with the end of the legs (arrowed)

Make up the four legs by folding over card to make double thickness. Once the glue is dry, carefully cut them out.

Glue the legs to the leg inners. Make sure that you don’t get glue on the body, they should be free to move up and down.

Fit the main push rod into the body between the two leg push rods.

Fit the push rod slider tube to the box top the fit the box top stiffeners to the underside of the box.

Make up the two crank parts as shown.

Roll up and glue the three pins lining up the edges with the arrows.

Assemble the yoke. Glue the two slider tubes into place.

Assemble the crank inplace in the yoke. The long pin is in the centre.

Make the handle in three steps.

Thread the main push rod down through the slider tube in the box lid.

Glue the yoke to the end of the push rod so that it is lined up front to back with the cow and the tabs on the box lid are to the sides.

Glue the two box sides to the box lid as shown.

Fold the box side down and glue them together.

Thread the two pillars into the yoke slider tubes. Glue them into place top and bottom.

Finish off the model by gluing the leg linkages to the front and back of the slider tube and gluing on the handle!

Turn the handle and watch the cow jump up and down. Check out the Instagram animation here.