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Old 06-09-2016, 15:11   #1
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Bending 316L Stainless tube

I am going to fab up a solar arch/davit out of 32mmx1.5mm wall.
Will that bent ok at a 12 to 15" radii? Without rippling.
Ta for any tips.
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Old 06-09-2016, 15:21   #2
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Re: Bending 31L Stainless tube

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Originally Posted by lateral View Post
I am going to fab up a solar arch/davit out of 32mmx1.5mm wall.
Will that bent ok at a 12 to 15" radii? Without rippling.
Ta for any tips.
Max. you can bent with simple plumbing pipe bender tools is 22x1.5 and 25x1.5 in 316 quality.
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Old 06-09-2016, 15:23   #3
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Re: Bending 31L Stainless tube

What about hydraulic? Will it ripple?
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Old 06-09-2016, 15:34   #4
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Re: Bending 31L Stainless tube

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Originally Posted by lateral View Post
What about hydraulic? Will it ripple?
For this size of Stainless tube you need access to a Stainless tube bender to avoid ripples. The hydraulic ones for black steel will ripple the tube and not have mm dyes.
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Old 07-09-2016, 08:59   #5
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Re: Bending 31L Stainless tube

Look on-line for a "Bend-Rite" tubing bender through Marine Canvas Institute.

It work for me on tubing for solar panels and bimini frames.

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Old 07-09-2016, 09:02   #6
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Re: Bending 31L Stainless tube

Sounds crazy, but filling it with sand before bending may help, plug the ends of course.
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Old 07-09-2016, 09:19   #7
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Re: Bending 31L Stainless tube

31L bends like overdone spaghetti compared to 316L
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Old 07-09-2016, 09:22   #8
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Re: Bending 31L Stainless tube

The packing it with Sand prevents the SS from kinking ! Just do it if it kinks you need another SS pipe ! The sand stops the inside gives it resistance to accept sharp bends. Lee Nicholas / Fla
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Old 07-09-2016, 09:28   #9
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Re: Bending 31L Stainless tube

Quote:
Originally Posted by lateral View Post
I am going to fab up a solar arch/davit out of 32mmx1.5mm wall.
Will that bent ok at a 12 to 15" radii? Without rippling.
Ta for any tips.
I have been bending this same material for a long time in my business and have made several parts for friends and myself out of polished 1" X .054 wall tubing with no problems or rippling using a hand bender with standard and custom dies.

Including arches and pulpits. see the pics of the bender and finished parts.

this wall thickness (.054" (1.5mm)) bends well. I haven't tried in a conduit bender and would expect that it would very difficult due to the strength required.

on my bender I have a long handle (not shown) that fits in the end that gives me the leverage necessary to make the bends. it makes very nice smooth bends.

(sorry that the pics are rotated, they weren't when I upload them, and I cant figure out how to rotate them in side CF)
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Old 07-09-2016, 09:41   #10
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Re: Bending 316L Stainless tube

You need a mandrel tube bender of some description rather than a pipe bender. There are a couple of reasons for this. Firstly, tube and pipe outside diameters aren't specified the same (tube diameter is outside diameter and pipe is nominal bore) which can make tube a poor fit in a pipe bender die, adding to difficulty. Having said that, I've used the sand filled method on a pipe bender and acheived good results but it is a pain to do. The shallower the bend, the easier the job. For my next fast approaching tube project I'm just going to buy weldable bends and use them whenever possible.

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Old 07-09-2016, 09:42   #11
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Re: Bending 31L Stainless tube

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Originally Posted by a64pilot View Post
Sounds crazy, but filling it with sand before bending may help, plug the ends of course.
May sound crazy but isn't. It was standard practice for thin wall. I guess commercially today they have other methods.
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Old 07-09-2016, 10:00   #12
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Re: Bending 31L Stainless tube

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I guess commercially today they have other methods.

I saw one high tech bending operation. The bend looked terrible until they pulled a ball bearing looking mandrel thing back through the inside and tube came out perfect.
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Old 07-09-2016, 12:22   #13
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Re: Bending 31L Stainless tube

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I saw one high tech bending operation. The bend looked terrible until they pulled a ball bearing looking mandrel thing back through the inside and tube came out perfect.
Maybe someone in the industry can enlighten us. Last I knew it was a mandrel with a hydraulic rolling mandrel making the bend. Feel sure it has progressed from that? I guess the sand worked back when, to keep the tubing from crinkling.

Today computer controlled machining is unbelievable.
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Old 07-09-2016, 12:36   #14
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Re: Bending 316L Stainless tube

Quote:
Originally Posted by lateral View Post
I am going to fab up a solar arch/davit out of 32mmx1.5mm wall.
Will that bent ok at a 12 to 15" radii? Without rippling.
Ta for any tips.
That's a generous radius, 10x plus....should bend fine. Pretty thick wall too. How many degree bend though?
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Old 07-09-2016, 12:40   #15
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Re: Bending 31L Stainless tube

Quote:
Originally Posted by Cadence View Post
Maybe someone in the industry can enlighten us. Last I knew it was a mandrel with a hydraulic rolling mandrel making the bend. Feel sure it has progressed from that? I guess the sand worked back when, to keep the tubing from crinkling.

Today computer controlled machining is unbelievable.
Yeah, I've bought a few machines for aerospace work. It's all mandrel bending. We even did some .025 wall titanium bends down to a 1.5 D radius! ... in diameters like 3" and bigger...
The bronze ball mandrel supports the material from wrinkling and a wiper die wipes the tube around a bend block. The ball mandrels must be in precisely the right place throughout the bend.
I've not seen a system that pulls the ball thru after bending to remove wrinkles. In sheet metal, the material has to go somewhere, it either changes shape or gets thicker. Pulling a ball thru would create stresses and change the shape I would think, but there is a lot of new stuff so maybe so....
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