So which material should you use?
I’m not particularly biased towards any material so I’m hoping I can take a honest look at all materials available to see what works and is not too difficult to work with.
Wood – a lot of caravans and slide ins use wood frames, I don’t mind working with it but I’m also aware it’s not as permanent as metal. Here in Melbourne also, the weather could cause a lot of issues fast. There is also the question on strength. This camper needs to fold out every which way and seal well. There can’t be any twisting or movement.
Fiberglass – definitely worth a look at. Lots of caravans & campers are using this as the base construction material. One slide on (the Innovan) even has their entire internal structure made from a fiberglass mould. So is it easy to work with? If you had to make all the moulds and do every step yourself, I would think it would take a lot of time and effort. Once off constructions would be easier (no moulds), but the final finish of the material may be a little rough. Obviously some components of our camper will need to be fiberglass like the fold over bed (everyone else does it this way too) so some knowledge of these construction methods will have to be employed.
Steel – permanent and would be very easy to weld up a frame out of mild steel. The concern here is likely the weight factor.
Aluminium – rust proof and lightweight. One of the most popular materials to use on Slide On campers here in Australia and anything Ute based (tool boxes, canopies, etc, etc). It’s tried and tested. But can I weld aluminium? That’s a no. Can I learn? Short answer is also a no, not in the time frames I want be-able to accomplish the project.
Aluminium has really appealed to me of late because of the lightweight & strength properties – even the ease of working with a material softer than steel (easier cutting, grinding, etc, etc) but I don’t want to outsource the framework to a welder.
A quick search into building with aluminium actually showed a lot of problems in welding it, not only can welds fatigue and crack (especially on corrugations) but the only real way to test for a good weld is to x-ray them.
So what do others do? Well aluminium ute trays are very often bolted & riveted together rather than welded because it takes the vibrations better and lasts a lot longer.
So that’s where I started. Maybe I could build the entire framework with bolts or rivets? Lightweight aircraft actually use gussets and rivets in their fuselage construction, maybe that would work?
Here’s a very rough sketch of how a gusset & rivet based framework might work. There is still quite a bit of work involved in riveting the entire structure, so the search is still on as to other methods.