TECH - Press Forming Tube for Exhaust Flange

Kind of last minute for Tech Week, and I know I won't win, but 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 one 3/16".


I cut them larger than I needed, because I'm not that great with the plasma, 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 didn't have any thin wall steel to test this with, but I wanted to post it any way. Steel gets delivered here next Monday so I will report back when I try it in steel.

 

Looks great! Way to use the old noggin. That could come in handy for a lot of us that don't have the fancy shmancy machines at home. Thanks for the tech.

 

That's a usable tech piece that many of us will be saving, thanks.

 

Very nice, Thanks!

 

Good tech MINI, thanks for sharin.

 

Very cool, hows about a demo of an actual exhaust pipe. How easy is it to get the die out of the pipe? Sure a 6 inch piece of brass is easy, but what about something you would really make a primary out of..

don't get me wrong, I aint knockin it, I havent made anything that cool... Just wondering

 

Nice work.

 

Nice job. Now I need to make one to do the nailhead rectangular port.

Charlie

 

Very nice . . . but I'm wondering how you will use the press to swage the end of a U-bend?

 

Drill and tap a hole in the base of the form, now it can be removed with a slide hammer.

How you're gonna hold the pipe in the press......no idea.

(edit- maybe you're gonna hold it in the press by tack welding the U bend to something stable)

Awesome tech, I've got the same problem coming up and it's great to see such a clean solution.

 

Cool deal...I have to do some ovals and I'm going to use your idea...thanks man.

 

First Your idea is cool and obviously will work... And I'm not trying to hijack your post.

But the questions got me to thinking. What about curved pieces of tubing. I know there is probably a tool like this out there already. Probably at every muffler shop but I think this could be homemade like yours is.

I've got too many irons in the fire to do this right now.... so I offer the design up. Hope someone builds one- maybe for the next tech week.

Thanks, Dan

 

Like I said, when Monday comes I will do it with steel and come back with the results. All I have right now is .120 wall steel.

The die came out of the copper easily. I held it in my hand and hit it with a brass punch and it popped out. I assume it will take more force to remove it from steel, but I plan on tapping the bottom so I have something to grab it by in the vice.

I thought about that. I just plan on forming a short straight piece, and TIG welding my bend in place.

I couldn't come up with a solution to press something into a bend without hurting the bend, or setting the die in crooked.

 

It should work fine on tube. We have alot of similar dies for forming on a press. If it does stick take a small hammer and tap around the tube on the big end as it the only spot the tube will be gripping the die. On some of our swedge dies we'll weld a bead around the end of the die were the tube stops to form a slight flair. This will release the tube from the die.
Weld the die to a bench and beat it out with a hammer if you have to form the pipe close to a bend. You can also form collectors on the press.

 

Been using this technique for quite some time now. The hydraulic press is your friend..

Look closely you can see the merge where I joined two 3" tubes into a rectangle T6 flange. The waste gates are pretty cool too, two 1.5" tube merging into a single 2.5" tube. All done using similar process to what you have shown.

 

When I worked for Hooker and was doing one offs, I would use a die similar to what you came up with (and aluminum works fine, just coat it with a bit of white grease). I had some clamps that I made that fit in the vise that would hold the tube so you could do this to bent tubing, and then smacked the die with a hammer. Sometimes, if there was a big differnce betweenthe tube size and the flange shape I would heat the tubing first.

 

OK. Not everyone's gonna have one of these...but it works. I've had to do a lot of these swedge jobs over the years, and this round material vise will hold any tube well enough.

You may need 2 swedges, one to start the form, and a larger one to get the finished shape. A single swedge may be too long to get all the way in on a curve. I weld nuts on the back of the swedge so I can put a bolt in and knock them loose. I usually hammer them in instead of using a press. Most header tubes don't lend themselves to laying on a press anyway...

(BTW, that vise works better than anything on earth when cutting or milling round stock or tubing. I've drilled mount holes in sprint car chassis on my mill with the ENTIRE side of the chassis hanging out of that vise...never even whimpered)

 

Where do you get the vice?

 

www.mscdirect.com

Item #43137462

Holds square tubing on a "diamond", and any symmetrical odd shaped objects up to 3" across.

 

This is great! Been thinkin' this for a while, I've got similar piece to fabricate... I'll just have to build my own hydraulic-press first.

 

I posed this same question to a good ol' boy I know who is great at fabrication. He said he always uses a piece of oak block, shaped with a Roloc disc to the proper contours, then drives the stub tubing down onto the wooden "die." Said it works like a charm, is fast to construct, and is durable.

-Brad

 

Glad to know the same process has worked for other people. Hope a few more of you try it. I'm excited to try it with my header. And I ill probably buy that round tube vice from McMaster.

 

What about welding the dies on porta power jaws it would stretch mostly in one direction but might work for someone who doesn't have a press.

 

Yeah this could definitely be done without a press. A BFH and a block of wood even.

I just figured presses where so affordable these days that they where accessible to most people. Harbor Freight makes one for under $200. I've got one of them at home I found on CraigsList for $50 that I use to do axle bearings, since my Blackhawk isn't all that tall. But being air over hydraulic is fantastic!

 

Nice job!!----Good pix!----Don't forget to heat up sides red hot & dimple in relief areas for bolt head clearance with socket wrench!!!---------------Don

 

Took a while for me to remember to take a picture, but I did it in steel with pretty good results.

 

Great Tech. Very well done. Thanks

 

twisted minis
go to a exhaust shop and look at a swedge box on a bender, copy the clamp and mount the die on a hyd cyl and you can go to town.. if you can find a antique first ever Huth swege box, before they made the bender, that could be modified and used to make all sorts of stuff

 

Very nice! I wanna see one with welds now.

 

Nice tech post. After you've got the tubes inserted into the flange and tacked on the flats heat the tubing in the radius area and take the proper dia rod/socket/extension, etc and tap the tubing into a nice snug fit for easier welding. I do this and weld the tubing from inside the flange. It makes a cleaner looking job not having to get a nice even weld with the uneven gap and sometimes tight fit between the center tubes that's usually present on the outside of the flange at the tubing junction. Dress the weld for good exhaust flow and your good to go.

Frank