In search of the "perfect" camper frame

[LukeH]

OK so I guess I’d better say something.
Sorry, I did come on a bit strong.
Yet again I apologise, what your thread title could have read was “For a wood framed camper, how’s this? Tips and tricks welcome” because I interpreted “perfect camper frame” as a request for pointers to the most appropriate materials and build method for an offroad bed loaded camper.
Yes I do have a few chips on my shoulder, they’re wood chips from the various repairs on my wood framed campers I’ve had to do (lol)
Part of my work is to create integration procedures (assembly instructions if you like) for things considerably more complicated than a camper; things that convert water flow into electrical power, or things that have to hang 38000km above us, remain pointed in the right direction to a precision of 2 µradians and not break down for at least ten years.
My career is based on analysing designs, performing failure mode and recovery (repair) analyses at a level of detail that drives me and my collaborators to distraction. And then redesigning as a function of the results.
I like to fool myself that I am capable of objectivity, sometimes.
If you manage to read between the unjustified insults and the obscene language that I appear to have used to offend you so much, there is a pretty detailed build-up analysis for a wood structured aluminium skinned box. It’s not based on any sort of “someone once said”, it comes from experience, both of my own repairs and my knowledge of materials and their behaviour under various circumstances.
So as I try to draw the positive side from every adverse situation, try to read through my post again without anger, and ignoring my insults and ignorant personal comments, there’s some useful stuff there.

Good luck with your build. Whatever you end up doing it’ll be something you’re proud of, and happy with. It will give you lots of experience so that your second build will be even better too. You’d also be amazed at how little structural timber you really need, most people cannot resist the temptation to overbuild.

I shall conclude by quoting some really obscene offensive language that may upset you:
“glass fibre reinforced plastic is easy to work with”
sorry I couldn’t resist ;-)

 

[IdaSHO]

Thanks for taking the time to post again LukeH.

I really appreciate it.

 

[Doin_It]

Well after a 1.5 years of talk about building, I'm waiting to see where this is going or when it's starting.................

 

[IdaSHO]

Like most, Ive always got a few more irons in the fire that I should.

Unfortunately, the camper is about 5th on the list of projects. And there are a few large ones in front of it. The largest being a $15k basement remodel on our home. I havnt even had time to put more pen to paper. :snorkel:

 

[tamangel]

any updates?

Mike

 

[IdaSHO]

Nope.

Still on the back burner. At least this thread has been able to put a lot of the ideas in my head onto paper. It will really help once I finally start building.:chef:

 

[IdaSHO]

I might as well update this one, just to show that this thing is still in the works.

Right now I have a start-to-build date of Winter 2013. Seriously. I simply have to many projects in the fire, and many more that will take priority.

This one is a long-term priority though. So things will be thoroughly thought out. And time will allow me to make many needed adjustments and alterations prior to building. By the time the start date rolls around, I will be 100% ready and plan to have ALL materials on hand, ready to go.

This week I did some pretty good research on the materials needed to create the shell. Subframe (steel), framing (wood) insulation, Skins, floor, and siding.

Putting things on paper like this helps me not only keep on track of weight, but budget too.

So a complete shell, finished inside and out is looking to weight just 1012 lbs.

I think Im on the right track :wings:

And it looks like I will miss my R14 hopes. The highest R-value foam we stock at my work is the Tuff-R (foil faced). But I have found it has horrible flame resistant qualities, and it is bloody expensive. So the Blue closed cell foam will be used. R10 for the foam, plus whatever minute R-value I might obtain from two layers of 1/8 luan ply and one layer of siding.

Also, after striking out completely with a decent readily available (around here) aluminum siding, I have decided to go with a commercial FRP product by Crane Composites.



I also tossed together a simple cross section to help work out the construction details.

From left to right for the wall section:

Aluminum molding, FRP, luan ply, 3/4"x2" pine framing over 2"x2" .09 steel square tubing, 2" rigid closed cell foam, Luan ply

From bottom to top for floor:

1/2" treated ply, 1" rigid closed cell foam, 1/2 ACX ply underlayment.

 

[rdraider]

I used the Loctite PL polyurethane series adhesive caulking compounds on my camper. I also used Titebond III on the frame joints as the wood will give way before that stuff will. I built a 1x3 wood frame then sandwiched it between 2 sheets of 1/4" ply using the PL stuff, with blue board foam sheeting insulation glued to everything with PL stuff. Seems prettty stout to me.

 

[MultiSmog]

QUALITY = Fit for the purporse

I have been thinking for a long time how to build a camper and therefore, despite whatever other people have chosen as their personal preferences, I have big respect for the people that actually got out a built something, regardless of the materials.

Anyway, my forté is the analysis and strategy part, not on the operations part so here is what I can contribute. No pictures here.

1. Definition of the mission.
A camper that will withstand the rigors of _________ travel. Define your travel expectations.
Although it is nowhere mentioned here that this is about traveling off-road I am going to assume that is part of the objective otherwise all of us would be just shopping for an off the shelf camper or trailer.

Expected Use Conditions:
I am going to assume this means lots of washboard dirt roads, uneven terrain, steep inclines, twisting frames, branch/rock damage, lots of dust, moisture and condensation, and likely to carry a lot of stuff (water, fuel, toys, supplies) which means weight.

2. Analysis of different industries and their materials.
a) Standard vehicles.
They use steel mainly, plastics for weight saving, some composite panels, some higher price vehicles use aluminum to save weight. Vibration is close to non-existent although some suden movement is constant. Vibration is from drive-train mainly, not road related.

Looking at vehicles that are subject to the Expected Use Conditions (pickup trucks used in farms) they are in a miserable shape in a short time: dust everywhere inside, noise from rattling parts that are coming loose, doors that do not align anymore, bent parts everywhere specially when cargo is hauled, rust appears on the undersides.
I have to mention that the above mentioned damage is ALMOST ALL OF IT due to the vehicle moving and not the environment. I base this comment on vehicles that I saw in Alaska abandoned in the forest that were almost pristine as in rust and cosmetic matters. Use is what creates the difficult conditions to these materials: movement, vibration, mud, splashed water, stress.

b) Airplanes
Mostly made of aluminum, smaller types use canvas and wood, large ones use composites, mainly for weight savings. Lots of vibration from propeller and engine but not that much shaking from turbulence, at least compared to cars and boats.
Some cracks develop over time at some critical point but they are minimal but you cannot understate the amount of engineering involved on airplanes due to the obvious safety reasons. Most aluminum used is not just aluminum but special alloys.

c) Boats
Extensive use of Fiberglass and sandwich fiberglass mainly, some aluminum boats where hitting obstacles is not only expected but a certainty part of boat use: river jet boats. According to direct questions on why use aluminum for such application the answer was damage resilence and weight aspects are the top priority BUT noise, heat insulation and visual appeal are way way down. Don't beleive me? Go and ride a river boat for hours and then you tell me.

Boats of every type will encounter more abuse than any other vehicle: Constant vibration from higher engine rpms and sudden strong forces (hitting waves/choppy waters), constant contact with water. Heavy loads is not a big consideration besides on high stress point on transom and engine mounts and seats/decks (at least in that's the case in recreational boats).

On the boats that had wood (even when completely encased in FG) that I had a close contact with, all of them failed to rot/water intrusion/dryness cracks/stripped fasteners.

Based on the above, my conclusion is, that due to easy of use, budget restrictions, strength, weight, durability, etc you are better off using a combination of materials. From metal frame in some parts for strength/durability/cost; composite in others for weight, durability and cosmetic reasons; Wood in others for ease of use, cost and availability. What to use were? It is mostly dictated by common sense in the most obvious parts, by personal preference and knowledge of most others and finally by our own self imposed restrictions.

In every case a camper that exists will always be a better shelter and better ACTUAL quality than just rethoric and fantastic dreams.

Saludos

 

[RoosterBooster]

hmmmm .... did you consider any kind of vapor barrier ?

looking at your cross-section i would fear that you get condensation on the steel (due to thermal bridging as the underside of the steel is exposed to the outside) and on the inside of the FRP skin.

 

[IdaSHO]

Good thought. Ive thought about that too. Since the luan ply will be bonded to the wood framing inside and out for strength, I see no way to apply a vapor barrier. Any suggestions?



Current plans include filling the cavity of the 2x2 steel tubing with rigid foam, and coating the entire subframe in a liquid bedliner material.

Im hoping that will be sufficient to eliminate any substantial sweating.

BTW, the bottom of the subframe will not be exposed directly to the outside. That section will sit on the steel flatbed frame of the truck.

 

[RoosterBooster]

closed cell rigid foam is actually a vapor barrier, but the wood studs and any other opening are maybe a potential vapor leak.
your right; i forgot that you are bonding... so tape between the rigid foam pieces (over the studs) is not going to work .

if you plan to paint the inside maybe you could use a bathroom/kitchen paint that is formulated as a vapor barrier ?!? .

 

[IdaSHO]

The vapor barrier problem has been resolved. Im going with an exterior wall coating. No metal, no seams.

Still looking at my available options for coatings, but have narrowed it down to a polyurea blend, or a very robust acrylic elastomeric.

I have been keeping at it with google sketchup though. The layout is coming together.
Note the rear slant. This should aid in aerodynamics a bit, as well as help shed moisture and reduce snow-pack. It will also let me install a nice roof vent, without increasing the overall camper height.

The parts collection has officially started as well.

Ive got 5 dual pane Huhr windows in the mail.

Stay tuned :ylsmoke:

 

[IdaSHO]

Massaging the layout a bit...

Its getting real close. Every time the wife comes into the office when Im working on this I can feel her hovering behind me.

"what do you think?"

:silence:

"okay, what would you CHANGE?"

And she contributes. Which is exactly what I want at this stage of things. Now beyond structural and mechanical, layout is everything.
And who better to dictate the layout of the kitchen and cupboards than my lady! :sombrero:

One of her suggestions was to actually make the door a bit narrower. From a 30" door to a 26" door. This moved the fridge and the pooper back, allowing for more closet space between the cab-over and the fridge.

 

[bajadulce]

followed this thread for a long time and some really good ideas in here.

FRP is a great and inexpensive resource. I used it extensively on a camper (the roof + front overhead cab). Smooth side "out". To add a little more rigidity to the material, I added 2 layers of fiberglass cloth to the textured "underside" of panel (roughed it up w/ grinder of course) and this proved to be a big help. So you might experiment with a small swatch and judge any gained benefits yourself. While aluminum siding is of course lighter and cheaper, with the FRP, you will be able to glass the joints and thus make for a perfect 100% waterproof joints. So that's pretty nice! The frp should be painted of course to avoid UV damage.

Computer rendering looks great and lots of room in that overhead bunk. What are the plans for the roof in terms of structure and will it be entirely "flat"? Some sort of convex bow would be nice if you can pull it off. Even a little would help. I like your sloped rear roof above dining area where headroom isn't an issue. Should help with rolling wind resistance?

Can't say I ever felt the need for a camper to have a sink or a bathroom, but I'm sure that when they are used, they are great.

Interior layout looks great and well thought out. I agree 30" door seems a bit overkill. Myself, I really enjoy a lot of counter space in a small rig more than anything + as open and free as possible. Maybe that one cabinet that extends all the way to the ceiling on the left side could be cut down to the counter height. This would allow a slightly longer counter and not block out the rear dinette as much. Extra counter top that extended to the dining area would be great for placing things while eating.. things like extra pots or dishes, beer, dip, salad dressing bottles, etc, etc. Always seems a need for easy access counter space in a small kitchen/dining area. Or even a place to quickly clear table of dirty dishes for that matter haha. In any regard, you might find the cabinet cut down to counter height might serve better than a closet.

Looks like you're having a lot of fun!
Steve H.