Curved Tube Construction.

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JetSet
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Curved Tube Construction.

Post by JetSet » Wed Jun 08, 2005 10:31 pm

Hello.

With regards to getting a 180 degree bend in a tube (3 inch diameter), what do you think would be the best way to go about it?

Being on the tinyest budget you've ever seen, buying a mandrel drawn U bend in 321ss, the 'ideal option' is out of the question, as would making a primative pressure bender (would this even be feasible with a 3 inch diameter tube?!) and bending my own...


There are two options that i can think of;

#1. Rolling a tube, with the same length of the outer circumference of the bend (apprx 28 inches). The inner radius would be around 18 inches.

Looking at the tube straight down on the tube, lots (say 10), of triangles would be cut out of the tube (cutting all of the way through the tube). The triangles would have a 1 inch base (to remove length from the side that needs to be shorter). The pieces could then be joined together again to make a nice bend (roughly a bend :D ).

#2. Very similar to the first, but make a net for each section of tube, and join them together.


I am thinking #1 is the way to go, however I would like other's advise if you can give it please :D Its for a lockwood, which apparently isnt too fussy about these things (however i will obviously try to make a nice job of it regardless 8) ). Also, where would be the best place for the tube seam? Inside edge?

Alternatively - should I be using a different method altogether?

Thank You!
:-)

evildrome
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re: Curved Tube Construction.

Post by evildrome » Wed Jun 08, 2005 11:30 pm

If weight is not a factor but cash is, make it out of 14 or 12 gauge mild steel. The metal price will be reduced to the point where you can afford one 180 or 2 X 90 degree bends.

Cheers,

Wilson.

Bruno Ogorelec
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re: Curved Tube Construction.

Post by Bruno Ogorelec » Thu Jun 09, 2005 8:53 am

You can also fabricate a square-section U-bend out of sheet steel and mold/bang out/force/curse the square ends into round to join them with pipes. It's been done even by very serious engine outfits, like SNECMA. It will work just as well as the round-section bend, if not better.

JetSet
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re: Curved Tube Construction.

Post by JetSet » Thu Jun 09, 2005 9:48 am

Thanks.

I haddnt thought of square section curve. That should be easier.
mold/bang out/force/curse the square ends
Now that something I know how to do!!

Mike Everman
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re: Curved Tube Construction.

Post by Mike Everman » Thu Jun 09, 2005 2:11 pm

Through an industrial supply house like McMaster-Carr you can get "sanitary tube and fittings", 304SS.
Thin walled 90 deg bends can be had cheaply, like a 2" dia, .065 wall with a 3" radius of curvature is $9.50 US. So $20 gets you a perfect 180 with a tight bend. Much tighter than any mandrel bent exhaust piece you might buy.
Mike
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