Need help bending 1/4" aluminum

[crazyal]

Have you talked with shops around you? A sheet of aluminum is pretty expensive so I assume that you'll be buying 3" strips vs a whole sheet that you'll need to cut (make sure to tell them which way you are bending so you get the grain correct). Around here most shops charge you a minimum amount of labor to cut the metal to size. Having them bend it doesn't change the price much and they should know the best alloy to use for your project. I would also expect them to cut it correctly to get the grain right. A press brake (as other have said) would work well too but if you don't have a press or a brake it'll cost you quite a bit to buy them. Northern tools sells a press brake but I think it's close to $400 (with shipping) for their smaller one that will work with a 20 ton press. You could get a Harbor Freight press for under $200. If you think you'll have enough use to justify buying them then it could be the way to go but for a couple of pieces it may make sense to just pay to have it done.

 

[bindian]

Buy 2024-T3 aluminum if you don't want to heat treat it after bending. Bending O and then heat treating will warp a huge length like you mentioned. When we had to form a part, like a bulkhead frame, we would make 2-3 parts and have them heat treated.........then use the least warped one and cut it down to size.

I would think you would need over a half inch radius for the bend. Maybe even 3/4 inch radius. But it is all trial and error with getting the right radius. Bending metal for aircraft repairs, we bend thin metal numerous times on the brake and stack it up to get the size of radius we want. Bend across the grain, and smooth the cross grain edges to a rounded edge. This will help prevent local stress cracking. I think the small (under 4 foot) brakes that are cheap will be too small to bend it. I would bend it on our 6 foot box brake at work if you were nearby. I saw a 6 foot brake auctioned off last week at Richie Brothers Auction in H town. It was pretty trashed, but repairable. A good sheetmetal shop will have a press brake and can knock numerous bends out quickly.

Bends can be hammered around wood forms held with bolts (you would need to drill tooling holes) or C clamps. Use a block of wood to hammer on, as a hammer will leave dings in the metal. A monster vise with the jaws smoothed down and radiused would work also. All our vises at work have had the steel jaws removed and replaced with aluminum jaws. The old steel jaws then are ground down and heat treated to make nice palm size bucking bars.
hugs, Brandi

 

[connor77]

Lots of good suggestions including welding instead of bending. This is a great forum with lots of people with a lot more experience than I have so I really appreciate the help.

 

[s219]

Aluminum is a pain to bend in heavier gauges/thicknesses while maintaining strength and avoiding fractures, so for 1/4" or 3/16" I would much prefer to weld myself. You can get a nice crisp 90 degree angle.

 

[LD1]

I would be really interested in just what you are making. Aluminum is a very different material than steel.

60 series aluminum dont bend well without heat. But are fairly strong.
30-series are better forming, but about 1/2 the strength
20 series and 70 series are both stronger than 60 series, but also hard to form without heat. They also cost alot more than 30 and 60 series.

I have worked with alot of 6061 and 3003 before. The 3003 is good to work with in sheet variety making bends and such. Used alot of that for guarding around moving machinery where strength wasn't really an issue. But if you get pieces of it mixed up with 6061, results wont be good, as 6061 will snap when trying to bend without heat.

And on a few occasions when strength was needed, I have used 2024 and 7075. But never bent that stuff. It was only used for making parts that had threads or something that would wear out alot faster with a softer alloy.

 

[PILOON]

I re-read and gather you want to bend across the 3" width.
What would probably work would be to clamp the strip and a piece of 2" round (Pipe?) firmly in a big vice and use body english to bend it over that clamped pipe.
If you have spare material you could even try on tighter radii.

What most folks don't know about bending is that in any bend the outer 60% stretches while the inner 40% compresses.
This makes precise bending quite a science as to accurately locate the fold point you need to add or subtract that 60 or 40% point.
That and with aluminum radius bars need to be used with more radius for stiffer and less for dead soft.
Stiffness is designated as T 1-T 6, one being soft and 6 very brittle.
Then you have different 'alloys' of aluminum with most commonly used being 2024-T3 and also called Alclad meaning 2024 alloy with a pure cladding of alu for corrosion resistance.
There exists aluminum so stiff that you can almost hone it and shave and others that resist corrosion almost like stainless.

 

[BXpanded]

The OP didn't say what he needs in the way of strength. 1100 or 3003 in 1/8" will bend 90 degrees with no problem at all, if bent across the grain. I've done that hundreds of times. 3/16 or 1/4... Don't know. Haven't used much of that but my guess is it will bend 90 with some small radius. Those alloys (actually 1100 is pure aluminum, so not an alloy) are really soft and aren't heat treatable. Most any fab shop will have a break that can bend it easily enough. If you need lots of strength, those won't do.

 

[barts]

I built a battery box for our '71 Airstream out of 1/8" plate; I used aluminum angle for the corners and riveted the corners. I'd show you a picture, but once again I cannot upload photos, sigh.

- Bart

 

[connor77]

Doesn't need to be super strong. T6, based on what I've read, will be more than strong enough. I completely understand that the thicker the material the larger the radius needs to be. I'm just having a heck of a time finding a machine to do what I'm after. I don't really want a huge press brake (have seen the harbor freight tool suggestion). I seen other types of bending machines for decorative steel that put a nice radius on flat stock but I haven't seen anything that can handle something 3" wide or slightly wider. One of the things I want to do with this piece of aluminum is to make my own roof rake that cuts the snow rather than something that actually "rakes" the snow off. Any of you that have dealt with all of the snow we've gotten and have had issues with snow on your roof probably know what I'm talking about. I think that I should be able to make something that's better than what's available commercially. The bender that I've seen that I think could do a good job is a spiral type bender - just need something to accommodate something wider than 1 1/4"

 

[bigdeano]

I've bent 6061T6 AL a few times in my hydraulic press. It's not a problem if you bend it around a proper radius. I built a simple jig with 2 parallel bars welded to a heavy base piece. I can put spacer bars in to adjust the open gap, and just lay the piece to be bent across the opening.

I bent 1/8" 90 deg using a 5/8 dia shaft to push with. A friend was building a front landing gear for his homebuilt airplane. We bent 1/2 x 3 into a U shape. I think the radius in the corners was about 1". He made a jig so it could just be pushed straight down and form both corner bends at once.

The problem with welding AL is it loses most of it's strength and will easily bend or break.