Large Radius Aluminum Bend

[RedEye]

I have no trouble with square or small radius round bends, but making a big open curve is giving me trouble. The curve isn't enough to permanently deform the aluminum so it wants to spring back. Any suggestions, practical for an apartment dweller with no workshop?

[chaksq]

I don't know what to use to make bends. I do know that you will need to bend it to a smaller angle than you want your final angle to be so that when it springs back it ends up going to the actual intended angle. I've actually taken courses in materials processing as I'm an engineering student and they covered this briefly. Judging how far to overbend it can be a bit tricky and to actually calculate it takes work and knowledge of the materials properties. Seeing as you aren't doing this in an industry situation you can probably just approximate it, just bend a little and if you need more then bend some more, its easier to bend more than to try and straighten it out. Hope that helps.

[RedEye]

The biggest radius bends shouldn't be too hard. But I'm trying to make a round housing for a 250mm fan . . . it's a bad size, the aluminum seems to be at maximum springiness. It's just about a 2 man job to bend it around the form and clamp it there. Maybe I can get a torch and anneal it without burning down the building, make it a bit easier to work with.

[Eclecticos]

How to Bend Tubing and Pipe by Hand (http://www.metalgeek.com/archives/2005/05/01/000047.php) <=-

[RedEye]

Thanks for the link. It's sheet that's giving me fits, but that'll help for building the frame. This is what I get for being determined not to build another glorified box shape.

[Eclecticos]

Sheet Aluminum? You need a brake. I not so sure about this one. .
. .looks like it might brake :D
But you get the idea.

http://img218.imageshack.us/img218/1403/15239lgiw2.jpg

[RedEye]

How would you make a 6" or 7" radius curve in a brake? I thought those were for small bends.

[Eclecticos]

I guess I misunderstood. You may want to check Here (http://www.grizzley.com/products/searchresults.aspx?q=pipe%20bender) <=-

http://img187.imageshack.us/img187/1150/h2925pf1.jpg

[danthegeek]

I think your best bet would be to bend it around a form that is a little nit smaller. Then take a torch and heat it up as best you can. You can get a propane torch at walmart that may work. Then dowse it with cold water and try to shock it into place. That should help keep it from springing back as far.

-dan

[vastonecat]

In order to bend radius in sheet metal in a well equipped shop they use a sheet roller something like this.

http://i250.photobucket.com/albums/gg259/vastonecat/PR-413_lr.jpg

you may be able to approximate the outcome with a couple of broom handles, barbells, or steel pipes. if you have anything like that lying around... maybe at work? seeing as how it is for a computer piece it shouldn't be all that large and you may be able to get 3 rolling pins and mod a machine out of them to bend your metal. The bottom 2 rollers stay in a set position but the top one adjusts up and down to get the radius, and you just run it through a few times look at the effect and make adjustments a little at a time.
Hope this helped a little.

[RedEye]

Thanks, I think annealing with a torch is going to be my best bet. As is, it takes a huge amount of force to keep it bent in the shape I want.

[vastonecat]

Well if holding it in place is an issue then get some tie down straps or maybe a strap clamp similiar to this one that has removeable corners for odd or rounded shapes.

http://i250.photobucket.com/albums/gg259/vastonecat/51VMDDHT20L_SS500_.jpg

Again hope it helps.

[xmastree]

You said it's for a fan duct? So it's not going to be that big then.
If you have any spare pieces, I would try (daft as it sounds) using a rolling pin. Place the sheet on a soft surface, carpet would probably be ok, and roll it back and forth a few times. It should start to bend the way you want it. If it doesn't, lean harder on it.

Workshop tools? Who needs 'em?

[vastonecat]

Well if it's only a short piece of tube you need then try this site and maybe you can find something to work with as they sell 10" metal duct pieces. The address is for a T fitting that you may be able to cut down to size.

http://www.hydroasis.com/hy/productdetail.aspx?id=1475&product=10-inch-metal-duct-tee/gbase/?utm_source=googlebase&utm_medium=cpc&utm_term=10%20inch%20metal%20duct%20Tee&utm_campaign=gbase_master

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