Kinetic Wave Sculpture - a free 3D model from Shapekit

A row of 32 slats on a camshaft. Every slat is a scotch yoke: a flat frame around its own eccentric cam, so the cam lifts it 20 mm and pulls it back down on every turn. Each cam sits 22.5° further round than the one before, so the crests on top of the slats make two full waves that roll along while you turn the crank. The cams are all the same part: the key on top of each one fits the socket of the next only one way, turned 22.5°, so the camshaft can't go together wrong. Half the slats always go down while the other half go up, so the crank turns evenly. Nothing needs supports.

Parts (each STL is already placed the right way up for printing)
- wave-sculpture-base.stl: Holds the two end plates in grooves. Four M3 × 12 screws come up from below into the plates. Print: Flat. No supports.
- wave-sculpture-end-plate.stl (print 2): Carries one end of the camshaft in a countersunk hole, and the comb and the rail at the top on four M3 × 16. Both ends use the same part. Print: Flat on its side. No supports.
- wave-sculpture-cam.stl (print 32): A disc 36 mm across, 10 mm off the axis, with a key on top and a keyed socket underneath. The socket is turned 22.5° from the key, so every cam sits 22.5° further round than the one below it: 16 cams make one wave. Print: Disc down, key up. No supports. Scrape off any elephant's foot, so the slat around it doesn't rub.
- wave-sculpture-journal-left.stl: Its key goes into the socket of the first cam, and its round end turns in the left end plate. Print: Standing on its round end.
- wave-sculpture-journal-right.stl: Takes the key of the last cam, turns in the right end plate and carries the crank on its hex. Print: Flange down, hex up.
- wave-sculpture-slat.stl (print 32): A scotch yoke: the window goes around one cam, which lifts the slat and pulls it down 20 mm on every turn. The thin stem slides in the comb, and the crest on top is one line of the wave. Print: Flat, as in the file. Turn on elephant's foot compensation: the slats are 4.4 mm thick at a 6 mm pitch.
- wave-sculpture-comb.stl: 32 slots, one for each stem, open at the front so the slats slide in. It keeps them upright and in line. Print: As in the file, the slots standing up. No supports.
- wave-sculpture-rail.stl: Closes the slots of the comb at the front. Print: On its side.
- wave-sculpture-crank.stl: Fits on the hex of the right journal. The dome nut on the rod holds it on. Print: Flat, pin up.
- wave-sculpture-knob.stl: Turns on the crank pin, held by an M3 × 8 and a washer. Print: Standing up.

Also needed (not printed)
- 230 mm of M4 threaded rod (cut from a 1 m rod and file the ends), 2 M4 dome nuts and 2 M4 washers.
- M3 screws: 4 × 12 for the base, 8 × 16 for the comb and the rail, 1 × 8 with a washer for the knob. They cut their own thread in the plastic.
- Optional: dry PTFE spray or a little silicone grease for the cams.

Print settings: 0.4 mm nozzle, 0.20 mm layer height, 3 walls, 15% infill, PLA or PETG material.

Assembly
1. Print the parts: Nothing needs supports. There are 32 cams and 32 slats, so print them in batches. Turn on elephant's foot compensation, or scrape the bottom edges of the cams and slats, so neighbouring slats never touch. Check that a cam's key drops into the socket of another cam.
2. Frame: Stand the two end plates in the grooves of the base and screw them on from below, two M3 × 12 each. Push the left journal through the left plate from the inside, so its flange is on the inside, and the right journal through the right plate.
3. Start the camshaft: Push the rod through the left journal from the outside until it is flush with the key. Lay a slat over a cam, the cam's disc in the window and the side of the slat that was on the print bed facing left. Hold the cam's socket against the key of the journal, turn it until the key drops in, and push the rod on through the cam.
4. Fill the row: Do the same with the other 31 slats and cams: slat over cam, socket onto the key of the cam before, rod through. Every cam only fits one way, so the waves come out right by themselves. For the last one, pull the right journal out a little, line up its socket with the last key, push it back and push the rod through it.
5. Comb and rail: Stand the slats up so all stems point straight up. Slide the comb in from behind, between the end plates, so every stem goes into its own slot, and screw it on with four M3 × 16 through the plates. Screw the front rail on in front of it the same way.
6. Crank: Slide the crank onto the hex and put a washer and a dome nut on both ends of the rod. Tighten them firmly: they clamp the cams together, so the keys don't rattle. Put the knob on the crank pin and hold it with an M3 × 8 and a washer.
7. Turn it: Turn the crank slowly the first time. If a slat catches, check that it faces the right way and that its stem sits in its own slot. A puff of dry PTFE spray on the cams makes it run quieter.

Safety: Small parts and screws: keep them away from young children.

License: Creative Commons Attribution-NonCommercial 4.0 (CC BY-NC 4.0)
https://creativecommons.org/licenses/by-nc/4.0/
Print it, remix it and share it, as long as you credit Shapekit and don't sell the files or the prints.
