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Author: Subject: Making round tube oval-ish
DIY Si

posted on 23/8/12 at 09:51 AM Reply With Quote
Making round tube oval-ish

Morning all.

I've been having a look at the beginnings of my exhausts, and have a slight problem. The original cad file for the flanges was designed for 1 5/8" tube, but that's a bit big for my engine, so I got a mate to re-draw the ports a little smaller, with an ID that we thought would match the OD of the 1.5" tube I'm using. However, my first attempt at flattening the round tube out to match has produced this result, and I suspect the ports could have done with being a fraction smaller:



Due to having to flatten it in my vice, the end of the tube is tapered, which doesn't help. But I can't think of another simple way of doing this.

So how can I best go about making the two shapes match? I can't afford to get the flanges re-done as number 1 son has just arrived, and money's a bit tight. The first thought I had, given that I'll be MIG welding the lot together is to put a thickish bead down and then grind the bit of the tube within the flange back to shape. Not the best idea I know, but it'll probably only cost me time. I'd rather there be a sensible way of making the shapes match though!





“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
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Minicooper

posted on 23/8/12 at 09:58 AM Reply With Quote
I would weld were they touch then use the heat to form and panel beat the lip tighter around the edge, once you have some heat in it, it's very easy to form the metal

Cheers
David

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liam.mccaffrey

posted on 23/8/12 at 10:08 AM Reply With Quote
I saw an amazing video of exactly this technique a few years ago i saved it on my generic satellite recording device, but it went south and we lost it.
The program was wreck rescue presented by Mark "Is Born" Evans and it was the edition where they restored an old single seater Elver?? race car.

Basically they put the flange in the vice and with the pipe tacked in one place they put a piece of 3/4" solid bar inside the pipe and gently hammered the bar against the inside of the pipe to form it to the flange profile and tacked as they went. Voila perfect fit.

When you see something like this, its like magic how well it works.





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rb968

posted on 23/8/12 at 10:19 AM Reply With Quote
I remembered exactly the same thing.......

Think its in here somewhere.


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loggyboy

posted on 23/8/12 at 10:32 AM Reply With Quote
http://www.youtube.com/watch?v=1lfyDK4j5TQ&feature=player_embedded#t=719s





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DIY Si

posted on 23/8/12 at 10:49 AM Reply With Quote
Many thanks, I hadn't though of doing it that way. Looks much easier than I expected too, as even I can heat a tube and hit it with a hammer, so I've got a fair chance of getting it right!!





“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War

My new blog: http://spritecave.blogspot.co.uk/

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liam.mccaffrey

posted on 23/8/12 at 10:57 AM Reply With Quote
im not sure you'd even need to heat it?! Best of luck let us know how you get on





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Fred W B

posted on 23/8/12 at 11:18 AM Reply With Quote
If you can find a piece of solid material a bit bigger then the port size, dress it to the shape of the port with an angle grinder and flex back. Put a bit of a taper on it. Hammer or press the resultant shape into the pipes, or use it as a dolly.


cheers

Fred W B





You can do it quickly. You can do it cheap. You can do it right. – Pick any two.

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DIY Si

posted on 23/8/12 at 11:20 AM Reply With Quote
quote:
Originally posted by Fred W B
If you can find a piece of solid material a bit bigger then the port size, dress it to the shape of the port with an angle grinder and flex back. Put a bit of a taper on it. Hammer or press the resultant shape into the pipes, or use it as a dolly.


cheers

Fred W B


That was my other thought, but the only things I have that might do are bits of soft wood, and I don't think they'd be up to the task. I'll give the first method a try and see how I get on.





“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War

My new blog: http://spritecave.blogspot.co.uk/

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FuryRebuild

posted on 23/8/12 at 11:45 AM Reply With Quote
You need to watch this series: http://youtu.be/j9knDsi-td8

These guys are brilliant and show you just how the experts do it. it's an hour very well spent.

Mark





When all you have is a hammer, everything around you is a nail.

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loggyboy

posted on 23/8/12 at 12:07 PM Reply With Quote
quote:
Originally posted by FuryRebuild
You need to watch this series: http://youtu.be/j9knDsi-td8

These guys are brilliant and show you just how the experts do it. it's an hour very well spent.

Mark

Superb set of vids, and im only half way thru the 2nd vid!





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FuryRebuild

posted on 23/8/12 at 12:34 PM Reply With Quote
It was watching that set that gave me the confidence to make my own exhaust in stainless.





When all you have is a hammer, everything around you is a nail.

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