cut pipes to weld a "T"

I need a "T" made out of two six inch 1/8" wall thickness pipes.
I need a way to mark a chalk line on each pipe so I can cut it with a torch
and then fit the two together and weld.
I did a layout like this in drafting class thirty years ago. Made each piece out of paper. Cut them out and wrapped around the pipe to mark the lines. I don't remember much else about it.
Anyone know how this is done?
Karl
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Look up tube mitering on google or go to these links and see the tube mitering download links ftp://ftp.ihpva.org/pub/software/index.html http://www.ihpva.org/people/tstrike/building/tubemit.htm
Ben

torch
piece
I
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I've just pissed away 1 1/2 hours trying to get something to work here. The first link needs a postscript printer - ain't got it.
The second link, tubemiter.exe prints out the paper copy of the tube miter fit to an 8 1/2 x 11 paper, not to scale.
Another link on down the page, winmiter.exe has the same problem. Maybe there's something I don't know about printer setup here????
The link talking about an excel spreadsheet feeding AutoCAD would be just GREAT, but the link don't point to it. Points to some page about building bicycles.
Anybody know of something else, or the old fashioned way with paper and a drafting machine?
Karl
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The real old-fashioned way, Karl, is to clamp the pipes in a T and use a long piece of soapstone to scribe one off the other, then cut it, clean up the cut, reclamp, and scribe the other off the first, then make that cut, clean up, fit and weld. I've seen shipyard pipefitters do that hundreds of times.
Grant
Karl Townsend wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Another old fashioned way is to use something fairly stiff as some heavy gasket material to hold on the pipe in what you think is the right shape and mark it with soapstone. Cut with oxy/acet, see how much you missed it by and mark again using the guide. A piece of four or six inch wide flat belt a couple of feet long would work real well.
With six inch dia pipe, the deepest part ought to be 3 inches in from a straight cut end.
Dan

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Karl Townsend wrote:

I just ran your dimensions on Tubemiter. The units are mm, so you have to convert from inches to mm. The printout was only 1/2 the template, so you need to run it twice and paste them together. I didn't try it, but it looks about right.
I also ran your dimensions on Winmiter. Again, the printout was only 1/2 (in landscape mode) the template. But print and paste two copies and you have a whole template.
I did overlay the printouts from both programs, and they match very closely.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 03 Nov 2003 21:24:21 GMT, "Karl Townsend"

Hold the end of one pipe on a piece of paper (or use a coin the same size if possible, and draw a circle. Fold the paper in half so the arcs line up and cut out the circle. Wrap that around the pipe, mark, cut, and grind to suit. Flop the cut piece over and weld it. Easy enough?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Easy enough, but it won't work.
Your way, you'll get an arc (a half-circle, actually) with a chord length equal to the pipe diameter, and with the arcs tangent at 90 degrees to the chord.
The correct pattern will be an arc with a chord length of pi divided by twice the diameter, and with the arcs tangent at 45 degrees.
Instead, I'd make the 45 degree cuts on the end of the vertical piece first, and make a pattern from that. Or, butt the pieces together and scribe the joint.
John Martin
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 04 Nov 2003 19:02:50 GMT, snipped-for-privacy@aol.com (JMartin957) brought forth from the murky depths:

Wasn't the OP asking for a tool handle? Did he ask for mil-spec welding info? "Why seek perfection for a bloody pipe/handle?" I ask in earnest.
P.S: I grant that your method would be much prettier.
-- Friends Don't Let Friends Eat Turkey and Drive --
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Larry:
It's not a question of perfection. What you suggested he do just plain won't work. It won't even come close. Try it and see. Or, if you want, work out the math.
John Martin
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 06 Nov 2003 02:01:37 GMT, snipped-for-privacy@aol.com (JMartin957) brought forth from the murky depths:

Take 1" (example) pipe, cut in half. Hold end to paper, draw 1" circle. Fold paper in half at circle. Cut out 1" x 1/2" semicircular arc. Fold paper around end of one pipe. Draw arc. Rotate pipe 180 degrees, draw arc. Cut out arcs. Grind to fit pipe. (requires no math ;) Weld together.
What won't work?
-- Friends Don't Let Friends Eat Turkey and Drive --
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I guess you didn't try it, did you? Because if you did, you'd know exactly why it won't work.
You are talking about using the pattern to cut the point on the end of a piece of pipe, rather than a vee in the middle, but no matter because it's the same thing.
Given your example, the two ends of the arc on your pattern are exactly 1" apart. On the piece of pipe you want to cut, the two points or the bottoms of the vees will be 1" apart, as that is the diameter of the pipe. But, when you wrap your pattern around the pipe, the ends of the arcs won't make it halfway around the pipe - because halfway around the pipe is really 1.57", or pi over 2. Because the paper has to wrap around the surface of the pipe, doesn't it?
And not only will your pattern not stretch halfway around the pipe, as it should, but when you trace it you'll find that the ends of your arcs meet the square end of the pipe at an angle (tangent) of 90 degrees. Not at 45 degrees as they should.
The poster who suggested using a rubber ring as a pattern will get the same cut you do, although with the flex and stretch of the ring he'll get closer.
John Martin
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 06 Nov 2003 22:25:59 GMT, snipped-for-privacy@aol.com (JMartin957) brought forth from the murky depths:

No, I didn't.

Um, to me, ARC and VEE sound pretty similar. I was talking about cutting the relief in the pipe.

OK, you got me with the actual size, but I said to hold the end of the pipe to the paper and draw the circle.

With a 1" pipe, yes. Not even close with a 6-incher.

See above re: stretchmarks. As to the angle, why would a cut which was radiused to the OD of the pipe -not- fit? The ends of the arc would be to the outside of the pipe, not the inside, so there would be no 90 step. I'll give you the fact that I didn't address the proper fit for a certified weld, but I'm a certifiable jury rigger. So sue me. ;)
-- Friends Don't Let Friends Eat Turkey and Drive --
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Larry:
I've seen other posts from you here, and you seem like a decent guy. I really haven't had any intention to insult or demean you.
What you wrote here, however, was simply wrong. I tried to point out to you in a couple of ways exactly why it was wrong. I suggested at least twice that you actually try what you had recommended. Nothing more complicated than tracing the end of a pipe (or even a can) on a piece of paper, cutting along the line, and wrapping it around the pipe to see the pattern. You couldn't be bothered.
I tried going through your latest reply, but it's just gibberish. "See above re: stretchmarks." What above, what stretchmarks? "a cut which was radiused to the OD of the pipe". Whatever that means. "The ends of the arc would be to the outside of the pipe, not the inside, so there would be no 90 step." Simply can't follow you there, either.
Obtaining the proper fit for a certified weld has nothing to do with this, as the method you proposed won't even come close. But, since ou couldn't be bothered to even try it, I guess you'll never know.
Over, and out.
John Martin
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 08 Nov 2003 05:11:34 GMT, snipped-for-privacy@aol.com (JMartin957) brought forth from the murky depths:

Ah, the light dawns. I just tried to visualize doing that and see exactly what you meant. When wrapping the paper around the pipe it gets narrower (from a 2-D standpoint) due to the wrap. I was thinking in 2-D and trying to work in 3-D.
You're absolutely right. I sit corrected. (too lazy to stand.)

I was thinking 1" pipe when the OP had 6" in mind. The paper would have stretchmarks trying to fit the 6. (Eez joke, mon.)

Ditto. And thanks for following through and helping me to see my error.
-- Friends Don't Let Friends Eat Turkey and Drive --
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 06 Nov 2003 22:25:59 GMT, snipped-for-privacy@aol.com (JMartin957) wrote:

And I assume that you didn't try the ring gasket wrap method because if you did, you would have seen that it does indeed work! I do it all the time. Don't need no formulas or pi or calculators. Turn off your calculator, get off your ass and go out in your shop and try it.
Geez, the guy asked for help laying out a piece of pipe not a lesson in math. Hell, if we all understood how to mathmatically design a template for this stuff we wouldn't ask for help.
Instead of telling everybody else how wrong they are and why according to your calculator, their idea stinks, why don't you whip up a template for the guy so he can get his pipe cut because all the rest of us don't know what we're talking about.
I'm gonna go cut some pipe.
James
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

What won't work is trying to stretch a diameter around half a circumference. In other words, the part you need to mark and cut is 1.57 times longer than the template you're wrapping around it.
Now if you were to leave your template *flat*, and project lines down from it to the circumference of the pipe you want to mark, it will describe the correct curve you need to cut in the pipe.
Gary
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
brought forth from the murky depths:

I picked up on that this morning when replying to John. Thanks.
-- Friends Don't Let Friends Eat Turkey and Drive --
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

You're welcome. It should be obvious that what you really have to do to project a 2D figure onto a 3D surface. What may not be so obvious is that wrapping the 2D figure around it won't do that, because the projected figure on the pipe surface is an ellipse, not a circle.
The easiest way to generate the correct figure is to hold the 2D template *flat* above the pipe, and drop perpendiculars down to the pipe surface to form the required curve. (A stiff template and a long marking pen will do for the precision needed for welded joints.)
BTW, the flat projection method will also correctly describe the elliptical mating hole you need to cut in the other pipe.
Gary
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote something ......and in reply I say!:
Just mumbling....Place a highly directional light directly above the work, then trace the shadow? Saves the steady hand requirement.

****************************************************************************************** Until I do the other one,this one means nothing Nick White --- HEAD:Hertz Music
remove ns from my header address to reply via email
!! <") _/ ) ( ) _//- \__/
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.