$500 Aluminum Frame: Is it worth it?

[FATSO64]

In the process of planing a teardrop build, one that would be towed behind a scion xb with a 2.4L engine. Wanting to start with a 5x8 platform, that will be light, but still ridged for what I'm looking to build. Wanting the weight to be between 1000-1300. Also looking to be somewhat minimalistic on accessorizing.
I really like the concept behind the MEGADROP, here in the forum, with the lifting top to add more space. Not looking to be as large as that one, but the concept is what I like. I have no aluminum welder, and will have to outsource that part of the labor, but all the other fab work (i.e. cutting, etc.) I can do.
That being said, with the cost of the aluminum, welding labor and headache of trying to register a homemade trailer in California, would $500 be a reasonable price for an aluminum trailer frame with aluminum decking already welded in? Its 5x8, with 3-4" tubing that has a wall thickness of approx. 3/16". The trailer is a new utility type trailer with ramp, rails, and axle, but I don't need rails or a ramp and the axle is leaf sprung and cheap looking. I plan on purchasing a Dexter Torsion axle with possibly brakes. The trailer company will strip it down to just the frame, decking and tongue for $500, allowing for a solid start to my build.
The company selling it will include the Manufacturers Certificate so I can register it with no hassle. It looks well built, with 3/16" (or so) tubing and extruded aluminum flooring (that will save the need to seal heavily underneath the flooring). Does it sound like its worth it? Just need some friendly opinions before I move forward. Also, I'm new to the forum world and having an issue uploading the picture.

[doug hodder]

I've built a 4'6" x 10 foot with a steel frame 4" drop axle 3500# on springs that came in at 960# 6 years and it's still being used regularly, (I camp with the new owners) , less food and full cooler. I also don't load up with a ton of stuff that probably won't be used. Full decking in metal isn't necessary. Licensing a tear in Ca. isn't all that big of a hassle either, not like PA....Just take in all the receipts with a copy to give them at DMV. No brakes necessary on a trailer of that weight.

Steel is less expensive and less hassle if someone else is going to design it. Aluminum isn't always the light weight answer. Watch for someone that is concerned about building something just to cover their butt. They always go heavy on the frame. The trailer in the following pic has been across the country and has been towed up to 90 mph, solid ply walls, insulated ceiling. Just my opinion, others may differ. Doug

[jss06]

Given the cost of steel, I did not spend much less than that when I built my frame. I would say it is worth it if that is what you want.

[Shadow Catcher]

I wanted an all aluminum frame (includes cabin) for two reasons, weight and no rust. Our trailer at 6X10 with a large front tongue weighs about 1600#. The down side of aluminum is finite modulus of elasticity, It may crack with age but there are a lot of old airplanes around so if done well not a problem.
The biggest effect on MPG is wind resistance but for stop and go driving weight can have an effect and for a marginal tow vehicle it can make a difference. One example. Our trip out west last summer (from Oho) meant some real altitude changes and one camping spot was a Tioga Lake at 10,000 feet and the car barely made it (high altitude = lower horse power). This is an extreme example but I think gives some idea of the problem.
It is possible to build a steel frame that is light weight and stronger than aluminum but you would be using an alloy steel that is expensive and difficult to weld, Think high quality bicycle frame 3620 chrome molly but again very expensive.
Aluminum frame, I did but there are other alternatives.

[eamarquardt]

First, here's an interesting article: http://www.thetruthaboutcars.com/2008/0 ... onspiracy/

The curb weight of the XB is 2,395 lb (1,086 kg) with a GVWR of 3,315 lb (1,504 kg). IMHO yer gonna want BRAKES.

If I were gonna do it, I'd build a frame like the one Angib has posted:



Then I'd build the cabin out using sandwiched construction (like a hollow core door) using maybe 1/4" ply spaced 1" or so apart with insulation in the side walls, floor, and roof (roof to use 1/8" ply). If yer concerned maybe 1/2' on the upper surface of the floor. Screw and glue it all together securely and it ought to be light, stiff, and good to go.

You really don't need all of the metal most trailers have in them. They have built lots of airplanes out of wood and they performed just fine. The most famous is the Spruce Goose: http://en.wikipedia.org/wiki/Hughes_H-4_Hercules Lesser known but having made a big contribution during the war is the British Mosquito: http://en.wikipedia.org/wiki/De_Havilland_Mosquito

Welding aluminum is not for the "faint at heart". If done incorrectly it will fail with little warning. A friend has a beautiful aluminum boat trailer but it is BOLTED together with not a single weld.

Hope this helps.

Cheers,

Gus

[FATSO64]

Thanks for the replies, I appreciate the answers that can be had on the forum by just asking the question. When asking a salesmen these type of questions, I just get stupid looks.
I swung by the local metal yard and got some rough prices for 2x2 square steel tubing in .060, .083 and .120 wall thicknesses. The price is right and I can tack it all together myself and then have someone who can run a clean bead finish weld it for me. I still have a bunch of R&D to work out, but as of now, my question has been answered, thanks again!