Cory Doctorow at 12:32 pm Mon, Nov 14, 2011
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Here's a great little video explaining laser-sintering, the process by which some 3D printers do their magic -- melting fine powders, bit by bit, into 3D shapes.
How Laser Sintering Works
This is a great introduction to laser sintering, and really to 3D printing in general.
Do you think god has a laser that can turn rock into bone? Cause this could explain all those dang fossils.
Time to be a pedant.
Sintering != melting. Sintering is driven by reduction in surface area (and hence surface excess energy). Sintering depends on an elevated temperatures to increase the rate of diffusion and rates of other processes. It does not involve bulk melting.
You can think of it as a process of fusing the powder particles together while they remain solid.
Thank you. Even I could follow and grasp. If anyone knows how long it took, just the ‘sintering’ process for that piece, lemme know.
: layer thickness varies, but each layer is somewhere from .004 inch to .006 inch per layer. Orientation affects part properties, too, so it may not be in the build area the “thinnest” way. Each layer can take (in a common machine, the 3D systems 2500+, for example) from 30 seconds to a minute, with dwell time for the powder to film-form.
dbcooper_o: some polymers go fully liquid in laser sintering, some don’t. Depends on the melt viscosity and properties of the polymer.
Okay – so that finished piece took_____?
it’s not strange for a build (in which there can be many parts, not necessarily just one large one) to take 24 to 36 hours — not counting part cleaning/prep time.
Lungs! Seems like the sort of thing that should require at least a cloth mask if not a full respirator.
That’s exactly what I was thinking — plastic dust can NOT be good for you…
much of it is inert — nylon, etc. Hazards are the same as dust from mowing the yard. (less inhaled dust is obviously better, and respirators are commonly used and should be.)
Ahem, your typical rigid SLS nylon material is glass filled, not pure nylon. There’s a lot of chemistry that goes into these materials, they’re not just “nylon” or “steel”. Point being, you don’t want to breath them in, probably more so than lawn clippings.
None of the RP materials (SLA, SLS, FDM) are particularly nice materials (some are carcinogens). Gloves and masks should be used while building them and also if you file or finish the parts later.
I wonder what other types of materials can be used in this application. Would it be possible to insert wiring or whatever between layers as something is built?
And holy crap that was a lot of powder and human interaction right?
Not really possible to insert things, as the chamber in which they’re being built is filled with inert gas, heated to about 275+degrees Fahrenheit, and the roller spreading the powder goes back and forth in rapid succession. The inert-gas-blanket is necessary to protect the powder from degradation.
Lots of powder, yes. 40+ kilos in a large build.
Thanks for this, there’s some nice detail in there about the process; my brother and I are looking into building one of these, mainly to see if we can (and then to print some sweet bike frames). Any more where this one came from?
Also, Holy Crap! Solar sintering in the desert. Crikey. http://vimeo.com/25401444
Great introduction. Anybody know if other powders could be used? For example aluminium or glass?
How long until there’s a near-consumer range product, I wonder.
I wonder how many 3D Holocats have been teased by one of these.
SLA resins — nasty, no doubt. FDM materials I’m not familiar with, but heated ABS doesn’t seem like a fun thing to be around. Most SLS materials, though, are pretty much inert from my experience. The nylon is inert. The glass beads that are used in glass-filled material are inert– small, sure, but harmful, no. I’m familiar with the materials used, and I understand the chemistry and all that behind them.
Either way — wear a mask and gloves when breaking out parts or loading the machine, sure. That said, much of it is inert material. (and there’s no need to wear a mask while running the SLS machine. There’s no contact with the material while the build is in progress. And yes, wear a mask when finishing/sanding on parts.
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