Teardrops n Tiny Travel Trailers

Foam , it’s such a wonderful material for camper making .... we’ve been all through that so no use going there anymore . One of the things that makes our campers not only attractive , but Strong is the use of curved surfaces ... Curved , skinned foam is even Stronger by it’s very nature than the flat sheets ... by a lot too ... So far it’s not been so easy to curve foam surfaces , by using the kerf cuts ... which takes a lot of time , makes a huge Mess,and generally is not much fun to do , but looks Super when finished .

Having curved thinner foams in the past for model planes , I know it can be easily done by the heat method ... The idea is to get the area to be curved up to 190F degrees and the foam becomes bendable .. and stays that way forever. (until re-bent in the same manner)
I’ve thought a long time about how to bend 2” thick sheets of foam and how to heat up a large area uniformly ... And then it hit me ... I didn’t want to heat and bend large areas !!!... Thinking of how I’d bend a sheet of foam (4X8) .. it would usually be bent/curved in the long direction to allow for front caps , curved roofs, hatches, etc. But that’s Not really any good eh ... unless we’re only building 4’ wide trailers...
Now if we cut a foam sheet into 2’ (or less) wide X 8’ long sections, we can have easily bent/ formed pieces , heating only a 24” wide area (easy) making the bending easy , and allowing sections to be stacked together for Wider trailers ... The narrower pieces so much easier to handle , and the foam , being homogeneous material (no grain) easily glues together to form a larger structure , somewhat like Legos . A simple bending form could be built of wood scraps and such , wouldn’t be that big , and could be disassembled after using .. Heating could be done with a simple HF heat gun , or two (front and back at the same time ) which would be pretty quick and efficient .
Pictured below is a simple Proven type of jig that allows foam to be bent in marked increments allowing graceful curves over long distances.. Many ways to build it .. easy to use... and in 24” sections would be downright Quick and Easy ... for Two people ...
Ps. a temporary full form of the curvature could be built to allow for repeating as many identical sections as you want ..

Just like when this was first mentioned , (Foamie Trailers) naturally there were some doubters ... To those I can only say again “Watch and Learn” ...

Cutting the foam to a 2 ft wide piece makes it a more manageable piece. Heat it. Bend it, allow it cool then glue the pieces together. Should work. My worry is trying to heat the panel to the 190. I've tried the heat gun and no luck. Maybe steam bending like woodworkers do. Build a steam chamber add sufficient steam let it become pliable, set it against the form and allow to cool. That should work

I'm scratching my head on this problem. The good news, is that I don't need to bend foam (other than kerfing it and glueing it on a plywood ceiling). I'm just wondering how you get a 2" thick piece of insulation warmed up. I'd guess that it's just going to take a long time since conduction, convection, and radiation are not going to want to transfer heat in something that doesn't like to transfer heat.

I'd guess that the only way to do it using heat, is to put it in an oven –of some type– for a few hours at 190º and have it slump over a prefabbed mold and then allow it to cool.

My little pea-sized brain says it'd be easier to kerf it on a table saw, clamp it to the appropriate curve using bar clamps and lay in a piece of epoxy saturated fiberglass. The Burt Rutan's VeriEze/Quickie/Long-Eze homebuilt aircraft were all made from epoxy/fiberglass covered foam and had quite the following.

But it's an interesting problem.

TL

Hi guys

I had a thought on bending the foam.
What if..... you made a rectangle tube.... maybe 3'x 9' x 6" thick out of plywood.
Too kinda make a chamber with both ends open maybe?

Then take a salamander or propane heater something like a 20,000 btu heater.
Like you would use for temp heat in garage or in new construction in the winter sometimes
Then place the heater pointed at the open end of the chamber to blow the hot air though the chamber .

Place the foam in the chamber centered so the heat flows over all sides to heat the foam.

My other thought on heating the foam to temp is use halogen utility lights .
They get realy hot..... to hot to touch. Maybe put the foam on a couple of concrete blocks and put a few halogen's under the foam to heat

Oh ya one more thing.......DOINT BURN DOWN YOUR HOUSE TRYING THIS

Just a thought
Todd

OK, addressing one problem ... the heating . As we know there are two forces at play here, tension and compression , the outside of the curve wants to stretch , the inside wants to compress... the center is more or less neutral to those forces . The ideal would be some kind of oven or box to uniformly heat the foam sheets , but all that’s Impractical for only building one or two foamies...
The solution is to only heat a little area at a time , bend a little at a time . With a bending jig , one person on the front of the bend, one in the rear , two heat guns heating front and back on a strip only 3”X24” ... Only heating enough to soften the foam, to bend in a small increment .. many small increments make a gentle curve.

Having done this a Lot with thinner foams, In know it’d work on thicker ..
http://www.rcgroups.com/forums/showthre ... ndFoam+gpw

Experimenting will happen when I can gather the right materials to make a jig ... although not that large , it must be strong ...

This sounds like more work than just cutting kerfs, to be honest.

Schmaybe’ ??? Less messy for sure... As with everything else Foamie' ... this will be Tested...

I agree. Kerfing was a huge mess. HRH made me wear a painters suit and take it off outside while I was doing this task. I'm still finding little pink pellets everywhere in the garage. Who's gonna give it a go????

atahoekid wrote:I agree. Kerfing was a huge mess. HRH made me wear a painters suit and take it off outside while I was doing this task. I'm still finding little pink pellets everywhere in the garage. Who's gonna give it a go????

Everyone doesn't just strip naked in the garage after kerfing. Then roll their clothes wrong side out and drag them straight to the washer while on the way to the shower? Who knew?

LT, I had the most AWFUL mess after kerfing on the FS ... A literal “sea” of foam beads , tracked Everywhere .. After 6 months they mysteriously disappeared... (sunk into the grass) Heat bending would involve a couple of friemds , an afternoon of bending and a few cold ones ... What could be better ??? No mess to clean up ... just put the heat guns away ...

Just an idea from Down Under, why not layer up using multiple layers of 1/2 inch foam which bends readily. If each layer is glued up properly then I reckon the end result would be even stronger than the kerfed or heated methods.
Mike

Mike , that’s already been done... and does work !!! I was just trying another way ...

?
try putting your cloth on first
Gary

Gary, That’s It !!! Please tell us all the details ...