Hacker News Reader

Comment by tsmarsh | Hacker News Reader

After building my own printer from parts and realizing how hard it is to make something that can follow gcode accurately, repeatedly and quickly I’m still left wondering “How good is this hand?”

Most of the stuff I’ve printed or built has ended up being “ok”. A lot of that is that I’m not a meatspace engineer, or a pixie engineer, I’m a software engineer. So I’m very much on the learning curve of robotics... but there is a lot to learn. AvE talks a lot about industrial lego, and its true you can just bolt and solder stuff together and get a prototype, or a proof of concept, but getting that to a product is really hard.

So when we say that a kid has built an arm for his Dad, is that a cute story or a sign that the bar for this kind of technology has dropped to the point that a high school kid can build a useful product?

I suspect in this instance its a cute story. That or I really need to up my game.

View on HN

There's a pretty large community online 3D printing prosthetics, mainly the loosely affiliated community called enabling the future[0] and a nonprofit which sprung from them called Limbforge[1].

The printed prostheses are almost all body powered, which means they use some sort of harness to pull a cable with the closest extant joint on the arm, and those cables close the grip.

As body powered prostheses go, they're pretty good nowadays. They're still nowhere near the usefulness of say a BeBionic, but they cost tens of dollars instead of tens of thousands, so it's a reasonable trade-off.

Kids are the best use case by far though, because they grow out of their hands every year or two. When you can amortize the cost over years I think the high end devices are a much better choice, but if someone can't afford them or just doesn't want a prosthesis that badly the printed options are still a nice alternative.

[0]: http://enablingthefuture.org/ [1]: https://www.limbforge.org/

The ABC article seems a bit more informative: http://abcnews.go.com/US/teen-builds-baseball-throwing-prost...

This kid designed CAD models and printed two entirely different prosthetic arms: one to use a Switch controller one-handed (with the remaining good arm, obviously) and one for throwing a baseball. They clearly both serve their purpose pretty well. He's enabled at least two use cases that his dad was unable to do with his existing commercial prosthetic arm, so I'd say it's more than a 'cute story'.

Looks like they used an i3 Duplicator Plus which is a $350 machine. I have a near-identical model myself (non-plus version) and the prints are fine, though it can take a lot of fiddling/calibration to get there.

I mean, unless you have an incredibly high end printer nobody expects 3d printed parts to come out perfect. As far as I can tell, you pretty much always need to to some hand fitting afterwards. My part time job in highschool involved building robots (as in actually assembling them) for a small company, and as a result I feel comfortable claiming that anyone with access to CAD, and a machine shop can build a workable "robot".

Your instincts are right. Finished goods are the result of skilled work by many, many people.

Reply on news.ycombinator.com