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Unread 18-08-2013, 02:53
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Re: CNC Router vs 3D Printer

Quote:
Originally Posted by EricH View Post
You're not really up on what 3D printing is currently used for in the real world, are you?

First, let me set something straight: "3D printing" can refer to any one of 5 processes. Yes, 5--FDM, SLS, DLD, ULA, and Objet are the acronyms. At least 2 of those 5 can print metal--I've seen them, I've handled the parts they've produced (Selective Laser Sintering and Direct Laser Deposition). 4/5 processes have very expensive machines, think 6-7 figures for the price tag, per machine. I know for a fact that at least a couple of those 4 can produce parts that will take anything you can reasonably throw at them--otherwise, the aerospace industry would throw them out and do something else. It might take a couple of days or so--but if you're comparing to several weeks, the 3D printer is downright fast--and it can do some things that would be VERY difficult to do on any other machine. (Trust me, I walk by my company's SLS unit every day--it's got some fun stuff in the window, but the machinists would freak out if it was handed to them to build.)

What you're talking about is one specific type of 3D printing. The 5th process won't work with metal, but because it doesn't use a laser (the other 4 do) it can be made relatively cheaply and sold to just about anybody. This process, which is known as FDM (Fused Deposition Molding, or something of that nature), is what most people will think of when you mention a 3D printer. It's basically a hot glue gun, only with plastic.

This process is, shall we say, under iteration. The thing about most of the users, at least of the RepRap model types, is that they will monkey around with build parameters if they can to get the best result they can. Some companies are playing around with different materials to see if they can get something better than current. I've seen several robot teams with 3D printed parts--I believe 207 printed wheels for their robot a year or two ago, with excellent results, though I don't recall what process they used.
You're right, I was referring to that type of 3D printing. We've got an early model MakerBot, and I've played around with parts off other machines too. That process in specific is very weak in my experience, because you're left with a bunch of layers weakly joined together, like a wood grain. We've made a few sensor mounts and stuff like that, but they're fairly inaccurate and shatter into layers very easily. As far as I know, there's no 3D printer within an average teams budget that doesn't use this process, so my comments were mainly in regard to printers of that type.

I've also gotten some stuff printed online through an SLS process, and it was quite weak too. Instead of layers being fused together, it was grains. I was very pleased though with a part I ordered cast in silver from a 3D printed mold (of course, I can't think of any reason a team would need to make something like that). I've never handled metal SLS parts, but I'd imagine that they'd suffer from weakness in the same way that SLS plastics would, because they're still composed of fused grains.

I have heard hype about 3D printed titanium or aluminum through SLS, but for the moment I'm inclined to believe that this is has yet to break though to traditional manufacturing or even mainstream prototyping. We're certainly not 3D printing replacement car parts yet. I'm very interested to hear that aerospace companies are making parts through SLS, but I suppose that with the kind of performance they'd require, they could afford to be an early adopter.

Maybe by the time I'm out of college, well be seeing cheap metal 3D printers in the wild. At that point, I'd become very interested. However, I think we're still a little bit before the time when 3D printing can really break through into the mainstream.
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