Creatrope

What’s a cemetery scene during Halloween that doesn’t have at least a few buried undead trying to join the fun?

Here’s a ten minute project that converts a static foam Halloween gravestone into an animated rocking gravestone. Animated props are much more interesting than static props, but its a ’slippery’ slope into powerful motors and pneumatics – or expensive store-bought goods. Why not try to make one using materials you have around?

Materials

A K’Nex Motor (you can see the one I used, but various motors are adaptable – including erector set motors).

A foam gravestone

A piece of wood to mount them on.

An industrial stapler (preferred) or alternative way to make a hinge (several bent nails would also work).

Glue gun (preferred) or duct tape.

Assembly

Mount one of the plastic stands firmly into the foam at one end of the gravestone. This will be your fulcrum so it needs to be solid. Use a glue gun or duct tape to ensure it is firmly installed and at right angles to the gravestone. Ordinarily you’d mount the second one to keep the gravestone upright, but in this case it won’t be needed.

Staple the stand into the base in a few places. It should be tight enough so it does not rock side to side, but it does pivot up in the direction of the fulcrum. There’s lots of ways to mount it so it rocks, but the staples are quick and convenient.

Mount the motor as shown to the board. I used an industrial stapler to mount the motor to the board using K’nex stabilizing cross-pieces.

Make a cam gear as shown on the shaft of the motor. There’s no magic to this particular gear – any asymmetric gear on the shaft of the motor will ‘rock’ the gravestone.

Assemble motor and shaft and align gravestone so one end of the base rests neatly on the cam. As the cam rotates, it will ‘rock’ the gravestone. The cam k’nex is not smooth so the gravestone jitters irregularly – as if something were pushing it from underneath.

Testing/Alignment

You may need to experiment with various cams and distances depending on the weight of the gravestone or alignment.

If you like what you’ve got, a dab of glue in key places will give it a better chance to survive until next Halloween.

Cover the wood base with black plastic, leaves, whatever.

Elaped time, 10 minutes! Congratulations on turning a static halloween prop into an animated prop!

Send me your photos of your rockin’ gravestones and I’ll add them here.

If you liked this prop, you might also check out:

A Modular Halloween With Grid Beam

General Grievous animated costume

PVC Halloween Mannequin

AVR Robot Halloween Costume

Godzilla Halloween Costume

Note: this was inspired by another animated gravestone (significantly more elaborate than mine and definitely not an impromptu project) that I found in the Monster List of Halloween Links. I’d love to credit it, but I’m unable to relocate the link. I’ll be happy to add it if someone assists me in finding the source material.