Crank/Cam Essential Mechanism. Turn the handle and the main push rod turns once per turn of the handle while the slip sleeve move three times per turn. This mechanism is at the heart of the Die Fledermaus model and the Flying Santa projects. Use this Essential Mechanism as the starting point for your own animated character designs or as an exercise in pure mechanism!
Print out the parts onto thin card. (230gsm / 67lb) I used coloured card for a colourful model. You could use white, coloured or patterned card as you choose. Score along the dotted and dashed lines and cut out the holes before carefully cutting out the parts.
Some of the parts are made from double thickness card for extra strength. Fold them over and glue them down. Once the glue is dry carefully cut them out.
Assemble the two crank sections.
Roll up and glue the four axle tubes lining up the edges with the points of the triangles as accurately as possible.
Thread the two crank ends onto the shortest axle tube and glue them to the marked area on the push rod. The axle tube should turn freely in the crank ends.
Glue the crank pieces to the axle tube as shown.
Assemble the slider tubes.
Glue the cam follower holder to one of the slider tubes.
Glue the longest axle so that it is centred in the cam follower tube.
Glue two of the spacers to the top of the follower assembly.
Glue the other two spacers to the other slider tube.
Slide one of the cams onto the crank. Make sure that it is oriented the same way as in the picture. Glue it to the side of the crank piece.
Glue the other cam into position as shown.
Slide the cam follower assembly down the push rod as show. It should move freely up and down the push rod.
Slip the other slider tubes into position.
Assemble the two long links. Use them to link together the spacers on the slider tubes as shown.
Find a small coin. (20mm diameter / 4 grams) A UK penny is ideal. Wrap it tightly in an off-cut of card.
Glue the coin to the front of the cam follower assembly in the position shown.
Fold up and glue the two sides.
Fold up and glue the box top and box base.
Glue together the four sections of the box as accurately as possible. Note that the circular holes are closest to the base piece.
Fold round and glue the box.
Thread the push rod up through the hole in the box top and glue the lower slider tube to the tab.
Fit the two remaining axles in through the box holes into the crank.
Assemble the handle in three steps.
Glue the handle into place to complete the model.
The completed model
What animated character will you design for yours?