Steel or alu subframe?

[Ndmker]

I about to build my camper box, which is supposed to sit on a 80-series land cruiser frame. The living space, or camper box needs to be on a rectangular subframe. Which material should I use? Aluminium is lighter and I can use larger diameter rećtangular tube. Steel is damn heavy but it is more forgiving and stress resistant.

Weight is very important for me because using the land cruiser bottom makes the vehicle already very hefty and I need to keep the vehicle mass under 3 tonnes.

Should I bite the bullet and give it a try with alu?

 

[IdaSHO]

Build it right and steel doesnt have to be heavy.

My entire "subframe" for my camper weighs less than 150#

For the given strength and rigidity, you would be hard pressed to home-build something similar in aluminum.

1.5 .065" square tubing. 105 linear feet of it.

 

[Ndmker]

Thanks for the reply. I am aware that a box structure made of steel can be rigid and light, but I need a flat shape, a rectangle with a few reinforcements across it, a piece of plywood on top and this will be the floor of the camper. I have no space for any vertical pieces which I could 'triangulate' to give rigidity. The laws of physics tell me that diameter gives you more rigidity than the material used or the wall thickness. Below is a diagram which shows the shapes and materials I need to compare. So I assume that a 3x1" rectangular alu tube will be stiffer (and much lighter) than a 2x1" steel tube. The inner reinforcements need to be made probably of 1x1 square tube and 1/2" plywood will be attached on top of it. Of course there will also be gussets wherever possible (not pictured).




What do you guys think? Is alu worth the effort? I need to remember that weight is cruicial, because I have 1300lbs for the entire camper box, with furniture, appliances, water tanks (filled) and luggage. This is not much :-(