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oxford
10-26-2013, 08:06 PM
I have a piece of thin wall tubing that I need to expand the end on. It is actually a piece of 22ga.(.030") mild steel that was rolled and seam welded. I need to expand one end of it about .035" around .600" deep, the ID of the tube is around 1.500". I was thinking about heating the end up red and hammering a slug turned to the proper diameter in. Any other suggestions before I do the heat and beat? I have 3 of these I need to do. Thanks.

The Artful Bodger
10-26-2013, 08:12 PM
One method, make a flat tool about quarter inch thick and 1.535" wide and round the edges off. Flatten the end of the tube enough to slip this tool in the required 0.6". Now work the tool back and forth thereby stretching the metal until you can freely make a full revolution.

darryl
10-26-2013, 08:27 PM
Don't heat it- insert a solid bar about .6 inches and slowly roll it around on an anvil while hammering on the bar. You will be able to stretch the metal enough to raise the diameter that amount.

oxford
10-26-2013, 08:38 PM
One method, make a flat tool about quarter inch thick and 1.535" wide and round the edges off. Flatten the end of the tube enough to slip this tool in the required 0.6". Now work the tool back and forth thereby stretching the metal until you can freely make a full revolution.

Will this actually stretch it out, or since it is so thin just keep making the "oval" as it goes around?


Don't heat it- insert a solid bar about .6 inches and slowly roll it around on an anvil while hammering on the bar. You will be able to stretch the metal enough to raise the diameter that amount.

darryl, I don't quite under stand what you are saying. What diameter bar?

darryl
10-26-2013, 08:45 PM
The ID of the tube is about 1.5 inches- a bar say 3/4 to 1 inch diameter should work. Lay the tube on the anvil with the solid bar partway into it. You may want to support the other end of the bar so it sits level. As you hammer on the side of the bar near your tube, it will pinch the material thus stretching it. If you roll it all around you will be pinching the material all around the tube. Once around a couple of times, you should be able to see a slight bulging of the tube

oxford
10-26-2013, 08:53 PM
I am guessing the part of the tube that is getting stretched hangs off the end of the anvil?

lakeside53
10-26-2013, 08:55 PM
Buy a "Tail Pipe Expander" or similar from an autoparts or online store. Insert, wind bolt and like magic - the pipe expands...


http://www.amazon.com/s?ie=UTF8&page=1&rh=i%3Aaps%2Ck%3Atail%20pipe%20expander

oxford
10-26-2013, 09:13 PM
I have thought about the tailpipe expanders, do they work when they go in part way or do they have to be full inserted into the tube? (I know sounds bad, lol)

boaterri
10-26-2013, 09:14 PM
You could go to a local muffler shop and ask them if they would put it on their pipe machine. A Box O Joe will help ensure success.

Rick

+ or - Zero
10-26-2013, 09:14 PM
Yeah, lakeside53 has the easy solution, and inexpensive.

But I've used the method darryl described many times when it was get it done now, no expander available and to long a wait to get one. It works quite well and doesn't take all that long --thin metal like that stretches pretty easy (which is why the expanders are cheap and work).

I own a couple of the expanders, but I seem to end up at my buddies muffler shop, talking shop, while somebody uses a real machine to expand the pipe. Always seems like the easiest way to get it done --time permitting.

Zero.

Mr Fixit
10-26-2013, 10:05 PM
I have done this with Electrical Metal Tubing. I took 1" EMT and flared it by driving a machined mandrel the size I needed less the wall thickness just support the tubing and drive it in with a BFH ! It works fine. Mine was for a depth of 2" the biggest problem was getting the mandrel out without stretching the EMT more. I ended up using 1/2" EMT to drive the mandrel out.

Mr fixit for the family
Chris :)

LKeithR
10-26-2013, 10:19 PM
I have done this with Electrical Metal Tubing. I took 1" EMT and flared it by driving a machined mandrel the size I needed less the wall thickness just support the tubing and drive it in with a BFH ! It works fine. Mine was for a depth of 2" the biggest problem was getting the mandrel out without stretching the EMT more. I ended up using 1/2" EMT to drive the mandrel out.

We use this method quite often when we need to expand a tube by a small amount--usually the wall thickness. Muffler shop type expanders are hard to control to such tight tolerances. Machine your mandrel with a slight taper to get it started and then machine a straight section of the require diameter and length. No need to heat and it works great.

You can also do the reverse if you need to shrink a thin wall tube...

darryl
10-26-2013, 11:35 PM
Oxford, the part of the tube getting expanded doesn't hang off the end of the anvil, it lays right on it. Imagine if instead of a tube it was a ring, say 2 ft in diameter. You lay the OD against the anvil and pound on the inside with a hammer. If you pound on it all around, you will find it has stretched and become a larger diameter.

Another way to look at the process- say you mount a piece of solid bar in a vise with an inch or so sticking out one side. Place your tubing over that and whack it with a hammer from the OD. Rotate the tubing so you distribute the blows around the entire circumference. The end result is the same, except the solid rod held in the vise won't have the same inertial resistance that an anvil would have.

oxford
10-26-2013, 11:47 PM
Thanks darryl, I got it now.

The Artful Bodger
10-27-2013, 12:02 AM
Will this actually stretch it out, or since it is so thin just keep making the "oval" as it goes around?



Yes, the "oval" will move around but as it does so it stretches a little each time around.

DR
10-27-2013, 07:37 AM
The way I've done it is fairly simple.

Get some hard-ish rubber or urethane. Make discs, do-nuts, with the diameter matching the ID of the tube. Put a bolt through the stack of do-nuts with a metal washer on each end. Insert into tube to depth and tighten the bolts causing the discs to expand.

If the amount of expansion has to be very accurate expand the tube while it's inside of another tube with an ID equal to your desired OD.

We've used this method (with a bit more sophistication) to put threads onto tube, similar to the threads on broom handles, etc. In the metal forming industry this is known as bulging.

For very precise expansion it should be obvious seamless, DOM tube is a better starting point. The weld zone on seamed tube can affect concentricity issues of the expanded section. Be aware that all DOM is not seamless, too.

David Powell
10-27-2013, 08:33 AM
I have a piece of thin wall tubing that I need to expand the end on. It is actually a piece of 22ga.(.030") mild steel that was rolled and seam welded. I need to expand one end of it about .035" around .600" deep, the ID of the tube is around 1.500". I was thinking about heating the end up red and hammering a slug turned to the proper diameter in. Any other suggestions before I do the heat and beat? I have 3 of these I need to do. Thanks.

I made thousands of conveyor rollers with force fitted ends for a local firm. Usually the tube which was supplied had a seam. We had a reamer for each size we made to take the seam and a couple of thous of the wall thickness away. We made the plugs a few thous bigger than the reamer size and pressed both plugs in simultaneously. The small rollers were assembled using a 3 ton arbor press and an angle iron guide to prevent buckling. The big ones ( 1" dia and up) were assembled using the tee slots of my big mill as the fixture and a small hydraulic jack on its side to give the push to put the ends in. Sorry no more details, job finished ten yrs ago. Regards David Powell.

jep24601
10-27-2013, 09:01 AM
.......... Be aware that all DOM is not seamless, too.

How can DOM not be seamless?

Jaakko Fagerlund
10-27-2013, 09:52 AM
How can DOM not be seamless?
Drawn Over Mandrel is just that, DOM. It doesn't specify the starting condition at all. You can draw seamed pipe as well as seamless over a mandrel.

A.K. Boomer
10-27-2013, 10:31 AM
Talk to Andy (VPT) he has extensive knowledge in this field - just put some water in it and cap it off and toss it in the freezer...:p

(sorry Andy - could not resist)

Boostinjdm
10-27-2013, 11:41 AM
How long is the tube? The easy way would be to make a piece of shaft and press it in. Sometimes a big socket will work. Otherwise, an exhaust machine will work but you may have to expand about 2" and then trim the excess. Expanders tend to break if you only partially insert them. Been there, done that.

Mike Burdick
10-27-2013, 11:41 AM
... I was thinking about heating the end up red and hammering a slug turned to the proper diameter in. ...


Mr. Oxford probably did just that and had the job finished in a few minutes! :)

J Tiers
10-27-2013, 12:38 PM
Hammering in a slug works great....... except that the tube has to be able to stand the forces. With 0.030, you are as likely to crumple the other end, or some part of it, as to get it expanded. heating would sure help with that, but the slug will cool it down really fast.

oxford
10-27-2013, 02:37 PM
How long is the tube? The easy way would be to make a piece of shaft and press it in. Sometimes a big socket will work. Otherwise, an exhaust machine will work but you may have to expand about 2" and then trim the excess. Expanders tend to break if you only partially insert them. Been there, done that.

It is the end of a 2 stroke exhaust chamber, it is made up of a bunch segments welded together. I could cut the section off that needs to get done, it is only tack welded on but the other end it cut at an angle so it wouldn't sit flat on a press. That first segment is around 2" long. It is already to length so I can't cut any off of it.

CCWKen
10-27-2013, 02:52 PM
Go to Autozone and buy an exhaust pipe coupler/reducer for $3. One end is already expanded.

oxford
10-27-2013, 07:01 PM
I can report success on 1 of them, 2 more to go. I started using Artful Bodger's method with a 1/4" thick plate that I chucked up it the 4 jaw and turned to the diameter I needed. After a few revolutions it did start to stretch it out some but not enough so I turned another one .040" bigger than I wanted. I will say that this method does work to some extent but you will either need to make thousands of revolutions to get to the size you want or have it quite a bit bigger since the "oval" really just wants to walk around.

I then took the section of pipe off of the chamber and hammered some slugs into it to stretch it the rest of the way. It did stretch a little bigger than I would have liked so I turned a piece of pipe to the correct ID with a nice lead in taper to hammer over and shrink the OD back to the size I needed. All in all it turned out very well, if the other 2 go the same way I will be happy. Thanks for all the replies.

J Tiers
10-27-2013, 11:09 PM
Oh... my bad... for some reason I got the idea it was aluminum...... steel shouldn't (and evidently did not) crumple.

Doozer
10-28-2013, 04:19 PM
Turn some pie jaws for the 3 jaw chuck.
Insert your tube. Open the chuck.

--Doozer