Thrifty Alternatives ..Building Foam Campers

[kudzu]

Please can I use this idea, too? Please, please, pretty please! I forgot about using arches for strength. That would really help.

http://www.tnttt.com/gallery/image_page.php?album_id=1860&image_id=86924

[GPW]

K’ It’s All there for Anybody that can use it ... Don’t even have to ask , just post pics of your build ...

[ghcoe]

Is there a consensus on who has the best canvas deals ???

HD has 9'x12' 12oz. canvas drop cloths for $31.39 and 11'x14' 8oz. canvas drop cloths for $30.49, local price. Just a thought.

[GPW]

Thanks George , like everyone else , I’m concerned with the seams , and would rather just plain canvas .. Looking around now for the best deal ...

[ghcoe]

Thanks George , like everyone else , I’m concerned with the seams , and would rather just plain canvas .. Looking around now for the best deal ...

Yes, I was too. Could not open the package, but as best as I could tell I believe most just had the edge seams. When the time comes I am thinking of puchasing a few, open them up carefully, and return the ones that have seams. Unless they all have seams then it will be a bust.

[GPW]

Just had a thought ... yes, just the one... Bamboo nails !!! We’ve been using common Bamboo skewers for many years now assembling foamie’ planes ... It should work fine for Foamie’ trailers too ... When joining sheets of foam , or adding on foam to foam , just add the glue , stick some skewers in and cut off the protruding part ... once dry just leave them there ... just like nails , except once passed through a layer of glue , they don’t come out ... regular nails won’t work .... screws either ... but these will ..
A pack of Bamboo skewers from the grocery cost a buck , providing lots of “nails" for most any foam joining .

Ps. for heavy duty “nailing” , Bamboo chopsticks work ... just another Thrifty Alternative ...


George , as has been said before , the seams properly placed could become part of the design ... all depends where they fall out on the tarp , and on the trailer ...

[kudzu]

What is the easiest, effective & low cost means of gluing foam to foam? Are people use Gripper effectively? Is there something else besides Gorilla Glue I could use? Though GG is great for wood, GG & I don't play well together.

There are a couple possible sources of cheap blue or pink foam within a reasonable drive of me. One has 4'x8'x1.5" foam for $10/sheet which I believe is good enough for my first project but may need to be doubled in some spots. Another has 2'x8'x1" foam for $1.50/sheet. Though much more labor intensive it could be glued up to the equivalent of a 4'x8'x2" sheet for $6.00 plus cost of glue. The 2'x8'x1" would work out cheapest, if you exclude labor costs, & is closer to me but would it really be worth it overall? Or should I get some of each?

BTW, the foam is going to be a 50th b'day gift from my BF. How many women want that? And during the camper construction I'll end up using my table saw, a gift from several years back. I am not your standard issue girlfriend but at least I can often do my own repairs.

[Mary C]

GPW, you could use an icepick to get the skewers, started, too much pressure on them to start ....didn't someone use them before or was I dreaming again?

Mary C.

[Wobbly Wheels]

I've been using them ever since someone else suggested it. If you twist them in, you don't need to start a hole, though an icepick should certainly do the job, Mary. I've been pulling them out rather than just leaving them in so I don't have a hard spot when I'm sanding. Leave lots sticking out to grab onto because they are tougher to pull out than to push in, especially if they get wet.

What is the easiest, effective & low cost means of gluing foam to foam?

Once the sheets are pinned together with skewers, I've been using canned foam. It's PU-based, just like GG but it's about the same density as the foam once it expands, so it sands with leaving hard or high spots. Works great and it's cheap !

I bevel the edges to be joined to create a V that I back fill with foam. Go slow and keep a really light touch on the trigger and you can mete out a little at a time. Afterward, you can clean the tube and valve by rinsing with acetone - I've kept part cans for months that way. I keep the acetone in a bottle from contact lens solution: it gives me a fine stream and I can use only a few drops where I need to so I use WAY less of the stuff. Don't forget your PPE.

Here's what the bevel looks like:


Foamed and sanded but not yet glassed. It'll get a skim of thickened epoxy to fill the pores as well - you can see that in the adjacent joints.

[kudzu]

WW, that looks great. Thanks for the explanation! Do you bevel the edges just to increase surface area or just to create a V that makes it easier to apply the foam adhesive. So is that Great Stuff or something else? Yours looks so good & the reports of easy sanding make me want to do that rather than the Locktite PL300 I was thinking of for the edges.

What tool did you use to make your bevels? (OK, maybe I should go back & reread your build thread like I meant to the other night.) I've got the table saw, a little circular trim saw & the handy-dandy electric carving knife. But was thinking of trying the sharpened edge of a putty knife first as it seems not so messy.

So there is still the question of gluing two 1" layers of foam together. Can't imagine using the canned foam spray for that but maybe I'm not imaginative enough? That's the part I was wondering if Gripper would work. Do you think?

[Mary C]

WW, I knew someone was using the skewers and you are using the GS foam too, WOW I am impressed. You are doing a great job. I was referring to when you put the canvas on the outside using skewers making a hole with an icepick I was thinking the difficulty of pushing it thru the canvas. I imagine it is easy to get them into the foam. Does the acetone melt plastic? I understand why to use the dropper bottle like you said but I just thought it would melt the plastic.

Mary C.

[Wobbly Wheels]

Thx kudzu, I appreciate that. I just used an angle grinder with a (60G I think?) sanding disc for the bevels. And yeah, it's for more surface area. A bevel also means that any over expansion won't try to push the panels apart and it allows me to make a nice, fair joint on the outside because those two glass edges are almost touching.
Gotta be careful though: the grinder doesn't even see the foam so you can make big mistakes really quickly !

That said, I was also going through a layer of glass. With just foam, a sanding block ought to work great.
An electric carving knife ought to work too. I've been meaning to grab one from the thrift store to try since they apparently work pretty well. For gluing flat panels, one could use the GS foam and quickly spread it with a disposable notched putty knife before it started to expand, then get a bunch of weight on it to keep the expansion even...but the Gripper sounds like a better idea for all that surface area. I haven't needed to bond sheets together that way, but I've been pretty happy with the latex contact cement I used to bond Formica to the foam.

Thx for the compliment Mary.
I just use the acetone to clean out the can of GS so the foam residue doesn't harden in the valve stem. I leave a drop of it sitting on the valve and put the (cleaned) tube back on. It dissolves the GS on contact and it will melt styrofoam too, but the plastic of the valve and stem aren't affected by it.
I didn't get that you're pushing skewers through the canvas. Yeah, the ice pick sounds like a great idea . The bamboo is kind of 'hairy' so there's a lot of drag when you go to push it in - even just poking the canvas to get it started ought to be a big help.

[KCStudly]

Has anyone done a large scale test (say, greater than 1 ft square) of foam laminated (glued flat to flat) using the Grabber/Gripper?

Mary, I thought you were using it to test butt joints (edge to edge). Did you do any test with the foam flat to flat? Any test with bigger pieces?

Early on there were concerns that large surface areas of foam to foam would have trouble drying/curing due to a lack of exposure to air.

Some people even had problems gluing wood to foam with wood glue.

In my experimentation I found that the wood to foam was not a problem so long as the glue was kept to a minimum spread very evenly (rolled on) and thus the wood had the capacity to absorb the small amount of moisture in the glue (or at least that is my theory… the theory that I was lead to believe from info I read here on the forum).

I’m not sure that it would be the same case with foam to foam. IIRC, Mary’s experiment was edge to edge so there may have been enough air exposure for that to have worked, but maybe not on a larger panel. I am assuming that the Grabber/Gripper is water based.

I would be leery of trying the GS on such large panels (call me a scaredy cat), and I wonder how much of WW’s success with that method comes from his advanced experience with glass fiber and resin/epoxy work. I guess I might have to give it a try though, since I plan on laminating two layers of 3/4 thk foam to make the roof and hatch on TPCE.

[kudzu]

KC, you've brought up a concern of mine & that's why I was asking about Gripper. Am embarrassed to say I'm only up to about pg 150 of this thread so have a long way to go. Yet there were a few hints in other threads that maybe some folks were using Gripper that way. I guess I could just bite the bullet, get the uber cheap 1" & use GG with the vacuum method. We know GG can work for laminating foam to foam... right? That's really what I'm fearing. Had planned to use the vacuum method to apply the inner plywood skin. Hadn't counted on doing it for that much foam. The price difference may not make it worth that effort. Maybe, just maybe, my time is worth more than that.

OK, I think I'll get some of the 4'x2'x1" but plan on getting enough 4'x8'x1.5" for the main body of the camper. It seems others are using 2" thick foam but I really think for such a small camper with a plywood inner skin the 1.5" should be fine. Please, someone correct me if I'm wrong.

[Wobbly Wheels]

KC, I haven't tried troweling out GS myself - I haven't had to deal with bonding flat panels together. It was a suggestion should someone be really set on using GS for laminating panels.
The low cost vs GG is a big advantage to figuring out how to make it work...but IMHO there are better ways to do that job. I've got a big jar of latex contact cement that I'm using for the little bit of flat panel bonding I'm doing.
Are you not going with the 30NF on yours ?

Missed this in kudzu's post the first time through:

...the Locktite PL300 I was thinking of for the edges.

I had a hard time with PL300 when I was doing the floor SIP. Maybe mine was just old stock or something, but it came out of the tube pliable enough but not really tacky at all so the bead wouldn't stay stuck. Warming it helped some, but it didn't leave me feeling warm and fuzzy about the bond if it wouldn't even tack up. I tried troweling the stuff too but it just rolled around and made a mess. Of course, it stuck to my hair and skin just fine !!!

For big panels, I think a latex contact cement is the way to go. The glue is dry before the panels go together so that 'sealed cure' isn't a problem.
It goes on as a thin liquid so it would key to sanded foam really well - probably about as good a mechanical bond as one could get on foam.

I made up some test panels a while ago, details are in my build thread somewhere. They are roughly a square foot and have a piece of 1/8" doorskin glued to 1" foam and a piece of formica glued to the ply. The glue was latex contact cement. For kicks and giggles, I just went and peeled one apart. Peeling isn't a failure mode I would really expect to see but the results still give me confidence that it's the right material for the job. YMMV and all that.

To prove that it did indeed happen:


The formica was easier to separate from the ply than the ply was from the foam but I was peeling it from the corner so that's to be expected.


You can imagine how much 'spring' the cement is resisting here. The white tip of my finger shows how much force is there - any more than that and the peeling continued.



It's interesting that where the foam failed was in a ring where the base of the paint can was that had the weights on top of it. If one were to evenly weight (vac bag?) the panel, it all ought to look like that. I'm about to start the curb side seatbox and this is how I'll be bonding the foam to the 1/4" ply top, except that I think I'll probably bag the panels rather than rolling them.

Of course, none of this addresses a purely foam-foam bond but, because contact is a dry adhesive, it ought to work fine....
'Schmaybe' ?