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Woody
Woody UltimaDork
3/17/12 7:05 a.m.

I need to put a 30 degree bend in a piece of 1/8" aluminum. Any pointers? Can I do this cold or do I need to heat it?

I'm trying to make this...:

Photobucket

...look like this:

MG Bryan
MG Bryan Dork
3/17/12 7:11 a.m.

Do you have a metal brake? If not, have you considered building one?

mw
mw HalfDork
3/17/12 7:24 a.m.

A metal brake should do it easily. No need to heat.

Woody
Woody UltimaDork
3/17/12 7:24 a.m.

No, but I frequently scour Craigslist in the hope of buying one.

mw
mw HalfDork
3/17/12 7:28 a.m.

You could also do it in a vice with a hammer. If your vice isn't wide enough to cover the width of that piece, clamp it between two pieces of heavy steel that are (clamp along the bend line). Then slowly start working it with the hammer. Don't try to get all your bend with one big hit.

akamcfly
akamcfly Reader
3/17/12 7:33 a.m.

Grain direction is important when bending aluminum. the bend must be across the grain.

Also T6 temper doesn't like to be bent - it's kinda brittle

redrabbit
redrabbit Reader
3/17/12 7:36 a.m.

I would do it in a vice with two pieces of steel or wood the ful length of the bend. Harbor Freight might have a brake. Was that done on a bandsaw? Looks nice.

44Dwarf
44Dwarf Dork
3/17/12 7:50 a.m.

1/8 thick you'll likely never find a brake at GRM prices to handle that. Got shop press? Buy the V block type bender attachment.

Dr. Hess
Dr. Hess UltimaDork
3/17/12 8:03 a.m.

It helps A LOT to anneal it. Get a black Sharpie marker. Scribble on the piece where you want it bent. Heat the area up with a torch until the marker lines fade. Let it cool slowly. Now it's soft. Practice on a scrap piece first, because the difference between just right and OOPS with the marker can appear rather subtle the first time you do it. I learnt dis from watchin' Jessie James make bike tanks.

Then, what I do with larger pieces is clamp a piece of angle iron in the vice, clamp the piece to the angle iron where I want the bend, then start working it a bit at a time with a mallet. For that smaller piece, you could clamp it between 2 blocks of wood at the bend in the vice.

Woody
Woody UltimaDork
3/17/12 8:36 a.m.
redrabbit wrote: I would do it in a vice with two pieces of steel or wood the ful length of the bend. Harbor Freight might have a brake. Was that done on a bandsaw? Looks nice.

Nope, Jigsaw. It's still a little rough, though I've cleaned it up a it since that photo. I got rid of my band saw years ago because it was worn out and kept throwing blades. I'll get another someday. I miss it.

patgizz
patgizz UltraDork
3/17/12 8:44 a.m.

take to harbor freight, tell them you want to see if their brake can do it before you buy, bend it, tell them see ya later.

a brake is a great investment, i highly suggest buying one. i bent up some aluminum last night to make a pcm cover.

Knurled
Knurled Dork
3/17/12 9:17 a.m.

What grade aluminum?

I forget which is what, but hearing the guys on specialstage talk about makign skid plates, some grades of aluminum bend easily, others are more likely to crack than to bend.

And then the debate continues on which is better for a skidplate - super-strong yet brittle, or bending but stays in one piece.

iceracer
iceracer SuperDork
3/17/12 9:23 a.m.
akamcfly wrote: Grain direction is important when bending aluminum. the bend must be across the grain. Also T6 temper doesn't like to be bent - it's kinda brittle

Grain ?

Woody
Woody UltimaDork
3/17/12 9:24 a.m.
Knurled wrote: What grade aluminum?

It is approximately the same grade as one would use when making a sign with the speed limit posted on it.

Photobucket

Zomby woof
Zomby woof UltraDork
3/17/12 9:30 a.m.
iceracer wrote:
akamcfly wrote: Grain direction is important when bending aluminum. the bend must be across the grain. Also T6 temper doesn't like to be bent - it's kinda brittle

Grain ?

Also, if it's cut properly, you can count the rings and tell how old the billet was.

peter
peter Reader
3/17/12 9:31 a.m.

If you get stuck, my buddy down in Danbury has a metal brake (though the brake itself may be in another town...)

Cuda
Cuda New Reader
3/17/12 9:37 a.m.

I was thinking about building something like this. Metal Brake

Woody
Woody UltimaDork
3/17/12 9:42 a.m.

I used a finger brake in seventh grade shop class and if I can find one of those for sale locally, I'd jump all over it.

And...this isn't a really critical part, so I just need to get it close.

ZOO
ZOO SuperDork
3/17/12 9:45 a.m.
Woody wrote:
Knurled wrote: What grade aluminum?

It is approximately the same grade as one would use when making a sign with the speed limit posted on it.

Photobucket

Thank you for that . . .

Dr. Hess
Dr. Hess UltimaDork
3/17/12 10:10 a.m.

So you're saying it's made from bullet resistant aluminum?

The0retical
The0retical Reader
3/17/12 10:17 a.m.

There's a whole explanation on radii I could post for you but if you just want to get it close and do not have access to a brake, get a 2x4 and a wood mallet. Cut and sand the 2x4 into the approximate shape and radius you want, place the line where you want the bend, center over it, and have at it. The wood mallet will prevent it from putting any serious dings in it and as long as you don't wail on it too much it will not stretch the aluminium. I've actually used that method to form ribs for a couple wings.

Do not heat up the metal because it will remove the heat treat if you heat it too much, cold bending is just fine.

Woody
Woody UltimaDork
3/17/12 10:20 a.m.
Dr. Hess wrote: So you're saying it's made from bullet resistant aluminum?

These things seem to attract bullets around here.

ditchdigger
ditchdigger Dork
3/17/12 10:22 a.m.
Dr. Hess wrote: It helps A LOT to anneal it. Get a black Sharpie marker. Scribble on the piece where you want it bent. Heat the area up with a torch until the marker lines fade. Let it cool slowly.

I swear by the acetylene soot method. Paint the area with just an acetylene flame then turn on the oxygen and burn the soot off. 6061 will be nice and soft after that. If you do the same thing and quench in water it will harden it a surprising amount.

akamcfly
akamcfly Reader
3/17/12 10:47 a.m.
Zomby woof wrote:
iceracer wrote:
akamcfly wrote: Grain direction is important when bending aluminum. the bend must be across the grain. Also T6 temper doesn't like to be bent - it's kinda brittle

Grain ?

Also, if it's cut properly, you can count the rings and tell how old the billet was.

http://www.engineersedge.com/sheet_metal.htm said: Minimum Bend Radii: The minimum bend radii data contained within the given charts are measured to the inside of the bend. The bend radii listed are standard minimum for manufacturing for aerospace and space applications. Commercial sheet metal radius are created with less concern for stresses created during forming and radii can approach zero (sharp internal corner) for many thin sheet metal gages. Grain Direction A "grain" is formed in metal in the direction in which the sheet is rolled at the mill. Be careful not to confuse this with surface finishes produced by grinding of other finishing operations. Grain direction is usually specified on stainless steel and other hard materials when it is necessary to maintain minimum bend radius or to control spring back on parts with large radius forms. The grain can be seen by viewing off the shelf sheet and noting the direction of visible lines running end to end.

I'm not as dumb as I look,

erohslc
erohslc HalfDork
3/17/12 10:57 a.m.

Success will depend on the alloy, and it's temper. Get one of the scrap pieces, not too wide, long and skinny works OK, and test it like this:
1) Remove paint, decals, etc, to bare metal, and then sand it to uniform finish (see step 5).
2) Clamp piece into a vise, or between two pieces of wood, leaving approx 1/2 the metal standing free.
3) Use another piece of wood placed against the free standing piece.
4) Use a hammer (BFH is best), and strike the wood from step 3 to make a sharp 90 degree bend.
5) Examine the outside of the bend carefully (this is why you need step 1), use a magnifier, and look for cracks or discolorations (much lighter color, or grainy surface).

If you see no cracks or discoloration, you will be fine. If you do see cracks, then it's probably an alloy that does not bend easily (2024, etc.).
If you see discoloration, then it may just be a hard temper of a malleable alloy (6061, etc).

Now try to straighten the bend back out, with your hands or BFH. Examine the inside of the bend area. If you see cracks or discoloration as above, well ,....
If the pieces cracks, well, there's your answer.

Permanantly changing to a softer temper depends quite a bit on the exact alloy, and the procedure can be rather involved:

http://www.mtbr.com/files/data/250.html
http://metalbashatorium.com/heat_treating_aluminium.htm

I've successfully used above process with a kiln to change 6061-T6 to T0, so I could form some tubes into tapered runners for an intake manifold.

But it's worthwhile as described in posts above to use a gas torch to heat the intended bend area, and see what happens.

You can experiment on scraps until you find the right technique for your metal, then do the real thing (I assume you don't want to go through the whole fab thing again).

Good luck, please let us know how it goes.

Carter

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