On Thu, Aug 7, 2014 at 12:08 PM, Bruce Johnson
<johnson@pharmacy.arizona.edu> wrote:
>
>
> This is a cool idea, basically a very large deltabot 3D printer.
>
> <http://en.wikipedia.org/wiki/Delta_robot>
>
>

Yeah, with the addition of the "auto set up" mode with wheels...

> A couple minor points:
>
> It is possible using a large fresnel lens and sunlight:
>
> <http://www.thisiscolossal.com/2011/06/markus-kayser-builds-a-solar-powered-3d-printer-that-prints-glass-from-sand-and-a-sun-powered-laser-cutter/>

Was inspiration for using sand
Wanted to use Frensel, but couldn't see way to avoid shadows with
larger print volume
Also mechanism to keep pointed at sun while moving through larger
volume _and_ support much large lens got way too yucky looking

>
> Second, this will require pretty pure sand; organic matter mixed in will weaken things pretty badly. There’s a reason that the solar sinter project above was done in the middle of a dune field...
>

I had this mental image of the hopper having a thing like a flour
sifter in the bottom, letting only sand-grain-sized things through.
Then a pre-cook mode, where a lower power laser ignites anything
organic as it goes through the tube into the storage bin the Spider
feeds from.
Probably another flour-sifter along the way too.

Also had thought of a "pebble box" - a collector for gravel-sized
things the flour sifter caught.
Then have a mode where they're fed in to the making, with the glass
flowing over them like mortar.