Camper Shell Materials

[iandraz]

I think the aluminum is a good idea, possibly better than my choice of steel. You can get custom extrusions much more easily than with steel, the corrosion resistance is nice, and with the right design the overall strength can be just as good as steel.

The biggest plus for aluminum is the higher coeffecient of thermal expansion. This defines how much the material expands/contracts with changes in temperature. To avoid problems (separation/warping) you want to have them as close as possible for the different materials. Most foams and plastics expand at a rate 5-10 times greater than steel. Aluminum expands about twice as much as steel so it is a much better "match" for foam.

http://en.wikipedia.org/wiki/Coeffic...rmal_expansion

[skysix]

The Rhinokore heavy duty oil-patch panels made in BC have promise - if you can have them made with a smooth surface (they are made with a rough surface for friction) or in a thinner model (2" R10) since a 3" panel takes a lot of volume away from a midsize or small camper. Almost the same R value as high density foam (the blue stuff used in construction that Dow makes - R5 per inch)

- interesting side note though. They can be obtained in very long lengths to be used as bridges. An 8' by 14' panel could be cut into twelve 7' long sand matts or six 14' bridging panels. They have a pic of a 3 inches thick panel supporting a John Deere 7510 Tractor (15,137 lbs) over a 14 foot free span, maximum deflection: 1.3 inches

Here is a link to the manufacturer of those panels used by many of the European builders.

http://www.ormocar.de/en/sandwichplatten/

Does anyone know what the insulation value of Nida Core is per inch of thickness? And does it need a protective layer on the outside to prevent tree damage / on the inside to attach fittings/cabinets etc to?

[mhiscox]

And does it need a protective layer on the outside to prevent tree damage / on the inside to attach fittings/cabinets etc to?

As you'd guess, attaching stuff to the inside of a NidaCore cabin isn't just a matter of screwing things onto the wall, since the only solid thing you hit is the thin outer layer. Imagine attaching cabinets to very thin drywall.

The elegant approach is to create channels in the composite into which you glue hardwood strips to screw everything to. You can also glue or VHB tape plywood to the inside where you need to mount things, the thickness of the plywood being dependent on what you are mounting.

In any event, the inability to mount things straight to the NidaCore is a big drawback of this sort of construction. Remember, too, that you won't be able to easily fish any electrical wiring through the walls, so figure all of your wiring will have to run through exposed chases or behind things you mount (or maybe, as some have done, between the finish floor and the subfloor)

[Peter_n_Margaret]

for home construction, I currently plan to build a fiberglass foam sandwich type shell. This will be around an aluminum cage, or maybe steel?.

I built this body using FRP/Urethane foam sandwich over a lightweight steel tube frame and Sikaflex. The interior fittings and furniture are also sandwich panel and become part of the structure.

The steel frame was totally superfluous.

Slideshow.

Cheers,
Peter

[Peter_n_Margaret]

Peter, the sandwich panel structure is so strong that the steel frame is not required, except for the areas where there are very high loads, like the spare wheel mount.
The complication of a seperate frame is that you must allow for the differential thermal expansion between the steel and the panel. In my case this required Sikaflex glue joints of 3.5mm thick for joints up to 4m in length. Aluminium would be worse.
Joints where high strength are required can be 'capped' inside and out with 1.6mm aluminium angle.
As I said above, making the inside stuff from sandwich panel too makes the structure hugely strong and still very light.
This body is made from panel that is 19mm thick (1.5 to 2 mm of FRP each side and 15mm of HD foam core). Increasing the foam thickness increases insulation significantly, without adding much weight. This material was about 5.5kg/sqM (similar to 9mm ply, but much, much stiffer) and of course it has a stunning finish by default. Not cheap though - about A$150/sqM, but the result is brilliant.
This body has now done 150,000km of serious travel over the last 5 years. There are some slideshows in the link below.

Cheers,
Peter

[Peter_n_Margaret]

Thanks for the build pictures Peter. Turned out great.
Do you drive with passengers in the back? Do you feel it is strong enough for a roll over?

Not typically, although there are 2 seatbelts there that are engineered, but not approved. The body is certainly strong enough, but the table between the seats needs to be removed for approval when passengers are in the back and the air circulation is fairly poor. There is no aircon in the back either.


Cheers,
Peter

[Bike_Mech]

I was thinking about building a frame out of it also. I'm not sure about using it for structural frame of a rig since the constant vibration of offroad driving might be too much for the mechanical connections, and I don't know about welding the unique shapes of the t'slots. But I think it would be great for interior and exterior accessories and furniture systems.

-Chris

Bike_Mech - posted this link in "Sonke's hard-side popup camper" thread

http://www.8020.net/

Would this stuff work as the frame to build a composite shell (FRP skinned foam/balsa cored panels) around? The idea is since the composite shell is the main structural element the frame is just needed to mount door/windows/cabinets to & as a form to build the panels around. This system would certainly be light & easy to build with - without welding...although perhaps you could use welding as well after it's assembled...Looks like an interesting material. Peter

[Sleeping Dog]

I was thinking about building a frame out of it also. I'm not sure about using it for structural frame of a rig since the constant vibration of offroad driving might be too much for the mechanical connections, and I don't know about welding the unique shapes of the t'slots. But I think it would be great for interior and exterior accessories and furniture systems.

-Chris

As an alternative to welding, one possibility would be adhesives.

Jim

[Peter_n_Margaret]

As an alternative to welding, one possibility would be adhesives.

Jim

Our rig is totally built with Sikaflex 252. There are no mechanical fixings (except for cupboard hinges etc).

Cheers,
Peter

[HMR]

Checkout this site: Truckconversion.net. Some interesting ideas for DIY campers.