1" wide 1/4" thick Al flat stock rolling bender project?

Greetings All,
I've seen the images of the very nicely done three wheeled rolling
tubing bender in the drop box. I'd like to use something similar to
roll some 1" wide 1/4" thick Al flat stock the "Hard way" (aka
on-edge)
What I need to fabricate is a 1/4" thick ring of Aluminum that is 18"
ID and 20" OD. I need to make several of these, and cutting them from
sheet stock gets expensive quickly.
So I'm thinking all I need to do is change the rollers in the afore
mentioned tubing bender. The question is, what dimensions to make the
new rollers.
A) How deep will the square groove in the rollers need to be? Do I
need a full 1" radial recesses in the rollers to properly keep the
flat stock from wanting to twist during the bending process?
B) How wide should the grooves in the rollers be? Should all three
rollers have the same groove dimensions? I ask as the flat stock is
0.25" nominal thickness. I'm assuming that as I roll the flat stock,
the outside edge of the ring is probably going to stretch to a thinner
dimension, while the inside edge is compressed into a thicker
dimension....????
C) Assuming a 1" radial groove in each roller to fully support the
material as it is bent, what should my final outside diameter be for
each roller? The largest bar stock I have at the moment is only 2.5"
in diameter mild steel. If I use this to fabricate the rollers, I end
up with the inner dimension of the roller groove only being 0.5" in
diameter, will this be too small? I figure I'm going to use a 0.375"
shaft to support the bearings, which would not leave much material
between the shaft bore hole and the inner edge of the wheel groove...
D) Finally, using this setup and material, what would be the limits
for the smallest diameter ring I could fabricate?
Thank you for your time!
Take Care,
James Lerch
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(My telescope construction, Testing, and Coating site)
Press on: nothing in the world can take the place of perseverance.
Talent will not; nothing is more common than unsuccessful men with talent.
Genius will not; unrewarded genius is almost a proverb.
Education will not; the world is full of educated derelicts.
Persistence and determination alone are omnipotent.
Calvin Coolidge
Reply to
James Lerch
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Any chance of finding that size tubing??? Respectfully, Ron Moore
James Lerch wrote:
Reply to
Ron Moore
You didn't mention the sort of accuracy you wanted but I have done this with 1/8" x 1/2" to about 12" diameter. 1/4" x 1" would be harder but you should still be able to do it in a good bench vise. I made 3 quadrants in steel , 1 of these slightly less than the inner radius to allow for some spring back, and the other 2 with a radius to come to about 3/4 the depth of the material. The 2 pieces are placed either side of the radius former to hold the material alignment. Some clamp is required at the end of the quandrant to hold the material and then you just bend it into the groove, when done you unclamp it and move it around a bend another section. You can form quite a good circle this way. The formers could be made of wood but I had the steel handy.
James Lerch wrote:
Reply to
David Billington
I think I would make the machine pretty much as it is shown, and add supports to keep the aluminum vertical to the rollers. Ideally the supports would be more rollers, but I suspect you could get by with guides that don't rotate. Might want to line them with some plastic to prevent scoring the aluminum.
Dan
snipped-for-privacy@no.spam.tampabay.rr.com (James Lerch) wrote in message
Reply to
Dan Caster
The best is when the rollers conform to the shape of the material that is being bent. Getting that stock down to a 18" ID diameter will not be easy tho as the aluminum may start tearing.
-- Why isn't there an Ozone Hole at the NORTH Pole?
Reply to
Bob May
I'd consider the first one as Experimental...
If it starts cracking, the only recourse would be to anneal the aluminum bar stock with a torch or an oven after each pass or two through the rollers.
-->--
Reply to
Bruce L. Bergman
Another way to consider doing this would be to fabricate a rolling mill with tapered gap between the rolls. As you roll the ring the way you are talking, the outer edge is going to get thinner anyway, this would just take advantage, but might help keep the tearing down by forcing the thinning to be equal throughout. jk
Reply to
jk
Very interesting idea! I think I can fabricate such a device...
Take Care, James Lerch
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(My telescope construction, Testing, and Coating site)
Press on: nothing in the world can take the place of perseverance. Talent will not; nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts. Persistence and determination alone are omnipotent. Calvin Coolidge
Reply to
James Lerch
I have done this a lot- but I have used storebought tools that I actually paid cash money for. I use two different tools to do this type of thing- A hossfeld bender- hossfeld makes flat bar edge bending dies for their angle iron flange in die setup, and it works quite well for exactly this sort of job. It actually uses a wedge configuration that tightens down on the metal the harder you pull, so you can bend flat bar the hard way in radiuses from about 6" to 36" or larger. Of course, a hossfeld tooled up this way will run about $1500, and in this age of harbor freight, few people want to spend that. But a hossfeld will do this quite easily, repeatably, and to fixed radiuses. Along with doing about 5 million other things.
The other tool I use to do this is my CP-40 Curvatricci from Eagle-
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powered section roll designed to do just this sort of thing. They use a series of multipart dies that bolt onto a shaft, rather than one piece tooling with a slot milled in it. That way, you can stack spacers up to fit any size of flat bar. I have spacers ranging from 16ga up to about 3/4" thick, in many different sizes, so I can always get a nice snug fit on most any thickness bar. I like to have the flat bar just slide thru the die- a few thousandths clearance. But if it sticks, I can always add a spacer. The outer dies, shaped like big donuts, are about 6" in diameter and 1" thick, while the spacers are about 2 1/2" od. This means a 1" flat bar is completely supported in all three dies. The radius you can bend would depend on the up and down travel of your central roller, and the center spacing of your two lower rolls. A machine designed to get very tight radius on small bar might be less useful when you are rolling 2" pipe, so design parameter vary depending on machine size- if you look on their website, you will see the spacing, and hence the tightness of radius possible, is much closer on the little tiny machines than it is on the ones made to roll 6" pipe. It takes a fair amount of power to roll large flat bar this way- I do a lot of stainless, in 3/8" and 1/2" thicknesses. But you could probably do this small aluminum with a hand crank machine. Multiple passes will probably be required, to sneak up on your radius, as trying to bend the aluminum all in one pass would undoubtedly crack it. This would make it a little tougher to get matching circles, but certainly not impossible- you just check em against a template, and roll again, until you get there. My curvatricci has a digital readout, so theoretically you can return to the same setting with every new piece of material, and this works pretty well, although even within the same mill run, there are variations in how a piece of metal will bend.
Now with a hossfeld, you just put on the 9" radius die, and you pull an 18" circle every time.
Reply to
Ries
Reis,
On your dies with wedge, are all three rollers identical, or do only the outside radius rollers have the wedge?
Any chance you could post / email some pictures of the various dies?
Take Care, James Lerch
formatting link
(My telescope construction, Testing, and Coating site)
Press on: nothing in the world can take the place of perseverance. Talent will not; nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts. Persistence and determination alone are omnipotent. Calvin Coolidge
Reply to
James Lerch

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