Turn the knob. Fifteen feet take turns.

Sandwalker is a hand-cranked walking machine on 15 Jansen-linkage legs. One crankshaft sets every leg 45° behind the last, so the feet roll onto the ground one after another and the body glides along almost level.

The Sandwalker seen from the front corner: sand-coloured upper triangles, violet and grey links, green and pink parallel bars, and brown triangular feet, with the red crankshaft running through the middle.

It starts at the red knob.

Everything that moves is driven from the handle on the end of the crankshaft. There is no motor and no battery; your hand is the engine. Scroll, and it turns.

One shaft, 8 crank pins.

The crankshaft carries 8 pins, each set 45° further round than the one before, so a single turn of the knob sends a wave down the whole machine.

Each pin works a pair of legs.

7 of the pins drive one leg on each side; the pin nearest you drives one. Every pin pushes and pulls two violet and grey links: one up to a triangle, one down towards a foot.

The linkage draws a loop.

The sand triangle rocks on a steel axle, the green and pink bars carry the motion down, and the brown foot traces the blue line: a long flat stroke along the ground, then a high return through the air.

Fifteen feet take turns.

At every point in the turn, between 5 and 7 feet are planted. Before one lifts, the next is already down, so the machine never has to lurch.

And it walks, level.

Each turn of the knob carries it about 12.1 in, and the frame rises and falls by less than 0.5 mm on the way. That is the whole trick of Jansen's linkage.

A flat stroke, then a high step.

This is the path one foot follows in a single turn of the knob, solved from the joint positions in the model. The heavy stretch is the part it spends on the ground: nearly straight, so the body is carried level instead of bobbing. The rest of the loop lifts the foot 1.6 in clear and swings it forward to start again.

Travel per turn
12.1 in
Foot lift
1.6 in
Frame bob
under 0.5 mm
The path one foot traces in one turn of the knob
The first leg, seen from the side, walking left to right. Ground stroke drawn heavy.

Never fewer than 5 feet down.

Each row is one leg, sorted by the moment its foot lands; each bar is the stretch of one knob turn when that foot is on the ground. A foot is down for about 38% of every turn. Because the pins are staggered by 45°, the landings step evenly across the turn, and there is no moment when the machine stands on too few.

Which of the fifteen feet are on the ground through one turn of the knob
Knob at the start of a turnOne full turn later

Legs on the left side Legs on the right side

The Sandwalker from the rear corner, with the red crank handle on the grey end plate at the left and a row of brown feet casting perforated shadows.
From the knob end. The left and right legs are mirror images, and both sides push the same way.
Close-up of the red crank handle on the grey end plate, with violet links, sand triangles and green bars around it.
The handle sits on the end plate, where one finger can keep it turning.

Sandwalker

A walking kinetic sculpture you print and assemble, rebuilt at 1:4 from Zolko's CC0 FreeCAD Sandwalker, after Theo Jansen's beach walkers.

Assembled size
20.8 × 16.9 × 12.8 in
Legs
15, on 8 crank pins set 45° apart
Printed pieces
239, from 17 part designs
Steel in the design
2 axles, 6 × 400 mm, and 8 ISO 2338 dowel pins as crank pins
Drive
Hand crank, no motor
Travel
About 12.1 in per turn of the knob