Teardrops n Tiny Travel Trailers

Hi All,

I have been trying to anneal my aluminium to go round the edge of the teardrop and have been really struggling . It is kinking on the bend, getting marked because of the hammer and scratching the paint off the teardrop. Can anyone advise me what im doing wrong?...does it need to be hotter? Do i need to use a rubber hammer? is the radius of the bend too tight for aluminium to bend round?

I would really appreciate any help/advise as this is starting to get at me .

Please see the pictures below showing my problems:

Usually the trim has uneven legs and the longer one is the one that follows the curve on the flat. The short one is on the side and able to bend to conform to the shape without puckering much easier. You're trying to bend too much material and it has no where to go but up in my opinion. Check Lil Bears site for the different type profiles of trim. It may be available locally to you, or you can get it from Grant. Doug

Sheet metal workers use things called shrinkers and stretchers to bend angles. I got a pair from Harbor Freight and bent this piece of 1X1X1/16 angle.



It roughs up the finish but you can sand and polish it up again.

As far as anealing goes I've done it with a propane torch. I've heard about sooting up the aluminum and heating till the soot disappears, and other techniques but what worked for me was to go in the garage at night, turn off the lights and use the propane torch to heat the aluminum till you could see it start to glow. Put the torch facing the inside of the angle and look at the outside. When you can see the glow, you know it's time to move on. In the dark, with the lights out it is easy to see and you just heat till it glows and work your way down the lenght of the piece you are annealing.

I once fit a piece of trim to my boat and did so using many c-clamps and blocks of wood to keep the flange from puckering (got 4 really nice c-clamps this weekend for 10 bucks at a garage sale, I digress). I think that I would make a template for the curve you want to bend out of scrap wood and do your bending on it rather than the teardrop itself. In addition, you could keep blocks of scrap wood clamped to the flange to reduce kinking while you bend it. You could do the curve in sections and not have to make a full sized pattern but use one piece of wood, recutting it a bit each time to match the section you're bending.

Hope this helps.

Cheers,

Gus

It looks like at least one of the pieces you are bending is the U-channel for plywood edge applications. I'm not sure if you can get a "shrinker" jaw to fit in the channel.

That leaves you with cutting the legs down. I agree with Doug (and from experience) that you will have a hard (impossible?) time getting the long leg to bend without that dreaded rippling. A shorter leg, or softer, bendable angle may be your only hope.

I found that pencil marks on the aluminum disappear at about the right temp, but an old aircraft mechanic said it was a no-no because the carbon will eventually cause the aluminum to stress crack (haven't seen that myself, and is probably true, but probably not a worry in our application). When I did my annealing, I bought a 650 degree temp stick from a welding supply store. You heat the metal and draw on the heated metal with the stick. When it melts, you are at the proper temperature. Using soot accomplishes the same goal--an indicator that your metal is hot enough, but not too hot. The advantage of a temp stick over soot is the accuracy. Too little or too much soot to burn off may either underheat or overheat the metal, but lots and lots of folk have done it that way with success. Just don't over heat--practice on a spare piece and you will find the difference between hot enough and destroyed is ust a couple of seconds with a torch.

The couple of pieces of angle on my trailer that had to have long legs took multiple bouts of annealing, bending and straightening with a hammer. The pieces are not ripple free, but you can eventually get them pretty close.

Hi All,

I really appreciate your help . So once the metal has been heated, do you have to bend it while it is hot or will it remain flexible when it has cooled down?

Cheers,

Adam

Let it cool.

I don't think he's trying to bend a channel. It looks to be an optical "delusion".

Cheers,

Gus

eamarquardt wrote:I don't think he's trying to bend a channel. It looks to be an optical "delusion".

Cheers,

Gus

Yeah it is an "L" shape - 25mm x 25mm

Cheers,

Adam

The easiest way to anneal aluminum is if you have a oxygen acetylene torch is to burn just acetylene and soot up the aluminum your annealing then turn the oxygen on and heat the aluminum until the soot disappears. If your using a propane torch sooth the aluminum up with a candle and then heat with the torch. Then let it cool then you can go back to working it.

Scott

LET IT COOL!!!

AL is a completely different animal than Steel. It tends to get "hot short" and break up when you try to bend it while it is hot.

Perhaps you need to look at the type of aluminum material that you are bending. There are different grades of aluminum that are softer, and are better suited for annealing for curved trim.

What Doug H. said, check with Grant at Lil' Bear:
http://www.lilbear.teardrops.net/parts.html

This is link is in my notes, and have never purchased from them:
http://www.yellowdogextrusion.com/extmold01.htm

Have you thought about using the "insert molding" from an RV supply place. It bends easily by hand, or you can do as I did and make a bending jig that lets you bend the molding easily with no kinks. It was really a simple & quick job. Plus, it can be painted as well if you want. Just a thought.

Mike

I used a deadblow hammer. It just takes a lot of pounding after you soften the metal. Not perfect but not an eye sore.

G'day ADZ_4,

Get a bar of common soap and soak it until it is slimy. Spread a film of soap over the section to be bent. Heat over a propane camp stove or use a propane torch until the soap film goes black. Allow to cool and you now have softened aluminum. The black will wash and polish off.

Travel trailer suppliers should be able to supply various soft specialised corner trims so you really only need to anneal small sections for doors and drip gutters.

Over here in Oz we call Travel trailers, Caravans and Aluminum is Aluminium but the above approach worked for me.

Regards, Mark.

PS: I've put some photos in my album showing what I did.

I used the door as a template for the frame trim and screwed it every 2" as I bent it. I also clamped on backing ply to stop the trim from twisting. The 3/4x3/4 "T" tim was the least problem. A hammer with a block of wood can be used to tap out wrinkles.

1" is a bit much to bend tightly in compression. Try to use 1/2" or less if possible.

Hope this helps.

Regards Mark.