Exterior al skin thickness with out using plywood?

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Exterior al skin thickness with out using plywood?

Postby browningbuck » Sun Feb 23, 2014 10:25 am

Hello guys, I'm working on exterior skinning and wanted to ask if anyone has used a thicker aluminum or has used any different detail that didn't include plywood? I understand that going all al is going to be a bit more expensive however there a few advantages for me doing this over using ply. This would be a light off road tear and the front section would have a thicker plate than the rest of the exterior. Total exterior sqft = 172

So here is some info I've been working on :
Typical wood with al skin assembly = .155" and .81#sqft
Some al thickness that are available = .05 , .7# (way too thin on its own), .08 , 1.13# (pretty thin still). Also .09 , 1.27# slightly interested in this maybe it'd be strong enough to avoid oil canning and denting if it's bumped? .1 , 1.41# pretty thick weight is getting up there but more importantly price is getting up there. Finally the almighty .125" at 1.76#sgft might as well coat it in gold while I was at it.

Anyway thought I'd ask to see what you guys thought and see if it'd been done?
Brian
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Re: Exterior al skin thickness with out using plywood?

Postby GuitarPhotog » Sun Feb 23, 2014 12:07 pm

My teardrop was built in 1948 of 1" steel angle iron framing and 0.050 aircraft aluminum riveted directly to it. There was no interior skin or anything under the aluminum.

The angle iron frame is welded together and sits on top of the 3/4" plywood floor.

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Re: Exterior al skin thickness with out using plywood?

Postby browningbuck » Sun Feb 23, 2014 12:23 pm

Thanks photog for the reply, what is the on center dimension of the framing on that beast? I just played with a sheet of .063 at lowes and I think I was greatly over thinking this. I am now thinking the .07 or .08 will really do well for the skin welded to the aluminum skeleton of the trailer.
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Re: Exterior al skin thickness with out using plywood?

Postby halfdome, Danny » Sun Feb 23, 2014 3:39 pm


Here’s one we saw a few years ago.
It’s was about 1/8” +/- thick aluminum.
Image
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If I remember correctly it was made in the 1940's and had a vintage military look to the inside and galley.
Don't have any more information as the guy came and left within an hour.

The "Five Wide Guys" have built a few that are all aluminum.
:D Danny
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Re: Exterior al skin thickness with out using plywood?

Postby corncountry » Sun Feb 23, 2014 7:58 pm

Welcome Brian
My tear is built with steel 1" sq. tubing. I used .040 aluminun, with no plywood backing, fastened to the steel framing with 3M VHB tape.
The aluminum is backed up with 1" insulation board.
Image
I didn"t have a photo with the insulation installed.
Maybe .050 aluminum would be better for an off road tear.
We have put over 6000 miles on the tear and no dents or oil canning.

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Re: Exterior al skin thickness with out using plywood?

Postby michaelrsydney » Sun Feb 23, 2014 8:16 pm

As an alternative have you considered an aluminium composite (sandwich) panel? The material is two skins of aluminium separated by synthetic material. It offers better insulation than solid metal and is very easy to work as it bends easily and progressively plus can be folded if grooved on the inner face.

There is a fair bit of info on this TNTTT thread:

viewtopic.php?f=65&t=58220
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Re: Exterior al skin thickness with out using plywood?

Postby GuitarPhotog » Sun Feb 23, 2014 8:41 pm

browningbuck wrote:Thanks photog for the reply, what is the on center dimension of the framing on that beast? I just played with a sheet of .063 at lowes and I think I was greatly over thinking this. I am now thinking the .07 or .08 will really do well for the skin welded to the aluminum skeleton of the trailer.


The basic upright wall studs and ceiling joists are about 13" apart. Farther apart where the door is (30" wide) and closer at the nose.

I would rivet rather than weld if I were building alum on steel. There are galvanic corrosion issues to consider and I think welding would make them worse.

If I were building a teardrop, I'd consider an aluminum frame, welded where possible and riveted where necessary. Then I'd use rivets set with a pneumatic rivet gun to hold the skin on.

There's someone on the forum who built his teardrop this way, I saw it at a DAM Gathering a couple of years ago.

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Re: Exterior al skin thickness with out using plywood?

Postby browningbuck » Mon Feb 24, 2014 10:39 am

jim thank you, great info and great looking tear
michael, ive worked with alcuabond on exterior building application and it is great stuff however im trying to weld the alum sheathing to the alum framing of the trailer so the insulation gets in the way of that unfortunately.
Photog, i wont have to worry about the electrolysis due to all of it is Al. and thanks for confirmation on stud dimensions

Everybody thank you so much you all have been a great help and hearing all the other out there that have been on the road for a while makes me feel better about this design. After searching the site there wasnt much info so it seemed as if i was getting into uncharted waters which would have been a bad idea.
ill keep every one updated. i need to get pics up but more interested in building than photos at the moment :beer:
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