Haunted Graveyard Automaton - Turn the Crank: Ghost Rises, Skeleton Hand Claws Out, Pumpkin Hops (No Supports)

Turn the crank and the graveyard comes alive. A ghost rises from behind its tombstone, a skeleton hand claws its way out of an open grave twice every turn, and a jack-o'-lantern hops in the pumpkin patch, each at its own moment, so something is always moving. Gothic windows in the crypt let you watch the cams turning inside.

HOW IT WORKS

• Three cams on one crankshaft lift three followers up through guides in the graveyard deck. Gravity brings them back down.

• Each cam is a flat-follower cam worked out for its figure: the ghost rises 18 mm once a turn, the hand 10 mm twice, the pumpkin 8 mm twice, all out of step with each other.

• The cam profiles are symmetric, so it runs whichever way you turn the crank.

• No screws, springs or glue: a D-shaped shaft keys the cams, tubes space them, and a collar and the crank hold it all together.

PRINTING

• 3 plates, no supports: crypt base, graveyard deck, and the mechanism with the figures.

• The 3MF is set up for 4 colours (grey crypt, green graveyard, orange mechanism and pumpkin, white ghost and hand). It prints just as well in one colour per plate.

• Bambu Studio: 7 h 39 and 198 g for everything.

ASSEMBLY

1. Slide the shaft (flat side keyed) through the left wall, then a short spacer, the G cam, a long spacer, the H cam, a long spacer, the P cam and the other short spacer, and out through the right wall.

2. 2. Push the collar onto the left end and the crank onto the right end.

3. 3. Push the three followers up through the deck from underneath and press the figures onto the rods: ghost on the left, hand in the middle, pumpkin on the right.

4. 4. Lower the deck onto the crypt so the four pegs drop into their sockets, and turn the crank.

5. CUSTOMIZE (OpenSCAD)

6. The sliding-fit clearance and the name on the crypt ("HAUNTED HOLLOW").