How to stiffen 1/2" aluminum tube?
 

I made some aluminum arms to hang my ATI fixture. I used aluminum and brushed it to match the fixture. They look really good. However, my (cheap) tube bender only goes up to 5/8", but I couldn't find 5/8" aluminum tube, so I bought 1/2". As expected it's fairly flimsy/bendy. Any ideas how to stiffen it up? I could fill the tube with something - not sure what.

Use that insulation in can. Used to fill cracks and seals. You can get it at any hardware store. It hardens pretty good and canbe cut easy. At least it's not heavy but it'll keep the shape

tube
 

2 part resin

I actually did buy a can for this purpose, but wasn't sure if it would help much.
Any particular one in mind? I know there are a lot of different kinds.

any liquid epoxy resin would do the trick,mix it poor it in the tub and leave it to dry and will be very solid.also to make sure the tub will fill up use a little bit less hardner,about 10% so it will take a bit longer to set so it will flow

You'll probably need a knee brace or something to add the strength your looking for. Filling the tube with foam or composites wont do anything.

fill it with concrete or epoxy

if the distance is short it does work,but for anything longer then 24" i don't think would work as the bar will bend

Ok well, the bar is 5' long with a 90* bend at 16". The long end is inserted into a slightly bigger steel sleeve. The distance from the bend to the steel sleeve is 13". The steel sleeve runs to the top edge of the tank.

http://images.tapatalk-cdn.com/15/09...f3bacd12f3.jpg

Epoxy has a modulus of 3 GPa or less, while aluminium is around 70. Doesn't matter how long the tubes are, it won't do jack.