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Comment by mdorazio | Hacker News Reader

Does anyone know how the dovetails of the individual jaw pieces are machined on a curved surface? I can’t figure it out even using a 4 or 5 axis CNC.

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I must be missing the difficulty. It looks to me like you could turn those dovetails on a lathe. You cut them into round stock before sawing it in half and facing. The female dovetails are done directly on the OD of the round stock. For the male dovetails, it would require mounting the work offset (eg. on a faceplate); alternatively, you could do it more awkwardly on a mill with the tool offset in the spindle like a boring bar. Either way, it could be done with manual machines.

Exactly.. turned on lathe, millwork if not 5 axis, hardened, and then ground to finish.

The male dovetails might've been made with something resembling a hole saw, but with the teeth angled appropriately.

That's fine for the outer pieces, but the ones they mount into have dovetails on both inner crescents. I can't see how you could turn those on a lathe without some weird offset going on.

Well, yes, that's what you do. It's called eccentric turning. With that much of an offset, a normal chuck wouldn't work, you'd have to use a faceplate.

http://www.steves-workshop.co.uk/tips/lathetech/eccentrics/e...

That explains it! I didn't know about faceplates - thanks for the info.

>> For the male dovetails, it would require mounting the work offset (eg. on a faceplate)

Hand Tool Rescue restored one of these and he ends up having to rebuild some of the semicircle pieces. It's a fun watch!

https://www.youtube.com/watch?v=QBeOgGt_oWU

The way the little arms sorta appear to reach out while it tightens is kind of adorable.

Fractals always seem to have oddly biological looking behavior, for things made with such simple rules.

I don't actually know, but maybe electric discharge machining?

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