The 1" diameter on the small end may be a problem because most slip rolls
won't go that small. Otherwise something like this should do it:

http://www.harborfreight.com/cpi/cta...temnumber=5907

You could buy a small slip roll instead of than the combination machine but
it probably wouldn't be any cheaper and I don't know if you could find one
with smaller rollers to handle the 1". Plus with the combo machine you get
a shear and that's really handy for that type of work.

Best Regards,
Keith Marshall


"The universe is full of magical things,
patiently waiting for our wits to grow sharper."
-Eden Phillpotts, A Shadow Passes, 1934
"steamer" wrote in message
...
--A friend of mine wants to build some big-ass Hero's turbines. He
wants to have the steam exiting from tapered tubes on either side of the
devices. What we need is a method to roll, or otherwise form oh, say, 18
or 20 ga. steel into tapered tubes; maybe 12" long with 1" dia on the
small end and 2 to 3" on the other end. So how is this normally done; i.e.
do we need to make a mandrel or some conic sections to drop into a custom
roll former, or what?
--TIA,

--
"Steamboat Ed" Haas : Quando Omni
Hacking the Trailing Edge! : Flunkus Moritati
http://www.nmpproducts.com/intro.htm
---Decks a-wash in a sea of words---

"steamer" wrote in message
...
--A friend of mine wants to build some big-ass Hero's turbines. He
wants to have the steam exiting from tapered tubes on either side of the
devices. What we need is a method to roll, or otherwise form oh, say, 18
or 20 ga. steel into tapered tubes; maybe 12" long with 1" dia on the
small end and 2 to 3" on the other end. So how is this normally done; i.e.
do we need to make a mandrel or some conic sections to drop into a custom
roll former, or what?
--TIA,


It's done with a slip roll (roll former). I haven't done this since high
school shop, so you may want to get some advice that's more up-to-date. g

There are two ways to do it. You can set the back roll at an angle, if your
slip roller is made for it; or you can "drag" one end of the work through
the rollers, so that the wide end is moving faster through the rolls.

In my high school shop class we had to do it both ways. I never really got
the hang of dragging the work, but I think it's a matter of practice.

Any good HVAC or sheet-metal shop should be able to do it for you, pretty
cheaply.

Ed Huntress

"Bruce Simpson" wrote in message
...
On Fri, 08 Aug 2003 17:54:45 GMT, "Ed Huntress"
wrote:

It's done with a slip roll (roll former). I haven't done this since high
school shop, so you may want to get some advice that's more up-to-date.
g

There are two ways to do it. You can set the back roll at an angle, if
your
slip roller is made for it; or you can "drag" one end of the work through
the rollers, so that the wide end is moving faster through the rolls.

In my high school shop class we had to do it both ways. I never really
got
the hang of dragging the work, but I think it's a matter of practice.

Any good HVAC or sheet-metal shop should be able to do it for you, pretty
cheaply.

The problem is going to be the 1 inch end -- the smallest regular slip
rolls I've seen have rollers about 2" in diameter.

If the rollers are too thin then they bend in the middle and
everything you roll ends up having a tighter radius at the ends than
it does in the middle.

This job might require some judicious use of hand forming to get the
small end formed. You'd be surprised what can be done with a steel
dolly (a piece of 1" diameter steel rod in this case) and a well swung
hammer :-)

--
you can contact me via http://aardvark.co.nz/contact/

Oh, yeah, that's pretty small. I've seen small slip rolls, but I don't know
if they would handle 1 inch directly.

If you can get close, you usually can pull the form around to the final
shape. 22 gage is quite thin.

Ed Huntress

On Fri, 08 Aug 2003 21:55:36 GMT, "Ed Huntress"
wrote:

Oh, yeah, that's pretty small. I've seen small slip rolls, but I don't know
if they would handle 1 inch directly.

If you can get close, you usually can pull the form around to the final
shape. 22 gage is quite thin.

Yep, hoseclamps or even some clever rope-work will likely pull the
seams into line then you can weld and bash it into something
resembling a round tube.

I use the hose clamp trick all the time to hold thin stainless tubes
before I tack along the seam. Then I clamp the bits between a couple
of chill-bars and take my TIG to the seam. The results usually work
out pretty good.

--
you can contact me via http://aardvark.co.nz/contact/

I have always wanted a 'magic' way to make small diameter tapered
tubes. Having looked the past couple of years for a simple solution,
I have kind of given up. A local blacksmith/artist acquaintance does
it by taking pipe or tubing, he then cuts a wedge shaped piece out of
the pipe, from one end to the other. Next he heats the pipe/tubing up
in his forge and the proceeds to 'close' the pipe/tube back together
using various forms he has made as an aid/support to his hammering.
Then he welds the edges back together. Once formed he the proceeds to
shape the tubing into the form of tree branches or vines. Very
laborious process, but it looks beautiful. I was thinking that a
hydraulic press might aid in the closure of the pipe, but haven't
tried it myself. Still searching for an easier way. rick

From: Trevor Jones

There are machines used to swage the
tapers into chair and table legs.

You can make ONE metal part the hard way over a form, and braze it. Make it
niiiiice inside. Then put it in a tall container and fill all round with
concrete or mortar. Then you can roll your blanks up on a regular sheet roller,
press them into the "mold" and tack inside in two places with a stick welder.

Then, if you braze, file, and polish the outside, they'll look slick.
Stainless can be matched with the righ braze filler.

Another way to do it is to have a resilient base matched to the weight of a
large flat bottomed object which presses a tapered form into the sheet. With
the right distribution of weight and "give", you can roll the taper. You'll
have to deal with sprindback, but that's super easy: just make the small end of
the form a little long...

Something like a Vlier pad (several layers of inner tube butyl rubber from the
junkyard) is cheap and adjustable. The weight can be something like an anvil.








Yours,

Doug Goncz, Replikon Research, Seven Corners, VA
Unequal distribution of apoptotic factors regulates
embryonic neuronal stem cell proliferation

wsolurb ( Doug Goncz ) wrote in message ...
From: Trevor Jones

There are machines used to swage the
tapers into chair and table legs.

You can make ONE metal part the hard way over a form, and braze it. Make it
niiiiice inside. Then put it in a tall container and fill all round with
concrete or mortar. Then you can roll your blanks up on a regular sheet roller,
press them into the "mold" and tack inside in two places with a stick welder.

Then, if you braze, file, and polish the outside, they'll look slick.
Stainless can be matched with the righ braze filler.

Another way to do it is to have a resilient base matched to the weight of a
large flat bottomed object which presses a tapered form into the sheet. With
the right distribution of weight and "give", you can roll the taper. You'll
have to deal with sprindback, but that's super easy: just make the small end of
the form a little long...

Something like a Vlier pad (several layers of inner tube butyl rubber from the
junkyard) is cheap and adjustable. The weight can be something like an anvil.








Yours,

Doug Goncz, Replikon Research, Seven Corners, VA
Unequal distribution of apoptotic factors regulates
embryonic neuronal stem cell proliferation

I saw a method when I was in Jr High school. It is called explosive
forming.
I don't have an idea of how big these tubes are but this is how I
would try it.
Machine a long bar with the taper inside of it. Mybe you might split a
solid bar first . Then thread the outside of it and put nuts on the
outside.
Then machine the tapper inside . next on the big small end make a
manderal that will fit inside of the tube your are going to taper. On
the big end of the tube make another manderal that fits on the Id of
the tube. Put silicon sealer on the manderal and the tube to make it
water tight. The tube is going to fit tight on the od on the small
tapered end and fit loose on the big taperd end. On the big tapered
end of the manderal drill the manderal to fit in a 45 cal blank shell.
then screw in a bolt about 4 times diamiter deep. Drill a hole for a
firing pin to strike the percussion cap on the 45 blank. Get a wait to
drop form a pulley and take the end of the cord and supend over the
firing pin. Get back behind somthing big and let her drop.It should
work. Make sure that the firing pin has a bigger dia than the hole so
it doesnot fire out of the bolt and act like a bullet. It might take
two or three forming attempts. If your tubes are long you might have
to take this set up out and put in blasing caps to form the tapered
tubs but that is a high vilocity blast and it might crack the tube.
give it a try and email me back how well it works.

The Hooker Super Comp ceramic coated headers did not fit the transmission
support humps in my GM A-body, so I had to make tapered offset collectors.

Making the cones was easy. Get the right size tubing for the big end and
then
carefully mark and cut out the right size triangle from the wall of the
tube, leaving
a small section attached at the big end.

Carefully work over the tube so the small ends come together. Tack weld the
small end.

Slide the cone over a mandrel -- in my case a section of 2" pipe -- and
hammer the
gap flat. Tack the center.

Smooth over any other places that might need it, then weld up the cone.

Idea
Pool cue. Find appropriate diameters on the stick. Use material 1/3
thinner than your final part. Form and or spin the metal to fit the cue.
Make a second piece. Same way but slightly larger (higher) on the cue.
Slip them together. Sweat/braze/ weld.