Using 0.040 skins

Wow, This is going to be a big topic.

Yes, I have done a couple of trailers with the Semi Trailer roof skin. I buy mine locally at a Utility Trailer repair shop about 50 miles from my home. It's 103" wide by .040" thick. It's on a roll and is sold by the linear foot. The last time I purchased it the price was $15/FT, which is a little cheaper than your price per square foot. The best part, is you can buy it locally, and save a bunch of money on boxing and shipping. I bring two vice grip pad clamps to clamp the edges after it's measured, cut , and re-rolled. Tell the guy, there's a $20 tip, if he try's not to dent it, offer to help them cut and roll it. I help him carry it to my trailer. The first time I purchased it, they loaded it with a fork lift and it had dents every three feet. In general they beat the crap out of it because nobody cares on a Semi Roof, but we see the ends of the roof skin on a canned ham.

Since it's made to be used on the very top of a Semi Truck trailer, it's a crappy finished metal. It has lots of mill finish irregularities (they look like craters). It does not polish very well if that is a consideration. It would be best to epoxy prime and paint it, if the curved ends will show on your trailer.

If you had access to a buddy with a sheet metal shop, he would likely have a 12' long metal brake. I do not know how long your wall is, but 12' is a standard "long" metal brake, you will have a tough time finding something longer if you need it. Note, RV skins are bent with a table roller, not a sheet metal brake, it's very different way. Yes, with a brake, you could put the 3", or 4" brakes into the .040" without any problem. Due to the size, your going to need 3 or 4 people. Two to hold the metal, and two to operate the brake. IMO, the "S" lock on the ends would be very difficult because you need to flip the "over 20 foot" long piece of metal over without bending or kinking it. The next issue is the seam will look thick and clunky because the .040" will not bend as tightly as the .028" or 030" RV skins. If you go this route, using a lap joint might be the better choice. In my builds, I did it as one piece, the entire front, the entire roof, and the entire rear, were all one piece of metal, no seams. The down side to this route, it's virtually impossible to build a completely symmetrical trailer. The normal "S" locks allow for variations in the roof and wall skins. The larger one piece roof will almost always have puckers in the corners because the metal will not accept a compound curve.

I have actually installed roofs with .040" aluminum. It bends over the edges just fine. Use a backer board to hold it down (reduces spring back) as you are making your bends. It's a little tougher to cut. I use right and left aircraft snips on .040" metal, where I use normal tin snipe on the .030" metal. I use a HF 1/4" crown stapler and drive staples through the 040" roof (and the .030" wall )skins. The key is you have to find the sweet spot on the air pressure. Too much pressure, and you drive the staples through the metal. Too little, and you get the staples bending over and not penetrating the skins. Make sure you drive the staples at a slight angle so they do not curve back and poke through the skin if the bend. In general, I would say it's really not much different than doing a roof with .030" thick metal, it's only .010" (or three human hairs) thicker.

Going through the effort of bending the roof skin over will give you a much better installation than using the corner cap trim, IMO.

John

Joe,

I agree with John.
I have included photos of a camper I built back in 2012 that we have used a lot (over 35k miles).  I used the .040 trailer aluminum on it, actually bent all the trim from the scraps.  I have a friend that let me use his metal brake, but did it all by myself.  It is difficult to waller around by yourself, but it is possible.  But, since you've used it before, you are aware it is very soft and scratches easily.

As far as polishing, it can be done.  You will probably have to go over it every year or so, but can be done.  It doesn't polish up as nice as better aluminum, but it will shine. 

After we got back from our only camping trip this year (actually camped, not just travel) I decided to test a random orbital polisher (variable speed) I purchased several years ago.  I used White Diamond Metal Polish with the polisher.  Doesn't take much, use polisher at a slow speed, took about 3hrs to do this one side.  Did small areas at a time.

The before picture is the side I haven't touched since it was built, 8 yrs of oxidation. (sorry they're so big)


After, this was just a quick job, could probably go over it again and remove more mill marks...


Here's a better side x side comparison when I started the back


and here's pic before showing the polish I did to the front (different method) several years ago and how it's weathered


If you'd like to see more angles, here's a link to my dropbox folder: Whitney's Weakender

It can be polished by hand using this product, actually has great results, it's just a loooooot of work (read elbow grease).

As always, just my thoughts, didn't say they were good ones...

The side had never been touched other than washing.  I've stored it in my s-i-l's garage for the last 4 or 5 years when we're not using it, sat out 24/7 before that.  The trailer aluminum has a oily like film on it that needs to be cleaned off, leaves your hands nasty.
My original intentions where to paint it, but you see how that went...

SS panhead screws.

Here's my build journal on TNTT website: Whitney's Weakender