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19662
03-17-2010, 11:42 AM
On occaision I run into needed to do this...sometimes I get it but more often I don't!!! Mostly I need to put a curve on a piece of 1/2" round 6061(not a tight curve about about the radius of 20"). I use low heat with the torch. 9 times outta 10 it cracks on me. Any ideas?????

4sfed
03-17-2010, 12:46 PM
On occaision I run into needed to do this...sometimes I get it but more often I don't!!! Mostly I need to put a curve on a piece of 1/2" round 6061(not a tight curve about about the radius of 20"). I use low heat with the torch. 9 times outta 10 it cracks on me. Any ideas?????

You should be able to do that cold, but you can heat it up to 350° F to temporarily increase elongation to more than 20%. Higher temperatures or long times will overage the material and decrease the strength.

Jim

zapster
03-17-2010, 12:53 PM
On occaision I run into needed to do this...sometimes I get it but more often I don't!!! Mostly I need to put a curve on a piece of 1/2" round 6061(not a tight curve about about the radius of 20"). I use low heat with the torch. 9 times outta 10 it cracks on me. Any ideas?????

You need to anneal the material first..
Take the Oxy.- Acc. torch and with straight Acc. blacken the piece..
Turn on the Oxy to gat a good flame..

Heat until the blackness goes away then quench in COLD water until cool..

Bend away.
Problem solved..

...zap!

makoman1860
03-17-2010, 01:15 PM
If your concerned about strength, dont anneal it. If not, pick a different alloy that is more ductile like 3003 or 1100 and save the trouble of annealing, sterength wont be that far off from annealed 6061.

Rojodiablo
03-17-2010, 07:42 PM
If your concerned about strength, dont anneal it. If not, pick a different alloy that is more ductile like 3003 or 1100 and save the trouble of annealing, sterength wont be that far off from annealed 6061.

I'd rather roll bend 5052, or 5286 for this application. The brittleness of the bent 6061 can not be looked over; you are looking for some stress fracturing. Zap's method of annealing is correct; thing is, you just took the strength down to 5052 or less. Not to say it won't be strong; it will even work harden back up a bit when bent. FWIW, I rather like Makoman's take on this for sheet work. When you form something, the strength comes from the overal build, not just the one part. With this in mind, the 5052 is a good choice and readily available.

castweld
03-17-2010, 10:21 PM
I've bent 1/2 6061 to 3" radius cold in shop outfitters bender. 20" should be easy cold. If you are bending to a form start with longer than needed stock and use cheater. Use form with tighter radius to counter spring back.
Peter

4sfed
03-17-2010, 10:47 PM
I'd rather roll bend 5052, or 5286 for this application. When you form something, the strength comes from the overal build, not just the one part. With this in mind, the 5052 is a good choice and readily available.

5052 and 5086 (I suspect a typo) are typically sheet products. It's uncommon to find bar stock in either alloy . . . at least with my suppliers. :confused:


I've bent 1/2 6061 to 3" radius cold in shop outfitters bender. 20" should be easy cold.

Like castweld, I think 6061 T6 should be easy to form to a 20" radius. I'm hoping 19662 will tell us if he's tried that.

Jim

Rojodiablo
03-17-2010, 11:07 PM
5052 and 5086 (I suspect a typo) are typically sheet products. It's uncommon to find bar stock in either alloy . . . at least with my suppliers. :confused:



Like castweld, I think 6061 T6 should be easy to form to a 20" radius. I'm hoping 19662 will tell us if he's tried that.

Jim
You're right. Typo.:rolleyes:

Jack Olsen
03-17-2010, 11:19 PM
Roller bender.

19662
03-18-2010, 01:47 PM
I may have been off with radius thing...but nonetheless I need to incorporate heat as I have no bender in this shop. The strength isn't an issue either but I'm not sure a fella could get 3003 in a round bar and in this application it wouldn't last if I used it.

castweld
03-18-2010, 10:28 PM
I bent this 1/2 round bar some time back, it was done cold (room temp). Diameter 3.5".
Leverage is your friend.
Peter

19662
03-19-2010, 12:24 PM
I bent this 1/2 round bar some time back, it was done cold (room temp). Diameter 3.5".
Leverage is your friend.
Peter

I dont doubt you for one minute castweld but....really?

castweld
03-19-2010, 11:46 PM
I dont doubt you for one minute castweld but....really?

Really.
Peter

rode2rouen
03-20-2010, 01:38 PM
The test pretzel in the pic is 3/4" X .065" wall 6061 T6 tube. No heat, no cracking. Bend radius is 2.5".
You ought to search "roll bender", there have been a number of shop built, low buck units shown on the forum that would do the 20" radius you need.


Rex

http://i721.photobucket.com/albums/ww216/bjorn_toulouse/Pretzel.jpg