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Comment by mionhe | Hacker News Reader

Mold design is still difficult when the parts aren't dead simple. The software I've seen is okay with the simple stuff, but once you get even a little more complex you have to understand simultaneously how to design good parts for molding and how to design good molds, both of which are heavily dependent on the type of plastic you're using and the size of the press you have access to. Not to mention how to machine good molds from metal, which is a challenge all on its own due to surface finish and tolerance requirements (and weird geometry that makes the CAM choke...)

In other words, we're not really there yet to bring that activity into the hobby realm. But I hope that we're not too far away.

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They're little linkage parts, mostly flat.[1] Some of those holes are bearings. None of those parts are hard to make, but they need to be strong. They could be made by CNC machining, or in quantity by injection molding, or stamping. But tiny working parts in 3D printed PLA will be too flimsy for that hand to do much work.

Totally fixable problem. Then this hand can go to work.

If this thing catches on, someone might sell an upgrade kit with stronger parts. The designer is already considering a servo upgrade.

[1] https://github.com/pollen-robotics/AmazingHand/blob/main/ass...

I haven't looked too carefully, but I suspect those "needs to be strong" parts could mostly be cnc machined with an inexpensive hobby CNC like a 3020, from aluminiumn sheet/bar stock.

That's what I was thinking, too. All but one of those parts can be easily milled from flat plate. The yoke end is a bit harder, but yoke ends are cheap standard parts and there's probably an off the shelf solution. The ball joints they use are standard R/C car parts. Those are available in in a stronger form, nylon with a brass ball, for EUR 0.53.[1] It won't be hard to strengthen this design so it can do useful work.

[1] https://toni-clark-shop.com/Ball-Joint-for-M2-and-M3

Smiles from Detroit. I would look to press those parts, since most contact surfaces are potentially convex and variant-depth parts appear superfluous to requirements. With a shared punch and die you could pull the nest off a laser, press them all in parallel, and break them after the parallel press-forming. Should be cheaper than injection because the cycles can be faster, the material can be stronger, there's only one die, and the unload will be easier?

Yes. Here are very similar parts produced with a punch press.[1] In Silicon Valley. Or in China.[2]

This sort of thing is probably about $40,000 for the first part, $0.05 for each additional part. Designing and making the custom dies is expensive. Banging out the parts is cheap. Mass production works.

[1] https://www.petersenprecision.com/fine-blanking

[2] https://yonglihaomachinery.com/

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