Flexures, flextures, compliant mechanisms

August 26, 2020 6:33 PM

Fixtures that work because part of them is flexible.

Wood and bronze

Two takes on it from Amy Makes Stuff: A demo board flextures laser-cut from relatively soft thin material, plus a gripper picker upper, 7'; and a Hackaday lecture/demo, half an hour.

3D home printed ones, calling them compliant mechanisms -- choice of puns! "Single units that rely on elastic deformation in order to get their mechanical properties".

A professor of compliant mechanisms and some of his flextures; unexpected elephant

A waterjet used to make flextures for optics experimental prototypes (and other things) (one of Dan Gelbart's lectures, previously)

Can someone explain this waveguide with flexure?

I'm pretty sure the space straw is a flexture, especially when it clips closed

posted by clew (9 comments total)

Ooh, flexures! They're popular for space applications because sliding or rolling joints are so troublesome up there. My claim to not-very-much-fame is having helped with a flexy bit on Mars.
posted by Maxwell's demon at 10:43 PM on August 26, 2020 [9 favorites]

That's cool! Reminded me of some of the bits of SNES controllers seen in this teardown.
posted by BlackLeotardFront at 11:20 PM on August 26, 2020

a flexy bit on Mars

Rejected Bowie album name
posted by Greg_Ace at 11:52 PM on August 26, 2020 [3 favorites]

Nice, i meant to drop some compliant mechanisms / Larry Howell links in that thread a couple of months ago about cleverly designed but physically simple cybernetic mechanisms but didn't have the spoons.
posted by ver at 12:12 AM on August 27, 2020 [1 favorite]

I'm glad the Professor video was there so I didn't have to go looking for it. It was the first thing I thought about after watching the main video.

I'd assume the waveguide is self aligning because the flexing part reacts to the light in a way that if it's a bit off in one direction it bends the other. So even not being fixed in place and subject to strains and some accidental bump/vibration sending it out of alignment it instead is decoupled and will seek the alignment all by itself.
posted by zengargoyle at 1:57 AM on August 27, 2020

The humble rubber dome keyboard switch is, to my way of thinking, a little triumph of flexture engineering.
posted by flabdablet at 2:13 AM on August 27, 2020 [1 favorite]

she's made the worlds best fidget board. This was fascinating. "our cat" - whispers "one of us. one of us."
posted by FirstMateKate at 9:40 AM on August 27, 2020

I've got a soft spot for the Rolamite — not just that it's exactly the same age as me — because of its incredibly low friction.

One of my work's open-source switches uses a 3d printed flexure.
posted by scruss at 4:10 PM on August 27, 2020 [1 favorite]

Disney's research arm has a generator for compliant mechanisms to replace rigid ones that make a particular looped movement (like that of a wing in flight). It shows some of the weaknesses of compliant mechanisms, I think, in the constraints they have to add so that the material doesn't fail in the real world.

This starts, afaict, with something like their work on computationally finding gear assemblies that produce any loop movement, to make mechanical creatures move.

Vaucanson wept!
posted by clew at 11:25 AM on September 13, 2020 [1 favorite]