Plastics are wonderous materials, much loved for their ability to elastically deform and spring back to their original shape. They’re a category of materials perfect for creating things like living hinges and similar mechanisms, and this 3D printed snap action device shows that off admirably.
The device consists of an outer housing, into which two printed springs are inserted. These leaf springs are curved and protrude towards the center of the housing. A slide is then inserted into the housing with a cam in its middle. The cam allows the slide to push past the springs when actuated, while also holding it in place at rest.
As demonstrated the mechanism reliably snaps back and forth between its two positions in a satisfying manner. It’s shown with one side of the housing removed so we get a good idea of how it works. It’s 100% 3D printed, as well. Anyone looking to replicate the design should note the importance of printing orientation, particularly in the case of the spring pieces, which won’t work if layered up in the wrong way.
Overall, it’s a neat design that could prove useful for those eager to build printed switches or other mechanical devices. It’s also simply a great way to learn about 3D printed springs and working with deformable plastic structures. Video after the break.
7 thoughts on “Simple Snap Action Mechanism Is 100% 3D Printed”
That is very cool! There’s something just so simple, elegant, and satisfying about designs like that. I have to wonder if it was made simply as a demonstration, or if it has a larger purpose.
I also wonder if it would suit its purpose as well with only one leaf spring and one cam bump. Then it would be narrower and would require one less part. It might bind and wear a bit on the non-cam side, but that might be an acceptable trade-off.
Pouches for M1910 Cartridge Belt used exact same mechanism for buttons. Worked good enough for WWI, WWII and Korea.
These are often uploaded as “fidget toys”, but of course can be used/modified for use as a switch. Here’s another example: https://www.printables.com/de/model/218996-fidget-toggle-switch-compact-remix
Those get quite “sloppy” when used a lot and printed in PLA. There are many magnetic versions as well…
I suppose that to use them as switches, you glue some copper strips to the right places?
Reminds me of the power switch on my old coffee machine
Here’s the link to the year-old project that the reporter omitted from this article for some reason, in case anyone wants to try this https://www.instructables.com/100-3D-Printed-Linear-Snap-Action-Mechanism/
If you want a single piece part with this function, but without the need for assembly, you can look at compliant bistable mechanisms. These work just like this, but are more print in place. There are a lot of designs out there on the stl sharing websites. On the other hand, those might be more prone to fatigue than this one is, and for sure require more real-estate.
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