What is this thing?

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What is the fastener? (infosec.pub)

submitted 1 day ago by j4k3@piefed.world to c/whatisthisthing@lemmy.world

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Question is directed towards the engineers and machinists here. I think this is primarily a system designed to keep the clamping faces parallel, and perhaps there is some kind of bushing or shoulder bolt.

more context

I know a typical screw and nut in a pair of scissors will not align the blades well enough. I want to understand what kinds of hand finishing processes might be used to remedy the alignment problem. Like is this pictured example using a wave or crush washer to compensate for the alignment variation induced by the thread helix and pitch clearance, or something else likely going on? Does this kind of fastener have a name? Is there a more general variant with wrench flats on both sides or does this design typically require a more involved tooling to create?

In other words I want to have an abstract understanding of the entry point, nuances of application, and investment required to incorporate the design into other DIY type projects. For (a rough) instance, I have run into similar issues with the alignment of optics such as with image sensors.

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[–] j4k3@lemmy.world 5 points 1 day ago (1 children)

The professional hair stylist's scissors have the most wild variation. The tension is adjustable using the little tool spanner against the cross dimples. The wild part is that there are detents to how it tightens and does not feel at all linear. The detents are counted and each feels the same. The mechanism feels strange, like something one might expect in a pocket watch, not scissors.

[–] dual_sport_dork@lemmy.world 1 points 1 day ago

Those stylist's scissors are something I don't have any personal experience with, largely because in order to be equipped to manage hair it probably helps to have hair in the first place. The looks of that setup are almost certainly what the pivot assemblies in lesser scissors are aping, but in a less functional manner. Do you figure the ruffles in the edges of the spacer washers are what's providing that detent?

There ought to be a spring somewhere in the stack of hardware which looks and acts like a split lock washer, and that's what provides the motive force to keep the head of the bolt and/or back face of the nut in its place in its detents.