Re: [rp-ml] Super Large RP or AF

From: O. Makai Smith <makai_at_digiplasty.com>
Date: Thu Jun 22 2006 - 20:48:02 EEST

That's one good way to go. I've seen some designs using urethanes.
Wish I could remember who the designer was, but it was an articulated
arm (crane scale) that could build domes around itself to form insulated
concrete structures.

As you suggest, secondary shaping operations could let the machine use a
fairly coarse extrusion (and it's hard to control self expanding
polyurethane foams because their expansion is so temp and mix
dependent). Isocyanates are kinda nasty too. The high quality rigid
ones are made with a blowing agent which might be worth thinking about.

Anyone know about how they make those starch "packing popcorn"? I
wonder what other "green" foams could be used. Mill enough foam and you
start wondering how big rice cakes come.

Makai

Charles Overy wrote:
> What about a super /FDM/Solidscape extruding metermixed rapidsetting
> urethane foam. A 2nd gantry/head net shapes the extrusion with cutters.
> (top and sides or, in a more advanced version, adds detail to the
> extrusion.)
>
> Charles
>
>
>
> Charles Overy : Director of Engineering
> lgm :: architectural visualization
> http://www.lgmmodel.com
> cwho@lgmmodel.com <mailto:cwho@lgmmodel.com>
> 970.827.5274
> 800 448 8808
>
>
>
>
>> -----Original Message-----
>> From: owner-rp-ml@rapid.lpt.fi [mailto:owner-rp-ml@rapid.lpt.fi]On
>> Behalf Of O. Makai Smith
>> Sent: Wednesday, June 21, 2006 2:48 PM
>> To: rp-ml@rapid.lpt.fi
>> Cc: John Brock; bo@midcoast.com
>> Subject: Re: [rp-ml] Super Large RP or AF
>>
>>
>> Hi John;
>> Right you are! We used primarily that method for making the MGM lion:
>>
>> http://www.kreysler.com/projects/mgmlion/lion.htm
>>
>> and other large figures we did awhile ago. Though we do very little
>> slicing now. The bear:
>>
>> http://www.kreysler.com/projects/Blue%20Bear/bluebear.htm
>>
>> was done using milling (of molds). The aligning/gluing introduces
>> enough slop (and takes so much time) that we tend towards milling out
>> the foam positives or molds directly (and segmenting them as necessary
>> to account for the complexity of form). Internal features, of course,
>> are not possible this way without some effort, but we have yet to build
>> a large enough additive machine to make our gantry mill obsolete!
>>
>> I'd like to though. I think the robotics is the easy part (maybe using
>> EMC for instance?):
>>
>> http://www.linuxcnc.org/
>>
>> But the build material, not so much. Berok's using fast-cure cement;
>> there are polyurethane foams. I am interested to hear about what
>> thoughts others have about materials to deposit (and also on control
>> systems, and mechanical platforms...I see a lot of gantries, but there
>> are many other ways to move the nozzle).
>>
>> Makai
>>
>> John Brock wrote:
>> >
>> > Hi Bo:
>> > For big stuff, think "subtractive" instead of "additive" RP. Your
>> model can be milled in slabs from 20# foam on a large gantry mill. The
>> sections can be pinned together, then lost detail re-carved, then filled
>> and sealed with Bondo and primer. This big model can be used as a plug
>> to make a mould. Then using the mould you can lay up as many as you
>> need in Fiberglass. This is how Disney Imagineering gets 25' tall
>> fiberglass Mickeys, etc.
>> >
>> > John Brock
>> >
>> >
>> >> Thanks good people, I really appreciated the update on capabilities
>> of rp
>> >> today... I must say I'm surprised no one seems headed in the
>> direction of
>> >> trade off towards low cost rp with low accuracy... Not that it is
>> easy. For
>> >> the price of a life size, high detail foam bovine, it seems I
>> actually built
>> >> a giant 60 ft or 20m snapping turtle with a garden inside: http://
>> >> www.midcoast.com/~bo/TurtleGarden.html . I'd still love to get work
>> on a
>> >> derrick supported rp system using concrete. I think much more must be
>> >> possible at a dollar per pound or a euro for a kilo range, at least
>> by use of
>> >> fire-wire cameras with renaissance-ciaro-scuro methods and concrete
>> batcher,
>> >> which i kind of used on the turtle... Turtle is mostly soils and
>> less 1$ US
>> >> per kilo when you subtract associated landscaping and 60+ meter
>> wetland I
>> >> personally dug and leveled for them with a mini excavator.)
>> >>
>> >> Bo
>> >> Atkinson
>> >>
>> >>
>> >>
>> >
>> >
>>
>>
>>
>
>
>
Received on Thu Jun 22 20:05:19 2006

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