Bending oval stainless tubing into spiral: how???

[MetalMan23]

As the title suggests, I'm wondering how I can bend oval stainless tubing into a tight spiral, here's a pic of a similar tubing, and the general design of the railing I'm making, the oval stainless tubing will be the cap rail, and be continuous from the top all the way to the bottom of the flights or stairs, there's 4 flights,

The sketch shows the general layout of the railing, although the actual style will be different.

Any ideas?

Heat and bend? It's a pretty tight radius,, kerf cut and weld (and weld and weld and weld) and grind down?? I could achieve a tighter raduis by kerf cutting and welding but it mgith appear slightly segmented,

I don't think I can heat up and twist that tubing tight enough without serious distortion and it losing its shape.


Oh here's an idea, what about filling it with sand, then heating it up, and forming it, would the sand stop the tubing from distorting?


Ornwoudl the sand melt inside when the stainless got to around 2000 degrees lol



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[Bls repair]

[tapwelder]

Chicago Roll is an option, also. The likely can produce a single piece, at least long pieces and the pitch.

Seems like a lot of work if you keep it in shop.

[CrookedRoads]

The sand doesn't work but I have stuffed aluminum pipe or round rod inside of stainless tube to keep them from distorting and that works. The contract benders are pretty expensive unless your doing a large quantity, maybe RB Wagner.

[MetalMan23]

The other option would be to use solid bar, and grind the edges and hope it matches? That seems like a lot of work.

There's only 3 bends

Approximately 20" each

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[tapwelder]

I found Chicago roll to be reasonable, your profile might influence price. If it were mild steel it would be easier in many aspects.

Perhaps bends sections are available .

[walker]

I would try it with the sand. Wouldn’t need to be 2000 degrees, 800-900 would do it I would think. If it proves to be a problem, consider cutting the bends out of two pieces of flatbar and welding with a spacer, or just out of flat plate and hand finishing the edges. You might be able to roll a pice and use it for the turns, or stack two pieces and bend it in a square tube die. Just throwing out ideas, hopefully one will sound promising.

[tapwelder]

Perhaps, you could burn plate and weld tubing. Just seems like a lot of cleanup?

Or burn the solid and bevel edges.

[smithdoor]

I have only known of companies filling with sand then bending.

Since I was not in that line work I never try bending with sand. But seen large pipe and rectangle tubing bent using sand fill.

Dave

As the title suggests, I'm wondering how I can bend oval stainless tubing into a tight spiral, here's a pic of a similar tubing, and the general design of the railing I'm making, the oval stainless tubing will be the cap rail, and be continuous from the top all the way to the bottom of the flights or stairs, there's 4 flights,

The sketch shows the general layout of the railing, although the actual style will be different.

Any ideas?

Heat and bend? It's a pretty tight radius,, kerf cut and weld (and weld and weld and weld) and grind down?? I could achieve a tighter raduis by kerf cutting and welding but it mgith appear slightly segmented,

I don't think I can heat up and twist that tubing tight enough without serious distortion and it losing its shape.


Oh here's an idea, what about filling it with sand, then heating it up, and forming it, would the sand stop the tubing from distorting?


Ornwoudl the sand melt inside when the stainless got to around 2000 degrees lol



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[smithdoor]

FYI heat the inside radius. The out side will get very thin with heat.

Dave

As the title suggests, I'm wondering how I can bend oval stainless tubing into a tight spiral, here's a pic of a similar tubing, and the general design of the railing I'm making, the oval stainless tubing will be the cap rail, and be continuous from the top all the way to the bottom of the flights or stairs, there's 4 flights,

The sketch shows the general layout of the railing, although the actual style will be different.

Any ideas?

Heat and bend? It's a pretty tight radius,, kerf cut and weld (and weld and weld and weld) and grind down?? I could achieve a tighter raduis by kerf cutting and welding but it mgith appear slightly segmented,

I don't think I can heat up and twist that tubing tight enough without serious distortion and it losing its shape.


Oh here's an idea, what about filling it with sand, then heating it up, and forming it, would the sand stop the tubing from distorting?


Ornwoudl the sand melt inside when the stainless got to around 2000 degrees lol



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[MetalMan23]

Does anybody have experience trying to bend tubing shaped like this with heat?

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[Welder Dave]

I think you'd need some dies the same as if it was square tubing. Filling with sand may work but the sand has to completely dry and then packed tightly in the tube and the ends capped so the sand stays put.

[William McCormick]

As the title suggests, I'm wondering how I can bend oval stainless tubing into a tight spiral, here's a pic of a similar tubing, and the general design of the railing I'm making, the oval stainless tubing will be the cap rail, and be continuous from the top all the way to the bottom of the flights or stairs, there's 4 flights,

The sketch shows the general layout of the railing, although the actual style will be different.


Any ideas?

Heat and bend? It's a pretty tight radius,, kerf cut and weld (and weld and weld and weld) and grind down?? I could achieve a tighter raduis by kerf cutting and welding but it mgith appear slightly segmented,

I don't think I can heat up and twist that tubing tight enough without serious distortion and it losing its shape.


Oh here's an idea, what about filling it with sand, then heating it up, and forming it, would the sand stop the tubing from distorting?


Ornwoudl the sand melt inside when the stainless got to around 2000 degrees lol



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You have to cold work it, or yellow hot work it, there is no in-between.

If you filled it with a solid aluminum bar as was mentioned that would keep it pretty nice. And then just put it through the Hosfeld or whatever you are going to try to bend it with. I used to make Teflon dies to bend aluminum and brass handrails sideways. I would just grab a scrap block of aluminum hollow it out on the table saw and put in a Teflon liner. I almost cut off a finger doing something like that on the Hosfeld, with two guys working on it simultaneously I was the holder, haha.

If you distort stainless steel while it is red hot it will develop visible stress cracks, especially if you use any hammer type forming. You can warm it so it is not 50 degrees, but you cannot turn it red and work it. I would probably go with a solid stainless steel flat bar it is cheap, get a couple twelve footers and just bend them and form them and just round the edges with a carborundum wheel or even 24 grit sanding discs on the right angle grinder. Then I would use a high-speed angle grinder with 3" roloc discs 40 grit to smooth out the 24 grit marks, and then 80 to remove the 40 grit marks. You need bee's wax or don't bother it makes the discs cut through stainless like it is wood. You want the metal hot so the wax melts. Then you have so many options. It depends on the finish you want. You could sand with orbital or vibrating sanders, but it is a slow and tedious thing. They make some wheels now that are supposed to do a good job on lightly scratched material, and then you need polishing wheels and rouge, which you need no matter what you are doing if it is a mirror finish. If it is brushed it is easy you just sand it by hand in the direction of the grain and you are done sanding then I just go with the grain with a nylon pad by hand that takes off any hooks the sandpaper creates. I usually use 220 grit for the brush look. On large flat pieces, I use an autobody planer sander to make brush marks.

Sincerely,

William McCormick

[smithdoor]

I wish had any experience

I have only did round pipe using heating on inside bend. It was repair work too and you can get away with more.
Most my experience was making straight again.

Note they do this type bending in Hobbies

Dave

Does anybody have experience trying to bend tubing shaped like this with heat?

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[CrookedRoads]

Once again sand does not work, it will distort right along with the tube. And this shape will try to go round when you bend it so you will need some type of dies to keep the profile.

[tapwelder]

Low temp melting metals might work as a filler? Somebody gave me some bismuth alloy it melted at sub 200 degrees. I think it expands as it cools, I recall it breaking a beaker. If it works in would be reusable.

I have made dies of delrin. Pretty easy to turn.

[MetalMan23]

I could fill it with aluminum , that melts at around 1200

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[MetalMan23]

Or maybe cold forming then annealing cold forming then annealing and repeat until it's formed?

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[MetalMan23]

Called sharpe, they said they don't have any dies at all for that shape, no surprise

He suggested doing the solid bar,

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[smithdoor]

I would make my own dies and use my own press.

Dave

Called sharpe, they said they don't have any dies at all for that shape, no surprise

He suggested doing the solid bar,

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[mrmikey]

Maybe two pieces of round tubing or pipe the correct diameter to give you the radius and flat bar joining them?................Mike

[ezduzit]

Maybe two pieces of round tubing or pipe the correct diameter to give you the radius and flat bar joining them?................Mike

I think you're onto the right approach. The curved section could be fabricated from two tubes, then fixtured and sheeted together.

[Brett]

I'm thinking I would get to rolled in solid , without shaping it , them grind and linish to shape .
I think its too tight a radius to get a good result with that wall thickness.
It will increase the chances of the roller having a die , but in solid you will probably have to send it away.
Labour intensive but probably less than adding a tube to the side . Possibly a better finish .

[MetalMan23]

I found some half round bar from Mcmaster Carr, also online metals has it, I'm gonna get some 1.5" solid bar and weld this half round on each side, will make the same profile, I may end up doing it for the straight sections too, just because of logistical issues in trying to get the oval tubing in time.

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[MetalMan23]

I'm thinking of heating the flatbar in the forge, twisting/bending it into the proper shape, I rolled this plate to the required radius, and then heating the half round and welding it on as I go, matching the core of the solid bar, it'll probably take a fusion weld, minimal filler rod, then just smooth it out with the sanding pad.

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