MX3D is to 3D-print a steel bridge over water in Amsterdam | Hacker News Reader

MX3D is to 3D-print a steel bridge over water in Amsterdam

phys.org

26 pointsdnetesn11 comments

Here's the actual process.[1] It's not clear if the video has been sped up.

The product quality seems comparable to rebar. Making a pedestrian bridge out of that stuff is a stunt, but it could be useful for making rebar reinforcing over which concrete is then poured. This would be useful for complex concrete forms.

[1] https://www.youtube.com/watch?v=NFF0QQIQDXE

Why "comparable to rebar"? Are you talking about surface finish, or material properties (which I, at least, am more interested in)? I normally think of arc-welding-deposited steel as "comparable to an arc furnace", i.e. very high quality. Could be that they're not using enough gas or something, and so end up with oxidation at the surface and possibly within the material; I'd like to see more detail to be sure.

I'd like to see more detail too. The video looks like they're tack-welding BB-sized pellets together.

It looks like most of the printing is sped up. At the end of the video, when the guy closes the door, there's a wait period of about five seconds between two pellets.

https://youtu.be/NFF0QQIQDXE?t=57s

Definitely sped up. If you read to the very end of the article, you'll find that the actual bridge is scheduled to take two months to complete. That's a long way from practical for a small footbridge. If they can't increase the speed by a few orders of magnitude, this technology will be a lot less usedful than they're trying to make it look.

There's a photo and a video of two different bridges in different locations, both about halfway through construction. If you read to the very end of the article, though, they don't plan to start construction until 2017, and they haven't even finalized the location yet. Also, it's expected to take two months of continuous operation to complete.

Seems like they're deceptively frontloading the interesting stuff to drive traffic.

If you look at the various elements of a 3D printer--filament/material, print head, print arm, bed, position control, material transformation model (e.g. fusing, sintering, curing/hardening, ...) they are innovating in a couple of dimensions at once. The idea of transporting the printer to the job site and not being constrained to a small volume by print head and arm seems to offer a lot of possibilities.

I think this would only be useful for robot/3D printer to do the fiddly bits of the bridge that are unique to that particular location (either end). Surely 95% of the bridge is cheaper to make in a factory some place?

A fair point, if you have modular construction with redundancy you can replace "factory parts" that break/rust/fail. I wonder what the repair process looks like for a bridge or other structure that's "printed out of the box" (on site).

You know what would be really cool? Something like this on the Moon or Mars. I bet you could get some really wild structures in a low-gravity environment.

That's a cool idea. They do it using robot controlled arc welders with welding wire fed in.

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