Lucky Lever Build

Reference

The 20 symbols

In flip order, 10 × 14 pixels of 4 mm each. Every symbol is split across two flaps: its top half on the front of one flap, its bottom half on the back of the flap before it. Tap one to pull the reel round to it.

Reference

How it works

Everything moves by hand. Two small mechanisms do the work, and both are printed.

Lever to reel ratchet

The lever's hex peg goes through the cabinet's right side, across the side bay and into the axle. The axle runs through the divider wall, with its tip in the spool. A 20-tooth ratchet wheel on the axle passes a flexing pawl in the bracket: it clicks once per symbol as the lever comes forward and stops the spool going backwards, where the flaps would jam on the stop fingers.

20 teeth18° per symbolpull forward and down

Knob to star Scotch yoke

The knob sits on a printed shaft that ends in an off-centre disc just under the roof. The star's shaft comes down through the cap and ends in a fork that straddles that disc. As the knob turns, the disc's centre moves side to side and the fork follows it, so the star rocks one way, back, the other way and back on every turn.

3.5 mm off-centre±24° swingturns either way

Reference

What you need

Tick things off as you gather them. The ticks are saved in this browser only.

No screws, glue, wires, batteries or coins. Everything presses, clicks or slides together, so the machine comes apart again the same way.

Reference

Fits and clearances

Measured on the 3D model with the knob turned all the way round (every 15°), the lever all the way round and the chassis sliding in: nothing collides. Parts that aren't meant to touch are at least 1.2 mm apart. Parts that turn, slide or press together use the fits in the second table.

Reference

Not tested yet

The model says these work, but none has been printed. If one is off, say what and by how much, and the part gets adjusted.

How the pawl clicks and how strong it is (a 1.0 mm PLA flexure), and how the longer lever feels on it.
The bracket's pegs in the divider's holes. If they're loose or crack, two M3 × 8 screws in the same holes replace them.
The axle's tip in the spool, and the lever's hex in the axle.
The gold knob on the printed shaft's D tip, and the cap's crush ribs in the roof window.
The two tall, thin shafts printing cleanly (53 and 49 mm, standing).
New on this cabinet: the coin tray's scooped floor (a 3 mm bridge at its bottom), the 777 marquee printed face down, and the thinner 5 mm front.