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This looks incredibly expensive with a lot of touch labor. The surface is incredibly gnarly due to being basically made entirely of welds. You'd want to grind t

This looks incredibly expensive with a lot of touch labor. The surface is incredibly gnarly due to being basically made entirely of welds. You'd want to grind that puppy smooth on the railings, etc. One thing that I think is finally entering the mainstream is that 3D printing is actually a MUCH more labor-intensive process than typical mass production techniques.

rtkwe 8y ago
A lot of that work could also be automated though if they wanted. There are machines out there today for smaller parts that will use wire deposition like this to build the bulk rough outline of the part then machine away the rough outer layer for a precision part. Leaving it rough though I think is an intentional choice part of showing off the materials and processes used instead of hiding it. In reality I bet the surface isn't much worse than an unsmoothed stone or concrete.
- Robotbeat 8y ago
  > There are machines out there today for smaller parts that will use wire deposition like this to build the bulk rough outline of the part then machine away the rough outer layer for a precision part. Right, so all you're really saving is the first rough cut, which is normally pretty fast anyway. (And the chips can be recycled.) But now you also have to live with the material properties of welds, instead of a high quality, grain-oriented piece of forging stock. And you also have to move the part from one machine to another, then re-register it (dial it in to make sure the build is oriented correctly in the CNC machine's coordinate system). Not as bad for the hybrid machines which can do both operations, but still not great. Back to this bridge: Without post-processing by grinding/sanding/smoothing, you're reducing the material strength due to increased localized stress concentrations. This doesn't matter much in stiffness-dominated structures, but significantly reduces the performance for strength-dominated structures and structures which experience a lot of cyclical loading. I just don't think this is terribly scalable. Neat art project, though. EDIT:If you want to automate things, I think it probably makes more sense to automate using more conventional building methods... Cut standard beams to size, place and weld automagically, etc. It'd be much faster..... Like this: https://www.youtube.com/watch?v=rD9__jheNLg https://www.youtube.com/watch?v=rD9__jheNLg
  - rtkwe 8y ago
    You don't have the move machines actually, as of about 3 years ago there are machines that'll do both in a single machine. [0] On top of that though moving from one machine to another really isn't the end of the world especially if you're able to setup the process right, like putting all the 3D printed parts onto a standard sized base plate that you can easily index off of. By bulk rough outline I mean they're basically just machining off the outer millimeter at most to smooth out the surface. It actually can save a lot of material as the size of the part increases because unless you're taking cast/forged pieces then milling them down to tighter tolerances the initial work piece will be the smallest bounding cube/rectangle or cylinder that'll fit the part which for some things is a LOT of waste. And yeah they will be slightly weaker than the same piece made out of a forged piece but that can be mitigated by part design and some annealing either after the milling or between printing and machining. [0] https://www.youtube.com/watch?v=oaIOrQi2HLM https://www.youtube.com/watch?v=oaIOrQi2HLM
anon_cow1111 8y ago
The last time I bought welding wire it was 3-4 dollars/pound for cheap flux core stuff, so I can't imagine how much this cost to 'print'. Most metal printers seem to work in a box full of helium/argon, but in this case they were just venting the shielding gas and probably using several times more than necessary.
geezerjay 8y ago
> This looks incredibly expensive with a lot of touch labor. This isn't as much as a bridge as it is a monument.
westbywest 8y ago
Likewise, I'm curious about the energy consumption of fabricating structures of this size (and greater) via laser sintering, when compared to conventional techniques of casting i-beams and welding only at the joints. The power required to effectively melt each cubic millimeter inside the structure, and also to position the robot arm throughout, doesn't look like it would be streamlined much if done at scale.
amelius 8y ago
> One thing that I think is finally entering the mainstream is that 3D printing is actually a MUCH more labor-intensive process than typical mass production techniques. I suppose you could 3D-print a mold, and from there do cheap production.
zeta0134 8y ago
The amount of time investment is really surprising coming into it, even as a hobby developer. The media portrayal seems to imply that you download a model, press a button, and out pops this perfectly printed part hot off the bed. The reality is more like 1. Calibrate the Z-axis again because that end-stop is glitchy 2. Apply some sort of adhesive to the print surface 3. Print with support (wait 5-20 hours) and hope nothing goes terribly wrong causing you to start over at step 1 4. Carefully remove the support material, hope the delicate bits of the part don't snap off in the process, if so start over at step 2 5. Sand, polish, and generally clean the part That's just for my hobby printer making, let's not mince any words, rather low quality prototype parts and figurines. I can't imagine the complexity that goes into printing these huge structures with production quality requirements. It's impressive, and I'm sure they're making the most of the tech since it can accomplish certain things that would be quite difficult in other mediums (the embedded sensors seem like such an awesome idea) but the time investment seems like it would certainly be quite high. Other than the coolness factor, I'm not sure it's more efficient than ordinary construction techniques, but I'm also just a hobbyist with a desk printer; I'm sure the folks actually working in that industry have much better insight.
- lozaning 8y ago
  >The media portrayal seems to imply that you download a model, press a button, and out pops this perfectly printed part hot off the bed I happily do exactly this all day with my several year old Makerbot. I print in 3D just about as reliably as I print something with ink on paper.
module0000 8y ago
Every day folks have no idea how much of welding actually consists of grinding. It's always fun when you encounter spatter/beads on a weld to ask the person you are with(assuming they are not and never have been a welder) what they think all those little beads are.... The most common answer I get is "it looks like balls of paint". There is a huge disconnect between how people think things are made, and reality.

rtkwe 8y ago

A lot of that work could also be automated though if they wanted. There are machines out there today for smaller parts that will use wire deposition like this to build the bulk rough outline of the part then machine away the rough outer layer for a precision part. Leaving it rough though I think is an intentional choice part of showing off the materials and processes used instead of hiding it. In reality I bet the surface isn't much worse than an unsmoothed stone or concrete.

Robotbeat 8y ago
> There are machines out there today for smaller parts that will use wire deposition like this to build the bulk rough outline of the part then machine away the rough outer layer for a precision part. Right, so all you're really saving is the first rough cut, which is normally pretty fast anyway. (And the chips can be recycled.) But now you also have to live with the material properties of welds, instead of a high quality, grain-oriented piece of forging stock. And you also have to move the part from one machine to another, then re-register it (dial it in to make sure the build is oriented correctly in the CNC machine's coordinate system). Not as bad for the hybrid machines which can do both operations, but still not great. Back to this bridge: Without post-processing by grinding/sanding/smoothing, you're reducing the material strength due to increased localized stress concentrations. This doesn't matter much in stiffness-dominated structures, but significantly reduces the performance for strength-dominated structures and structures which experience a lot of cyclical loading. I just don't think this is terribly scalable. Neat art project, though. EDIT:If you want to automate things, I think it probably makes more sense to automate using more conventional building methods... Cut standard beams to size, place and weld automagically, etc. It'd be much faster..... Like this: https://www.youtube.com/watch?v=rD9__jheNLg https://www.youtube.com/watch?v=rD9__jheNLg
- rtkwe 8y ago
  You don't have the move machines actually, as of about 3 years ago there are machines that'll do both in a single machine. [0] On top of that though moving from one machine to another really isn't the end of the world especially if you're able to setup the process right, like putting all the 3D printed parts onto a standard sized base plate that you can easily index off of. By bulk rough outline I mean they're basically just machining off the outer millimeter at most to smooth out the surface. It actually can save a lot of material as the size of the part increases because unless you're taking cast/forged pieces then milling them down to tighter tolerances the initial work piece will be the smallest bounding cube/rectangle or cylinder that'll fit the part which for some things is a LOT of waste. And yeah they will be slightly weaker than the same piece made out of a forged piece but that can be mitigated by part design and some annealing either after the milling or between printing and machining. [0] https://www.youtube.com/watch?v=oaIOrQi2HLM https://www.youtube.com/watch?v=oaIOrQi2HLM

anon_cow1111 8y ago

The last time I bought welding wire it was 3-4 dollars/pound for cheap flux core stuff, so I can't imagine how much this cost to 'print'. Most metal printers seem to work in a box full of helium/argon, but in this case they were just venting the shielding gas and probably using several times more than necessary.

geezerjay 8y ago

> This looks incredibly expensive with a lot of touch labor. This isn't as much as a bridge as it is a monument.

westbywest 8y ago

Likewise, I'm curious about the energy consumption of fabricating structures of this size (and greater) via laser sintering, when compared to conventional techniques of casting i-beams and welding only at the joints. The power required to effectively melt each cubic millimeter inside the structure, and also to position the robot arm throughout, doesn't look like it would be streamlined much if done at scale.

amelius 8y ago

> One thing that I think is finally entering the mainstream is that 3D printing is actually a MUCH more labor-intensive process than typical mass production techniques. I suppose you could 3D-print a mold, and from there do cheap production.

zeta0134 8y ago

The amount of time investment is really surprising coming into it, even as a hobby developer. The media portrayal seems to imply that you download a model, press a button, and out pops this perfectly printed part hot off the bed. The reality is more like 1. Calibrate the Z-axis again because that end-stop is glitchy 2. Apply some sort of adhesive to the print surface 3. Print with support (wait 5-20 hours) and hope nothing goes terribly wrong causing you to start over at step 1 4. Carefully remove the support material, hope the delicate bits of the part don't snap off in the process, if so start over at step 2 5. Sand, polish, and generally clean the part That's just for my hobby printer making, let's not mince any words, rather low quality prototype parts and figurines. I can't imagine the complexity that goes into printing these huge structures with production quality requirements. It's impressive, and I'm sure they're making the most of the tech since it can accomplish certain things that would be quite difficult in other mediums (the embedded sensors seem like such an awesome idea) but the time investment seems like it would certainly be quite high. Other than the coolness factor, I'm not sure it's more efficient than ordinary construction techniques, but I'm also just a hobbyist with a desk printer; I'm sure the folks actually working in that industry have much better insight.

lozaning 8y ago
>The media portrayal seems to imply that you download a model, press a button, and out pops this perfectly printed part hot off the bed I happily do exactly this all day with my several year old Makerbot. I print in 3D just about as reliably as I print something with ink on paper.

module0000 8y ago

Every day folks have no idea how much of welding actually consists of grinding. It's always fun when you encounter spatter/beads on a weld to ask the person you are with(assuming they are not and never have been a welder) what they think all those little beads are.... The most common answer I get is "it looks like balls of paint". There is a huge disconnect between how people think things are made, and reality.