[Blabber] DLP based UV photopolymer 3D printer

Peter Shenkin shenkin at gmail.com
Mon Mar 12 15:07:34 EDT 2012


I'm having trouble grokking the diagram. When the UV light shines through
the vat of polymer, why doesn't the whole vat polymerize, rather than just
the layer in contact with the growing object being raised from the vat?

I seem to recall that the original stereolithography devices that started
appearing in the '80s held the stage just below the surface of the liquid.
The UV laser was focused from above, and polymerized just the thin layer at
the top. Then the stage would lower a bit into the vat, exposing a new thin
layer of liquid polymer at the top, which would then be polymerized by the
action of the laser, and so on.

That is my recollection. I am guessing that the design in the link is
correct, and there is something I am missing. If anyone can (ahem)
illuminate the way the depicted design works, please speak up.

In any event, the ability to actually do STL (STereoLithography) would be a
great advance, in both resolution and capability, over the Makerbot and
RepRap machines -- not only from the point of view of resolution, but also
because overhang is rarely, if ever, a problem that one has to design
around. For instance, my iPod wire manager (
http://www.thingiverse.com/thing:16564) could be printed as a single piece
on such a device -- or at least, the type of device I recall. (Until I
understand this design better, I'm not sure the same advantage accrues.)

Also, at $40 a liter, building an object is going to cost quite a bit more
than devices that melt and extrude a thread of polymer, particularly if one
cannot save the unpolymerized liquid for later use.


On Mon, Mar 12, 2012 at 2:28 PM, Guan Yang <guan at yang.dk> wrote:

> We need to build one of these!
> http://code.google.com/p/lemoncurry/wiki/main
> _______________________________________________
> Blabber mailing list
> Blabber at hackmanhattan.danielpacker.org
> http://hackmanhattan.danielpacker.org/listinfo/blabber
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