From the Loftsmith Workshop

Print-in-place crank automaton with bobbing ghosts

A little desk toy that puts on a ghost show. Turn the crank on top and the white ghosts pop up and down out of their purple slots, one after another. It prints already assembled, so there's nothing to put together. Change how many ghosts there are and how high they bob.

7 parts · 79 g · 95 × 95 × 108 mm

by Loftsmith Workshop

Purple round-based toy with a crank on top and white ghost figures standing in slots around it
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No adjustable sizes

Ask for the sizes you want to tweak, e.g. “make the width adjustable”.

Change it in the Studio

Parts

  • base · PLA · Upright as modeled, brim on the bed

    Witch-hat body: capture ring, band wall with 8 windows, 45-degree shoulder with chimney guides, 75-degree spire with the shaft bearing at the tip. About 42 g, 66 min at 2 walls/15%.

  • drum-crank · PLA · Upright as modeled, drum on the bed

    Drum with the wavy cam ring, 12 mm hollow shaft, scalloped knob and handle peg in one body. Captured in the base ring by 45-degree flanks. About 21 g, 42 min.

  • figure-1 · PLA · Upright as modeled

    Flat 3 mm figure with an engraved face on a 14 x 4 mm blade stem. Its foot tip starts 0.3 mm above a flat land on the cam, not on the bed. About 3 g, 15 min.

  • figure-2 · PLA · Upright as modeled

    Same as figure-1, 72 degrees round the ring.

  • figure-3 · PLA · Upright as modeled

    Same as figure-1, 144 degrees round the ring.

  • figure-4 · PLA · Upright as modeled

    Same as figure-1, 216 degrees round the ring.

  • figure-5 · PLA · Upright as modeled

    Same as figure-1, 288 degrees round the ring.

Print settings

Layer height
0.2 mm
Walls
2 walls
Infill
15%
Supports
None. Do not let the slicer add supports or a brim inside the hat; they would weld the moving parts.
Notes
Print the 3MF as one object so the gaps between the bodies are kept. At 2 walls and 15% infill the engine estimates about 82 g and 3 h 13 min for the default 5 ghosts; 3 walls/15% is about 111 g and 4 h 24 min. Run the hinge or tolerance tester first and set Joint clearance to the smallest gap that

Assembly

  1. Nothing to assemble: it comes off the bed as one piece.
  2. Let it cool, then lift each figure gently by 1 to 2 mm so its foot tip lets go of the cam land it printed on.
  3. Hold the brim with one hand and turn the crank peg slowly through a full turn; it should loosen within a turn or two.
  4. If the drum will not turn at all, the clearance is too small for your printer: reprint with the Joint clearance slider 0.05 to 0.1 mm higher.

Good to know

  • This design has not been printed yet. Freeing, friction and smooth bobbing still need a real test print.
  • Each figure's foot tip prints 0.3 mm above a small flat land on the cam, the way a support interface does. On some printers it may stick lightly and need a gentle lift to free it.
  • Bob height is limited to 14 mm. Above that, the friction estimate (PLA on PLA, mu 0.35) says the figures could stick in their guides.
  • The drum sits on the table next to the base and turns on it lightly. Hold the brim while you crank, because a sideways push on the peg can tip the 95 mm base.
  • The pumpkin, bat and tree outlines pass every check. The engine notes their narrow stem, ears and treetop as slender features high on the part, so print those a little slower.
I printed this Remix

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