A hand-cranked creature
Turn a crank and make a character rise and fall. Build the movement in plain sight, then give it a world of its own.
About this project
A whale can surface, a strange head can appear from a hill, or a paper figure can pop up on a stage. Inside the box, one wooden rod turns a cardboard wheel. The wheel pushes a second rod up; that rod drops back as the wheel turns away. Your character rides on top. You can see the connections in the open box and change the scene around them.
Supplies
Materials & tools
- One rigid open-front box, roughly 15 cm wide × 10 cm deep × 15 cm tall
- Stiff card or two layers of shipping-box card: a 6 cm circle to lift the character, a 5 cm circle for the outside handle, and a 3 cm square platform
- Two smooth, blunt wooden rods about 4–5 mm thick: one about 23 cm long to turn across the box and one about 20 cm long to slide vertically; a short rod piece for the handle
- A straight straw piece about 3 cm long, wide enough for the upright rod to slide freely inside
- Thin card for a small character; PVA, a white glue suited to card and wood; tape, pencil, ruler, suitable scissors, and tools for a helper to make the holes safely
Before you start
- Choose a rigid box about 15 cm wide, 10 cm deep, and 15 cm tall. Leave its front open so you can reach and see the mechanism; tape the remaining corners firmly.
- Make a lightweight paper character, under about 10 cm tall, or leave that decision until the mechanism moves. Heavy decoration makes this small cardboard machine harder to turn.
Instructions
Put the turning rod through the box
Mark matching holes on the left and right walls, halfway from front to back and 8 cm below the top. Have the holes prepared on supported card, keeping hands out of the exit path. Slide the 23 cm rod through both walls. It should turn freely and stick out farther on the side where you want the handle. This turning rod is the axle. Tape a card patch around a weak wall before remaking its hole.
Cut the wheel that will lift your character
Cut a cardboard circle about 6 cm across. Glue two layers together if one bends easily, and let them dry flat. Mark the circle’s center. Make a second mark 1 cm to one side of it: the rod goes through this second mark, not the center. Have a snug hole prepared there. This off-center wheel is called a cam. The drawing shows where the hole goes.
Mark the middle of the 6 cm circle, then mark the rod hole 1 cm to one side. The rod goes through the off-centre hole. Fix the wheel to the rod so they turn together. That wheel is called a cam. Fix the wheel to the turning rod
Slide the rod partly out of the box, thread the wheel onto it, and put the rod back through the other wall. Position the wheel halfway across the box, standing upright like a car wheel. Glue it firmly to the rod on both faces and let it dry. Turning the rod should now turn the wheel with it. Because the hole is off-center, the wheel’s top rises and falls as it goes around. Turn it slowly and check it clears every wall; it needs about 4 cm of space around the rod.
Make the outside handle
Cut the 5 cm cardboard circle and fix its center to the rod outside one wall, leaving room for your fingers between circle and box. Glue a short blunt rod near its rim, pointing outward. You hold this little peg to turn the circle and rod together: that is the crank. Reinforce the glued joints with small card rings. Add tape rings around the long rod just inside the box walls to keep it from sliding sideways; leave gaps so the rings do not rub the walls. Let everything dry.
Rest an upright rod on the lifting wheel
Make a hole in the box top directly above the lifting wheel. Glue the straw upright in this hole. Its lower end must stay above the wheel’s highest point. Glue the 3 cm square platform flat across the bottom of the 20 cm rod and let it dry. From inside the box, push the rod up through the straw. Rest its platform on the wheel’s upper edge. Do not glue the platform to the wheel. The wheel pushes it up; its own weight brings it down again. The drawing looks from the handle side with that box wall left out.
Seen from the handle side, with that wall left out. The turning rod points into the picture at the dark centre dot. It turns the wheel, whose top edge lifts the platform and upright rod. Their weight brings them back down. The straw stays fixed to the box; the platform rests loosely on the wheel. Try the movement before adding a character
Hold the box steady and turn the outside handle gently. Watch the platform rise and settle while the upright rod slides through the straw. If it catches, stop and look at what is touching. Is the straw too tight? Is the rod leaning? Is a tape ring rubbing a wall? Move the parts rather than forcing the handle. If the platform tips, glue a small card triangle between it and the upright rod to hold them at a right angle. Let it dry, then try again.
Give the movement a character
Attach a light paper character to the top of the upright rod with a small card tab. Keep its weight balanced over the rod and try turning again. Then make a sea, a hill, a curtain, or another setting around it. Leave the moving rod and platform clear. Keep the front open so you can reach the connections when you want to repair or change them.
Troubleshooting
- The horizontal rod turns but the lifting wheel stays still.
- The wheel’s glued joint is slipping. Remove loose glue, add snug card rings against both faces, reglue the connection to the rod, and let it dry before turning again.
- The upright rod sticks or its platform falls off the wheel.
- Check that the straw is vertical, the platform lies flat over the wheel, and the horizontal rod is not sliding sideways. Make the platform broader if needed, keeping it clear of the box and turning rod.
- The box twists or the character will not rise.
- Stiffen the corners and remove heavy decoration. Turn slowly with the frame supported. Check for rubbing before making the crank stronger or pushing harder.
Where to take it next
- Make the moving figure and background into a tiny scene: a surfacing animal, a person at a window, or something nobody has seen before.
- Try a different lifting wheel when you want a different movement. Keep the original, and check the new wheel’s full turn inside the box before fixing it to a rod.
- Develop a waving or nodding figure with a separate pivot and linkage once the basic lift works. That adds a joint to design; simply gluing a heavy limb on top will not create the movement.
A closer look
The lifting wheel is round, but its hole is not in the middle. As the rod turns it, the distance from the rod to the wheel’s upper edge changes. That edge lifts the platform; gravity brings it down again. The straw holds the upright rod in one place while letting it slide. These connections turn your hand’s circular movement into a character’s rise and fall. You can use that movement in a scene of your own, or follow the cam link to explore the part separately.
What it needs to do
A function can have more than one solution. These options belong to this example; try alternatives thoughtfully.
box and shapes
A rigid box holds the moving parts. Layered card makes the two wheels, the little platform, and your character.
lifting the character
A cardboard wheel fixed off-center on the turning rod pushes a little platform up and lets it come down. This is a part you make from scraps, not a special component to buy.
turning and sliding rods
Two smooth blunt rods about 4–5 mm in diameter. One turns across the box; the other slides up and down through its top.
keeping the upright rod in place
A short straight tube holds the upright rod loosely enough to slide. It stays fixed to the box.
fixed joints
PVA suitable for paper, card, and wood; let layered card and axle joints dry fully.
temporary holding and collars
Tape holds dry-fitting parts and forms axle collars without binding the axle to the walls.