Contemplating building my own camper

[IHDiesel73L]

If you're doing luan plywood over a foam core and bond them well I think you'll be surprised at how sparse you can be with actually framing members. The cabover is entirely geometry driven, length and sidewall height being the main ones. Again though with the solid wall panel you'll have a lot going for you, in the side walls it'll act like the web of an I beam so then on the top/bottom of that section you just need the right amount of your chosen framing material to handle the tension (on the top) and compression (on the bottom). Since you're talking about steel it realistically won't take much. Again this assumes you solidly bond your wall panels and use them structurally (they need to tie into your framing solidly, not just be affixed to it).

So in order for the panels to provide strength to the frame you need to do more than simply bolt them on. Let's say you were doing an angle iron frame with the flats facing out toward the panels. Would it be wise to bolt AND glue the panels to the frame then apply epoxy at all seams (inside and out)? I would think that would be the only way to make the outer panels function as a one piece shell. Am I at least getting warm?

 

[pods8]

So in order for the panels to provide strength to the frame you need to do more than simply bolt them on. Let's say you were doing an angle iron frame with the flats facing out toward the panels. Would it be wise to bolt AND glue the panels to the frame then apply epoxy at all seams (inside and out)? I would think that would be the only way to make the outer panels function as a one piece shell. Am I at least getting warm?

I said they need to be structurally tied together. This could be done with enough fasteners but is usually more suited to the larger surface area of adhesive bonding. Doing an angle iron frame and gluing the panels to it like you're saying could work IF you use the right adhesive. This is an issue though that I'll not be able to provide enough insight on and that is selecting the right adhesive to deal with the differing materials in regards to thermal expansion. Epoxy probably doesn't have enough give in it to allow things to thermally cycle without eventually failing. I could be wrong on it but do your own homework on it. I believe folks building rigs have used adhesive tape products of a specific thickness to allow enough give but I haven't looked into them much.

 

[ki4iwd]

i agree!! wish i had taken pics before we put the sides back on would be easier to show you. i took 2x4s and notched the 4"side so that the sheet would fit flush .1 1/2 " of the 4" side was cut down 3/4 " ( the thickness of the panel )so that when the frame was built you had a panel with a 2x4 frame around it. the panels were atached with liquid nails and screws.so what we ended up with was a frame of 2x4s with the 2' x 7' panels atached in such a way that it was one solid piece all joints in the frame were notched so the whole side was a 2" thick wall.when we connected the front and rear walls we inset the frame members so they basically became one piece also. i will try to get a drawing posted or may build a small panel to show how it was done

 

[IHDiesel73L]

i agree!! wish i had taken pics before we put the sides back on would be easier to show you. i took 2x4s and notched the 4"side so that the sheet would fit flush .1 1/2 " of the 4" side was cut down 3/4 " ( the thickness of the panel )so that when the frame was built you had a panel with a 2x4 frame around it. the panels were atached with liquid nails and screws.so what we ended up with was a frame of 2x4s with the 2' x 7' panels atached in such a way that it was one solid piece all joints in the frame were notched so the whole side was a 2" thick wall.when we connected the front and rear walls we inset the frame members so they basically became one piece also. i will try to get a drawing posted or may build a small panel to show how it was done

That would be great-I kind of get the visual, but seeing it would help. I just happened to be at Lowes this morning and took a stroll through the building materials isle. They sell a green foam that comes in 1" thick 4x8 sheets for $11.75-now, you could go the same route and use liquid nails to attach luan plywood, or I was thinking you could use hardboard or masonite-$6.75 a sheet! Of course it says not for applications where moisture could be an issue, but I would imagine that with a thick coat of epoxy all around it would be ok? I'm not sure what the epoxy costs along with how much liquid nails goes into each panel, but the materials to start would only cost $18.50 a panel. Just a thought.

 

[pods8]

That would be great-I kind of get the visual, but seeing it would help. I just happened to be at Lowes this morning and took a stroll through the building materials isle. They sell a green foam that comes in 1" thick 4x8 sheets for $11.75-now, you could go the same route and use liquid nails to attach luan plywood, or I was thinking you could use hardboard or masonite-$6.75 a sheet! Of course it says not for applications where moisture could be an issue, but I would imagine that with a thick coat of epoxy all around it would be ok? I'm not sure what the epoxy costs along with how much liquid nails goes into each panel, but the materials to start would only cost $18.50 a panel. Just a thought.

I've found foam selection varies quite a bit based on geographic region. That said I'm not familiar with any green foam, did you happen to catch the manufacturer and/or trade name?

I'd shy away from hardboard, its just pressed sawdust, not really any structural properties. Spend a couple more bucks to at least get a true plywood.

The epoxy I'm using runs ~$40/gal when bought buying over 10gal, ~$45/gal when around 2.5gal, ~$50/gal when buying around a gallon. I'm not sure what your coverage rate would be off hand but I'd assume you'd be using similar quantities as you would with liquid nails (potentially more liquid nails if it doesn't squeeze flat well).

I would say buy some materials and make a test piece and see how robust it is with the liquid nails, I have no idea how well it bonds to foam. In general though most construction adhesives stay flexible to a bit, you decide if that is a positive or negative in your build.

 

[IHDiesel73L]

I've found foam selection varies quite a bit based on geographic region. That said I'm not familiar with any green foam, did you happen to catch the manufacturer and/or trade name?

It's branded as Lowes' own. It's a seafoam type green with a shiplap joint at the edges. I looked for it on the web, but as you said, it likely varies by region (I'm in the Northeast) so they probably don't put it up there. I did find that Titebond does make a foam specific adhesive though-that might be worth checking out.

 

[IHDiesel73L]

Not sure if this will be a repost, but a good blog on building a foam core camper shell. This guy is using carbon fiber-pretty snazzy.

http://www.hookedupfilms.com/huf-adventure-vehicle-part-iv/

 

[pods8]

Yeah I've been chatting with him and we've been sharing ideas back and forth. Him starting his camper is what lit the fire under me to start researching working materials and designing a camper. We have some differing thoughts on a few items but there is more than one way to skin a cat at times.

 

[ki4iwd]

the foam we used was pink and 1/2" thick.i forgot that i will be gone this weekend so it maybe mon or tues before i can get it posted but i maybe able to get a drawing up tomorrow

 

[IHDiesel73L]

Yeah I've been chatting with him and we've been sharing ideas back and forth. Him starting his camper is what lit the fire under me to start researching working materials and designing a camper. We have some differing thoughts on a few items but there is more than one way to skin a cat at times.

The thing that surprised me most was the lack of framework-I wish he had some photos of the aluminum crossmembers by themselves though. In any event there doesn't seem to be much there, but it looks as though the 2" foam encased in carbon fiber will be pretty stout.

 

[pods8]

The thing that surprised me most was the lack of framework-I wish he had some photos of the aluminum crossmembers by themselves though. In any event there doesn't seem to be much there, but it looks as though the 2" foam encased in carbon fiber will be pretty stout.

I will not have any structural frame work in mine. I will have wood embedded in some areas for screw attachment purposes, etc. and I also will likely have a grid of plywood strips in there that make contact between the two glass skins to help ensure things don't delaminate in the larger panels but it will not be a structural frame. The skins will be providing it all.

You need to be really careful about using aluminum in a epoxy based structural skin application, it technically should have the oxide removed first and its surface etched. Even then on bonding surfaces you might be risking delamination between the two. So you need to be cautious on how they are structurally accounted for (basically you should probably think of them as being stand alone to be able to support things).

 

[getout]

I've been thinking about doing something similar and have spent a ton of time looking at this teardrop forum: http://www.mikenchell.com/forums/

They've got tons of experience with sandwich wall builds. Worth looking at ideas for sure.

 

[IHDiesel73L]

So today was a slow day at work and I finally decided to download Google Sketchup-here's my first crack at designing a foam core panel camper:

I'm really just working off of shapes of campers that I've seen, the actual dimensions of an F-350 crew cab, and the dimensions of the flatbed I plan on using. Also, you'll note the "bumpout" just behind the cab which is for the auxiliary fuel tank. The idea is to build the two side walls and rear wall as single pieces using 1/4" luan or some other stiff sheet material as the outer skin and 2" foam board as the core. I tried to make each joint really lock together, as you can see in the overhead view and in the front view to an extent. I haven't gotten around to designing the front pieces yet, but it would be the same idea. The reason I decided to recess the front pieces into the side pieces was that I thought if I used a stiff enough outer skin I could incorporate metal crossbraces that would bolt to either side to support the cabover bed (same for the roof), etc... The foam core panels would rest on these (with wood dowel pegs at each end as well and then the entire outer and inner shell would have fiberglass applied to it. At least that's the idea. Questions, concerns, comments?

 

[tom]

IHDiesel,

I considered a foam core build using a 3 inch foam core covered with .024 aluminum on both sides. Theses panels are mass produced( lower cost) for the constuction industy and structualy rated. They come 24 and 48 inches wide up to 40 ft. in length. Thicknesses are 2, 3, 4, and 6 inches. Check out Town and Country Aluminum.
In their catalog there listed under their patio/roof material section. They also stock all the caps, channels etc. for the 3 inch. They actually make entire buildings out of the panels, connecting them together with corner channels and H channels.

More food for thought. Enjoy your build project. Will be interested to see what direction your project takes!

Tom

 

[oneeyedjackass]

Question for you pros....
I'm also contemplating a camper build. Like the idea of aluminum framing but having a hard time wrapping my brain around how to connect framing members without welding. Is there company that makes this sort of hardware? Any other ideas out there?
thanks