Bob May wrote:
Got a need to bend some aluminum bar stock into some circles. The stock is
1/2x1 and I need to bend the hard way into a diameter of about 14". Talked
to a guy at the blacksmithing shop where I'd expect that they'd be able to
do this in steel and the guy said good luck! He can do smaller stuff into
wagon wheels or hot bend to any desired shape but not in aluminum.
I'd figured that he'd have a 3 roll setup to do and diameter that he wanted
to do but apparently, he never did such. He did mention that he's tried
doing some smaller diameter work with his wagon wheel roller but it quickly
became impossible as the metal wouldn't feed in the roll.
Am I trying something impossible or is it just that blacksmithes don't
really do such work as they have other ways to do so in steel?
I'm also going to have to do another ring of 1"x3" the easy way. Both rings
will be welded into a continous circle.
Would it be better to grab a big chunck of plate and mill out the excess?
No. Depending on the alloy, of course, this should be doable.
If it was 1/8 x 1" you might need some special rollers with flanges to
prevent the bar from trying to roll over and bend the "easy" way.
I think you may be able to do the 1/2 x 1" bar without flanges,
but it will become slightly twisted in the process. 3003 is very
amenable to bending, and 2024-T6 will probably show a lot of fine
cracking on the outer side of the bend. Other alloys would probably
be in between.

it will still take a pretty stout roller to bend 1" bar the hard way.
You will need to make the ring a bit long, as the last couple inches
won't get bent by the rollers. Put in just a little bend each pass
through the rollers, and keep running it through. When the ring
closes, it will be difficult to get one end in the roller when the
overlapping far end is in the way. I'm not sure how to deal with
this except by making the thing a helix. Then, you can cut the ends
and flatten it to a ring.

The rollers that Harbor Freight and other hobby-level tool sellers have
will definitely not handle the 1 x 3" bar, even the easy way. You
need a serious roller, or a press brake to do material like that.

Machining that out of a 3" thick aluminum plate will not only be a
major machining job, the stock will cost a fortune.

Jon