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Re: Rolling wigwam /organic vardo/geodesic

PostPosted: Fri May 10, 2019 5:49 am
by GPW
Since we already proved that you can heat bend foam and it will stay that way ….. you could pre-bend sections of foam on a “form” and then just glue them together , then cover … We’ve been pushing around that idea for a while … :thinking:

“ I think skin on lashed frame maybe with a double fabric wall with foam injected between might be possible, Could be super light and strong.
“ …. yes it “should”, but injected foam doesn’t always expand the way you want it to ... :o Maybe between two forms to keep a specific shape ??? That would be super eh ??? Finished panels … :thumbsup:

Yes the Foamstream is just a half cylinder sitting on a wall with a rounded nose (the only real compound curve part ) … And Yes, we did have access to a CNC router , and we’d do it all over again if we had to … It worked so far ( 6 years now )

Now then , taking a note from the Tipi, Fabric stretched over a frame ( sounds like a Tent eh ? ) and with an inner liner to allow an air space in between ( insulation) , that idea could be applied to a trailer built “similarly” to an aircraft fuselage ( formers and stringers ) with an inner and outer skin … You could make the frame any shape you wanted that way … or even an EGG ;)

The problem is most of these methods would require a lot of labor … even just cutting saplings and bending them to shape as a frame would take a good bit of effort to get "just right" … :o Ther Old Timers steam bent Hickory or Ash to make Bows for their wagons … same process could be used for formers … Lots of possibilities … Could be Fun !!!

Re: Rolling wigwam /organic vardo/geodesic

PostPosted: Fri May 10, 2019 8:34 am
by John61CT
Exactly. Making up for lack of high tech tools with labor intensive time. If a once-off, incorporate the "form work" as greater-strength load bearing support. It's still going to be light AF.

PMF framing members perpendicular to the skin, tensile-reinforced over very light ply where needed.

Or tube profile, maybe electrical conduit? very cheap, and can be further strengthened & shape-fixed by filling with pourable higher-density foam - yes with careful temp/volume measurement to precisely control expansion.

_______
Man goes to see a shrink, "Doc, I just dunno, am I a Wigwam, or a Teepee?"

"Relax son, you're just two tents"

Re: Rolling wigwam /organic vardo/geodesic

PostPosted: Fri May 10, 2019 9:22 am
by VTSteve
Or you could use this free software from Carlson design. It is limited and geared toward boat design but it might work.
http://carlsondesign.com/projects/hull-designer/
Its been a while since I played with it but it will print out plotted curves and coordinates so that a form could be build without CNC.
I need to figure out how to install it again on this computer as its not a super easy install and can't remember if it will run on windows or mac.
But I remember it being pretty cool for free. Could be useful for plotting curves for cutting panels. Dealing with cutting "gores" is another thing though.
I define a gore as a triangular "v" cut in flat material that is used to get a material to wrap around a corner or compound curve. Using a fabric with some stretch might reduce the need for this somewhat.

Re: Rolling wigwam /organic vardo/geodesic

PostPosted: Fri May 10, 2019 9:33 am
by KCStudly
I love the woven basket idea for an inner skin. You could get all fancy and bind the edges around doors and window frames, etc. Glue or even stitch on a thin bed sheet or light canvas barrier ply and paint it so the foam doesn't ooze thru the weave; then spray foam. Or better yet, build a segmented negative mold, suspend the "basket" in the mold and pour foam in the gap. Or better yet, gel coat the mold; lay in some glass weave, then add basket and mold foam.

Still a lot of work material cost, but wouldn't that be a sweet interior treatment and water proof exterior! (Much easier to find some basket weave textured wall paper or bamboo mat and paste it on the inside of a plywood box.)

Re: Rolling wigwam /organic vardo/geodesic

PostPosted: Sun May 12, 2019 8:00 pm
by John61CT
Yes, masterful basket-weaving would make a gorgeous skin,

yes more practical inside, but imagine a clear urethane coated outer skin?

Nice and tight weave, backed with slightly darker canvas, impregnated with Gripper to make a semi-rigid mold.

Getting enough precision to have two layers with a consistent, say 3" gap to fill with poured foam would be pretty darn hard.

Maybe one day a laser-guided CNC-robot basketweaving machine!

Re: Rolling wigwam /organic vardo/geodesic

PostPosted: Sun May 12, 2019 8:02 pm
by John61CT
Maybe relevant, is coroplast cheaper than luan?

http://tnttt.com/viewtopic.php?t=71655

Re: Rolling wigwam /organic vardo/geodesic

PostPosted: Sun May 12, 2019 9:13 pm
by John61CT
From there, boat shrink-wrap material!

now there's a thought. . .

If nothing else would help make a cheap convex mold for the inside layer.

LDPE, nothing sticks to it (even Gripper? so self-releasing

1200 gauge is tough stuff, with a tight smooth /strong support structure underneath, should get tight and straight enough to require a minimum of fairing afterwards.

Re: Rolling wigwam /organic vardo/geodesic

PostPosted: Sun May 12, 2019 10:53 pm
by John61CT
VTSteve wrote:Or you could use this free software from Carlson design. It is limited and geared toward boat design but it might work.
http://carlsondesign.com/projects/hull-designer/
Very cool, thanks

> Dealing with cutting "gores" is another thing though. I define a gore as a triangular "v" cut in flat material that is used to get a material to wrap around a corner or compound curve.

Well not triangular. The parachute XLS outputs this curve for a semi-ellipsoid, similar to a flattened hemisphere, with a minor/major axis ratio of 0.707, 222cm diameter and made up of 48 gores.

Also an example from a kid's globe project.
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