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.
Your a smart and resourceful cookie, I really like articles like this and people like yourself. This is the embodiment of the true Hot Rodder spirit.
Yeah, Ditto Brother
i worked in an exhaust and muffler shop for 4 or 5 years as a young fella,good experience!
I'm not sure what the home-made header experts would say but when I built my Patriots I did all my welding on the inside of the flange (head side)...and thus no welding gap was required at the front. One of my primary reasons for doing this was that any welds on the outside of the flange would be quite difficult to get at with a grinder to clean up and smooth out. This is not really a problem for TM since he is a much more competent welder and could proudly leave his welds untouched for the world to see. Mine...um, not so pretty.
So this is mostly just a suggestion/option for the other newbie welders who might want to try this out.
That's the way I do it with the exception of a small tack weld on each side on the outside. Not saying that the tack welds are necessary, just that I reasoned that if the pipe had some support on the outside it would be less likely to crack at the weld because of the two-point support. Just a thought. :)
I plan on welding it from the back side. Right now I just have some tacks on the front, but a tight fit means I can run a TIG bead around the flange.
Nice work, t.M. How's life in the self employed world treating you? I plan on winning the lottery next week, I'd like to hire you for a year or two to build me some race toys. :D Dan
Really nice fit man!
Listen I have been thinking.... If you changed your profile to say your age is 45 or 50 it would make me and a lot of other folks feel better about themselves. :embarrass
Just a friendly suggestion. :boxing:
JK :thumbup: :thumbup: ;)
Thanks Dinger. I am enjoying it so far. Its got it's frustrating days like any job, but for the most part I am really having fun. And that weighs out even the worst of days.
Damn Seth, you are everywhere
Nice write up
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