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Old 11-16-2008, 08:08 PM
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How To: Press Forming Exhaust Tubing

I got my header flange from Hot Rod Chassis last night and it gave me an idea. I want to use 1.5" tube for my header, because thats what I can bend, and it matches my cones from Cone Engineering. As you can see, it doesn't really fit.

So last night I though I might be able to make a die to press the tube over and force it to take the form I wanted. I found an aluminum square that was close to the size I needed, so I ground it down real quick and tried it with a piece of copper pipe. It made a pretty rough square, and galled the aluminum a bit. But I now know it could work, and it also showed me what kind of space I needed to leave for the tube to form over and provide a good gap.

I found I needed to leave about 3/32" between the die and the inside of the flange for the tube to fit well. So this morning I started building a die out of steel. It needed to be 1 3/16" wide on one side, and 1 5/8" on the other. Not having any large blocks of steel, I cut three pieces of steel 1 5/8" wide at the bottom and 1 1/4" wide at the top. I used two pieces of 1/2" plate and one piece of 3/16".

I cut them larger than I needed, because I'm not that great with the plasma on thicker stuff, and needed them to be smooth. So I got out the 9" grinder and went to town until they where all roughly the same size.

I then welded them together with the 3/16" plate in the center of the two thicker plates.

I then proceeded to grind the blocks until they all matched. Then I raduised the corners to match the die as best I could, and did some finish grinding with a 4.5" grinder and a 120 grit disc.

I made sure it fit inside the flange well, and adjusted it as needed until I was satisfied.

Now time to test it out. I coated it in some low heat lithium grease to help the process, and make it easier to remove.

I then pressed the other side of that same copper pipe onto the die.

The die was easy to remove with a hammer and a brass punch. It left the tube looking like this.

I tested the fit, and I was happy. It fits very snug on the back side of the flange, and left a weldable gap at the front. I think if I press the tube on just a little farther I can tighten the gap at the top so I can TIG weld it.

I received my order of steel, and tried it with some 1.5" .063 wall tube.
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