How do you design a 3D printed spiral spring?
A lid that snaps itself shut. A wind-up toy that actually goes. Both need a spring that stores energy, and a coil isn’t on the menu in FDM. A 3D printed spiral spring, the flat clock-spring kind, packs a lot of twist into a small, flat space.
Applies to
- Process
- FDM / filament
- Features
- Self-closing lids, wind-up toys, return knobs, rotary mechanisms
- Orientation
- Printed flat, winding in the layer plane
- Not for
- Holding a part steady: see leaf springs
Why it matters
Most printed springs are stabilizers. They hold a part with a little give. A spiral spring is different: Slant 3D calls them energy storage devices, the kind you see in clocks.
All those turns packed tight is what does it. Wind it up and every turn stores a little twist. It’s a compact way to put rotation into a small space.
There are two dials, and they pull in different directions.
Make the whole strip thicker and it gets stiffer. That’s what you want for a spring that just opens and closes a lid.
Make the strip thinner, add more turns, and make the spring taller, and it stores much more energy over a longer wind.
Like every printed spring, it prints flat and twists in the plane of the layers. That also means you can print one inside a part as it grows, captive the moment the print ends.
What good looks like
- A flat spiral, printed flat, winding in the layer plane
- A modeled gap between turns, so they don’t fuse or rub
- Strip thickness matched to the job: thick for a lid, thin and tall for stored energy
- Rounded joints at the hub and the outer anchor
- Returns to the same rest angle after winding
How to apply it
- Decide the job: a stiff return over a small angle (a lid), or lots of stored energy over many turns (a wind-up).
- Draw a spiral with an even gap between turns, from a hub to an outer anchor.
- For a lid spring, use a thicker strip and fewer turns.
- For energy storage, use a thinner strip, more turns and more height in Z.
- Keep a modeled gap between turns so they print apart and don’t rub as they wind.
- Round the joints at the hub and the anchor.
- Print it flat.
Test it on your setup
- Print the spring with a hub you can turn and an anchor you can hold.
- Wind it to working angle and let go, a bunch of times. It should come back to the same rest angle.
- Too weak: thicker strip or a taller spring. Too stiff to wind: thinner strip or more turns.
Exceptions & tradeoffs
Mind you, plastic creeps. A spiral spring left wound for weeks loses some of its rest position. Design it to sit unloaded and only wind when it’s used.
A spiral twists. A zigzag pulls in a straight line. Pick the spring by the motion you need, not the one that looks cooler.
Common mistakes
- Turns drawn touching to keep the spring compactModel a gap between turns
- Printing the spiral on edgeFlat, winding in the layer plane
- Adding turns to make a lid spring strongerMore turns stores energy but softens it; thicken the strip for stiffness
- Storing the mechanism wound upLet it rest unloaded
Frequently asked questions
- Can you 3D print a clock spring?Yes. A flat spiral spring prints well in FDM because it lies flat and winds in the layer plane. It stores energy for things like self-closing lids and wind-up toys.
- How do you make a 3D printed spiral spring stronger?For more stiffness, thicken the strip. For more stored energy, use a thinner strip with more turns and make the spring taller.
- What is a 3D printed torsion spring?A spring that resists twisting. In FDM the practical version is a flat spiral spring wound in the layer plane, rather than a coiled wire-style torsion spring.
- Why does my 3D printed spring lose tension?Plastic creeps under constant load, so a spring left wound slowly takes a set. Design it to rest unloaded and only load it when it’s working.
Spiral springs as energy storage; thicker strip for stiffness, thinner with more turns and taller for more energy — Learn 15 Print-in-Place Mechanisms in 15 Minutes ↗ at 10:00.
Flat springs printed inside a part as it’s made — Learn 15 Print-in-Place Mechanisms in 15 Minutes ↗ at 10:58.
The energy-storage framing and the two dials (thicker for stiffness; thinner, more turns and taller for energy) are Slant 3D’s. The gap between turns, the creep caveat and the wind test are standard practice and my editorial notes.