Very light and no wood at all -- possible?

[Jack Olsen]

It seems like there should be a good way to control the amount dispensed in order to make the 3:1 or 4:1 expansion consistent and manageable. It's a shame they don't make a spray version. The construction adhesive doesn't expand. I don't know if that also means it's not polyurethane-based. It would definitely work for putting a layer of the corrugated plastic over the XPS foam for the interior. But for the bond between the aluminum composite panel and the XPS foam, I'd like a very strong bond -- since that would contribute a lot to the overall structural strength of the camper.

I was surprised by how well both Gorilla products worked on the corrugated plastic. I think the trick is to use plastic with the surface treatment already done. Another sample I have on hand has the more-slippery texture to it, which I suspect would resist just about any adhesive. (I'll test it to be sure, though.)

I've used Glidden Gripper with EPS foam and fiberglass cloth for another project, and it worked great. I also tested it as a foam adhesive, and it was great except when it had to fill gaps. I have no idea how it would work with the corrugated plastic, but since I've still got the better part of a gallon here, it will be easy to try out.

My biggest concern right now is finding the most effective way to bond the Aluminum Composite Panels to aluminum and to each other. That would take care of the main structural strength for the trailer.

[Pmullen503]

How about just riveting or screwing aluminum to aluminum joints for structural strength (you plan on aluminum angle for the outside corners right?) Maybe bed them in something like Sikkaflex 219?

Bonding foam and whatever you use for the interior surface wouldn't be so critical then.

[Jack Olsen]

At this point, I'm trying to figure out how to get the maximum possible strength for the structure. But yes, being a suspenders-and-belt guy, I'll also rivet the ends of each seam to prevent zipper-type failures.

Here's a little test I put together today. I bent some aluminum 3/4" square tubing into a simple curve.





Then I cut two small aluminum composite pieces to match the curve and did a quick-and-dirty job of putting the same curve into a flat 'roof' panel.



Then I assembled it with VHB tape. I used rivets at either end because the look-ma-no-tools curve I put into the composite panel wasn't very close to being correct.



Then I caulked the top with Dow 995 and added a two-layer corrugated plastic floor supported on the sides by some aluminum 1" angle stock. For the floor and its supports, I only used Gorilla Glue -- both to see how it would seep/foam out, and also so when I break this thing apart I can confirm that the Gorilla Glue bonds will fail before the VHB/Dow-995 bonds.

[Jack Olsen]

Here it is with an hour's cure time, the protective plastic taken off, and the fake matte aluminum cover. The aluminum cover material looks kind of strange here, but I think it will do better with polished aluminum or chrome trim.

It's not remotely square, but at these (admittedly-not-real-world) dimensions it feels extremely strong.



Next up is to decide if this basic structure (with foam and corrugated plastic inside to increase the walls' overall rigidity, and another layer of adhesive covered by trim on the outside edge) will be enough -- or if there's a way to improve it.

Any ideas or suggestions?

[aggie79]

Jack - thank you for all of the material testing! In some of my mind exercises I was thinking of a build that used ACM exterior over a plywood "frame". I found the manufacturer recommendation to be the same as you used here - VHB tape and structural silicone adhesive.

May I ask how you formed the curve in the ACM for the roof? The only sample of this material that I've handled was 3" x 3". It didn't seem that it would bend easily.

Take care,
Ton

[Jack Olsen]

It will be interesting to see how a full-size sheet does with bending. For this, I just took the ~6"x12" piece and rolled it back and forth over a piece of 2" plastic pipe. But that kind of forming tends to overbend it in the middle, where you have more mechanical advantage, and leave the ends too straight. For the full-size sheet, I've thought about making a 3-roll bender (or whatever it's called) as a cheap, one-time-use tool. The idea is the same as the bender I used to curve the aluminum tubing:



-- but my thinking was to see if I could get three 6-foot lengths of thick-walled PVC pipe and make an extended version for sheet stock where I could adapt a pair of C-clamps to apply pressure on the top roller to create a curve as I moved the material through it. Like this, but with a pocket-change budget instead of tens of thousands:



It would probably be possible to simply conform a full sheet to a frame like skinning with aluminum. But the ACP material has more rigidity and would probably keep wanting to spring back over time than 040 aluminum. I'd be more comfortable getting the roof to its correct shape before I broke out the VHB tape and made any of my subsequent mistakes permanent.

[M C Toyer]

Jack -

All good tips. Thanks.

Is your tubing bender one of the Harbor Freight models? Did you purchase the optional rollers for square tubing or use the standard. rounds?

On your corrugated plastic sheeting is it faced with aluminum on one side or both?

As for the home roller setup you would probably still get some flex with the pvc but I've made similar devices and inserted steel pipe and/or wood slats to stiffen.

You could probably get a small HVAC sheet metal shop to professionally roll to your specs pretty cheaply; maybe a six-pack and a sack of burgers or tacos at lunchtime.

M C

[Jack Olsen]

Is your tubing bender one of the Harbor Freight models? Did you purchase the optional rollers for square tubing or use the standard. rounds?

Yep. I got square dies for it, and also modified it to be powered by a HF pipe threader. It's a pretty affordable/effective combination.



I used it to bend a bunch of steel when I built my deck so it would have a pergola cover.

This was the hapless builder part-way through it. Maybe in over his head.



I had to come up with a way to raise the pergola top up so I could weld in the pillars that would hold it up.



But I got it worked out in the end:

On your corrugated plastic sheeting is it faced with aluminum on one side or both?

The aluminum-coated stuff I can afford has a polyethylene core, like foam core for art projects. Then I will probably also be using corrugated plastic with no covering on it. I would love to use the corrugated plastic with aluminum on both sides (I got a sample in the mail today), but it's more than twice the price of the thinner stuff.

As for the home roller setup you would probably still get some flex with the pvc but I've made similar devices and inserted steel pipe and/or wood slats to stiffen.

Yeah, I wanted to see how much bowing/deflection/whatever I would get, and how that would impact the bend in the stock. But an X made with stiff wood (or whatever I have on hand), or maybe sleeving more than one section of pipe (or even filling it with concrete?) all are options. I'll have to get a full sheet of the stock in my hands to see what it's going to take.

[M C Toyer]

WOW !

[Jack Olsen]

Thanks. Gotta keep the wife happy.

[Jack Olsen]

A week later, I was able to tear apart the test pieces adhered with VHB tape and Dow 995. Both held together very well -- I had to damage the composite material in order to get them apart.

I want to test one of the 3M Scotch-Weld epoxies that remain somewhat flexible, just to know how it would work. It would be nice to have something with a cure time in between the instant bond of the tape and the slow cure of the 995.

But the tape and the Dow 995 both seem to retain some elasticity, which I think is important in an environment with so much vibration and movement.

To get these pieces apart, I had to put the samples in a vise and pull with vise-grips and pry with a screwdriver.

VHB tape and Dow 995:



Dow 995 alone:

[2bits]

I called it the "Git er done-Drop" It was built on an extended and lifted 4x3 harbor freight trailer with an all steel frame with the concept of lightweight. Paneling interior and aluminum exterior. I just needed a short term camper and this did the trick and wanted to see how the metal frame would hold up! Did me nicely and sold it in one day for $1500

[Jack Olsen]

That looks great, 2Bits -- although I do see SOME wood in there.

Back in my slow-as-molasses world, I tested some more adhesive samples, this time with a full week of curing time.

Sika is a German polyurethane-based adhesive and sealant sold at Home Depot. Both products do not have Gorilla Glues 4X expansion property (which has positives and negatives to it).

In my testing, the sealant did a better job than the adhesive when it came to adhering a piece of Aluminum Composite Panel to 1" XPS foam and then to a 1/4"-thick piece of corrugated polypropylene. Both would work fine for this application, but were not the absolute best in this test.

Gorilla Construction Adhesive, which I think is polyurethane based, did slightly better than the Sika, at least in this test. In my destructive separation of the foam insulation from the Aluminum Composite panel, the foam broke up into pieces before the two pieces would separate.

But the traditional Gorilla Glue did even better than the construction adhesive. I'm still on the fence with Gorilla Glue, since cleaning up the expanded glue and dealing with possible bowing/distortion from that expansion might be an issue in adhering large wall sections. It works REALLY well, though. Very hard to get it apart without just chiseling away the foam:



Dow Corning 995, which is a structural adhesive used in glazing applications, has the advantage of staying flexible for a long time. I think for locations where continued flexibility is important, a mix of VHB tape and this stuff will be useful. But as a full-sheet adhesive, it wasn't quite as good as (either of) the Gorilla products.

The big surprise to me was Glidden Gripper, which is just a high-end paint primer that happens to be a fantastic adhesive for XPS and EPS foam. It was the hardest to separate from the Aluminum Composite Panel, hands down. I had to get a screwdriver in there and basically just tear up the foam to get the pieces apart. My questions with it are whether its limited ability to fill gaps (which Gorilla Glue is so good at) will be a limitation. Certainly for wall applications where I can use weight to clamp the two pieces together for a long cure time seem to suggest that it would make an awesome (and VERY cost-effective) adhesive for this project. My other question is whether there will be long term 'aging' issues for a latex paint product. But this stuff was great. Right up there with Gorilla glue and MUCH easier to work with (and MUCH less expensive, too).

I did the Glidden Gripper test after the others (I was priming an unrelated project with the kids), and didn't clamp it as well. But you can see the section where the foam came apart rather than losing adhesion, and another section that involved some gap-filling which was also very difficult to pull apart:

[Jack Olsen]

And since there's nothing duller than adhesive samples. Here are some pictures from earlier this week.

I rented a teardrop locally for a second time and did one night up in the mountains with each of my two kids. It's been a great way for me to confirm that they would like being able to camp like this more often, and also to give some thought to what I would want to build into my own camper. We were up north of Los Angeles in the Angeles Crest Forest, near the 7,000-foot summit called Cloud Burst. I brought a rope so we could make a simple swing on one of the bigger trees. And I also got a new shade canopy to sit under. Both kids had a great time. (And so did I.) The next challenge (before building my own teardrop) is to get my not-a-camper wife to come along.

This is the campsite. We've already learned that mid-week camping is a great way to get the whole place (just about) to yourself.



My seven-year-old, Max, considers himself a pro at teardropping now.



He's also pretty brave on a rope swing:



Molly is only 3, and hadn't ever been camping. But she took to it like a champ.



She gathered all the kindling for the fire, and explained to her doll how the little sticks helped to light the bigger ones.



We got great gas mileage with the car. Had no issues with traffic at all (mid-week is a great way to go). And both kids are excited about going out again.

So pretty soon I'm going to have to start building...

[M C Toyer]

Looks like a great outing and the kids enjoying every moment.

That's probably the thing I miss most about California. In the 60s we lived on the beach in Ventura County and could swim in the morning then drive to the mountains in the afternoon, then from there to the desert if we had an extra day.

Good idea on the rental to work out the priorities. We rented a pop-up when our daughter was a bit older than yours for a trip to Graceland and that firmly convinced me I never wanted another pop-up. Of course that was a very basic model where you stuffed all the extra equipment and supplies inside for the trip then had to unload and arrange everything when you arrived.

Oddly, our daughter has one now but has help in setting it up and the appliances are built in. Back then she and her mom mostly played while the old man sweated. Daughter has been outdoorsy ever since so I guess they are never too young to start.