How do you 3D print a leaf spring or flex mount?
Something in your build buzzes, rattles or needs a little give, but it has to stay where you put it. A 3D printed leaf spring does that: a band of plastic that flexes a bit and springs back. Ring a few around a part and you have a flex mount. Put the ring in a lid and you have a push button.
Applies to
- Process
- FDM / filament
- Features
- Vibration mounts, stabilizer rings, push-button springs, guided sliders
- Orientation
- Printed flat, flexing in the layer plane
- Not for
- Storing energy: see spiral springs
Why it matters
Slant 3D sorts these as stabilizer springs. Their job isn’t storing energy. It’s holding something in position with a bit of compliance, and soaking up vibration.
The stabilizer ring is the simple one. An outer ring bolts to a wall or a frame, the part mounts in the middle, and a set of flat extension springs joins the two. It gives in the plane of the ring, so it steadies a transmission or anything else that shakes.
Push on it face-on and the same ring works like a trampoline. Slant’s example: build it into the lid of a box and it becomes the big red power button, pressing whatever switch sits underneath.
Leaf springs are a band of material flexing by itself. They can compress and slide side to side, and you get damping, give and return.
Put two side by side and it gets better. That’s a parallel mechanism: the part moves and depresses, but keeps its orientation the whole way.
The catch: they’re finicky. You only have one or two bands of material, so the main way to change strength is to thicken them. And stiffness climbs fast with thickness. Double the band and the leaf gets roughly eight times stiffer.
Then the rule Slant calls the most important thing with 3D printed springs. All the force has to be in plane, along the layer lines. Print a leaf spring at an angle and it has way less return.
A leaf spring can be a flat printed plate bolted into place, or a ring printed in plane with the part.
What good looks like
- Every leaf and ring printed flat, flexing in the layer plane
- Two parallel leaves wherever the moving part must stay level
- Rounded roots where each leaf meets the frame
- The part returns to the same spot after every push
- Stiffness set by band thickness, never by tilting the print
How to apply it
- Decide the motion: give in the plane (stabilizer ring), give face-on (button), or guided travel without tilt (parallel leaves).
- For a mount, draw an outer ring that bolts down, an inner mount for the part, and flat springs between them.
- For a button, put the same ring in the lid with the button cap at its centre, right over the switch.
- For guided travel, use two equal leaves side by side, joined at both ends.
- Start with one or two bands per leaf and tune stiffness by thickness, in small steps.
- Round the corners where the leaves meet the frame.
- Print it flat. If the rest of the part has to print another way, print the spring as a separate flat plate and bolt it on.
Test it on your setup
- Print the spring alone, mount it the way it’ll be used, and push it through its working travel.
- It should land back in the same spot every time. If it sags or drifts, thicken the bands a little.
- For a button, press it a few dozen times and check the travel still reaches the switch.
Exceptions & tradeoffs
Mind you, for storing energy, a lid that snaps shut or a wind-up toy, a leaf is the wrong spring. Use a spiral spring.
Thickness is a coarse dial. Because stiffness climbs with the cube of thickness, a 0.2 mm change can matter more than you’d guess. Step it slowly.
Common mistakes
- Printing the leaf spring tilted to save bed spaceFlat, with the force in plane along the layers
- One leaf where the part has to stay levelTwo parallel leaves
- Doubling the band to fix a soft springStep thickness in small increments
- Square roots where the leaves meet the frameRound them
Frequently asked questions
- What is a leaf spring in 3D printing?A flat band of plastic that bends and springs back, printed so it flexes in the layer plane. It holds a part in place with a little give and soaks up vibration.
- How do you make a 3D printed push button spring?Use a ring of flat springs as a membrane: the outer ring fixed in the lid, the button cap in the middle. Pressing the cap flexes the springs, and they push it back up.
- How do you make a 3D printed leaf spring stiffer?Make the bands thicker. Stiffness climbs quickly with thickness, so change it in small steps.
- What is a parallel flexure?Two equal leaf springs side by side, joined at both ends. The part they carry moves without tilting, which keeps it level as it travels.
Stabilizer ring for vibration, trampoline-style membrane, and the push-button example — Learn 15 Print-in-Place Mechanisms in 15 Minutes ↗ at 07:57.
Leaf springs, parallel mechanisms, strength set by thickness, and keeping all force in plane — Learn 15 Print-in-Place Mechanisms in 15 Minutes ↗ at 08:43.
The stabilizer ring, the push-button idea, the parallel leaves and the in-plane rule are Slant 3D’s. The cube-of-thickness note is plain beam physics I added so the thickness dial makes sense. The motion-first decision and the test are my editorial notes.