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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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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 |
#2
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cut pipes to weld a "T"
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/...ng/tubemit.htm Ben "Karl Townsend" wrote in message ink.net... 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 |
#3
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cut pipes to weld a "T"
"Ben" wrote in message news:Z8wpb.115238$EO3.30463@clgrps13... Look up tube mitering on google or go to these links and see the tube mitering download links ftp://ftp.ihpva.org/pub/software/index.html http://www.ihpva.org/people/tstrike/...ng/tubemit.htm I've just ****ed away 1 1/2 hours trying to get something to work here. The first link needs a postscript printer - ain't got it. The second link, tubemiter.exe prints out the paper copy of the tube miter fit to an 8 1/2 x 11 paper, not to scale. Another link on down the page, winmiter.exe has the same problem. Maybe there's something I don't know about printer setup here???? The link talking about an excel spreadsheet feeding AutoCAD would be just GREAT, but the link don't point to it. Points to some page about building bicycles. Anybody know of something else, or the old fashioned way with paper and a drafting machine? Karl |
#4
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cut pipes to weld a "T"
The real old-fashioned way, Karl, is to clamp the pipes in a T and
use a long piece of soapstone to scribe one off the other, then cut it, clean up the cut, reclamp, and scribe the other off the first, then make that cut, clean up, fit and weld. I've seen shipyard pipefitters do that hundreds of times. Grant Karl Townsend wrote: "Ben" wrote in message news:Z8wpb.115238$EO3.30463@clgrps13... 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/...ng/tubemit.htm I've just ****ed 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 |
#5
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cut pipes to weld a "T"
Does this joint need to be capable of passing liquid or air?
How much mechanical load should the joint support? It would appear that the pipe approaching the side of the other pipe requires a fishmouth cut. If no connection is required, the other pipe can be left as is. If liquid must flow, the other pipe will require a matching joint to receive the fishmouthed end. "Karl Townsend" wrote in message link.net... 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 |
#6
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cut pipes to weld a "T"
Using paper, I'd imagine a compass would be involved to draw a half circle.
Thats about all I can come up with for now. Too lazy to do much thinking at the moment. "Karl Townsend" wrote in message ink.net... 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 |
#7
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cut pipes to weld a "T"
"Karl Townsend" wrote in message ink.net... 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 I know how it's done and have to do it regularly as part of the 12 on 12 inverted branch test, which is a common welding test in the pipe field. But, it's pretty hard to describe, at least for me, your best bet is to buy one of two small books, "Blue Book of Fitters...Welders Pattern and Layout Manual" by H.G. Thorsness or "The Pipe Fitters and Pipe Welders Handbook" by Thomas W. Frankland. Both show the steps to lay out a branch as well as many other things. Or, you can buy store bought patterns, or, you can try one of the online sources mentioned tho you seem to not have had any luck there. Another alternative if you have time on your hands, is to just start whittling away until it fits. regards, JTMcC. |
#8
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cut pipes to weld a "T"
Karl Townsend wrote:
"Ben" wrote in message news:Z8wpb.115238$EO3.30463@clgrps13.. 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/...ng/tubemit.htm I've just ****ed 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 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. |
#9
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cut pipes to weld a "T"
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 Grant Erwin wrote in message ... 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 |
#10
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cut pipes to weld a "T"
I would also suggest you ask at Sci.engr.joining.welding. There are a
lot of pipe welders there. Dan "Karl Townsend" wrote in message Anyone know how this is done? Karl |
#11
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cut pipes to weld a "T"
On Mon, 03 Nov 2003 21:24:21 GMT, "Karl Townsend"
brought forth from the murky depths: Anybody know of something else, or the old fashioned way with paper and a drafting machine? 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? |
#12
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cut pipes to weld a "T"
"Karl Townsend" wrote in message ink.net... 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 Go to a welding store and buy a "Wrap Around". There are different sizes. There are instructions and marks on it that allow you to cut out the desired shape you need to get a repeatable pattern. I believe you can even order one specific to your use from them. Steve |
#13
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cut pipes to weld a "T"
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? 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 |
#14
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cut pipes to weld a "T"
"SteveB" wrote in message news:dNPpb.1834$L77.1404@fed1read03... "Karl Townsend" wrote in message ink.net... 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 Go to a welding store and buy a "Wrap Around". There are different sizes. There are instructions and marks on it that allow you to cut out the desired shape you need to get a repeatable pattern. I believe you can even order one specific to your use from them. Steve A wraparound won't give you the ordinals to cut a branch. JTMcC. |
#15
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cut pipes to weld a "T"
On Mon, 03 Nov 2003 17:05:40 GMT, "Karl Townsend"
wrote: 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 |
#16
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cut pipes to weld a "T"
Karl,
You can lay this out using a 6" red rubber ring gasket (the gasket without bolt holes) and a wrap-around or center finder attachment on your tri-square. If you happen to find one of the old asbestos ring gasket, that one works better. I'll try to describe the procedure. If I do not make this clear or understandable, I can take pictures tomorrow and send them to you. Draw a line length ways on the pipe. Using the wrap-around or center finder, find the opposite side and draw a line. Mark a line thru the center of the gasket. Now, take the gasket and lay it on the pipe with the center mark on the line and the outer ring of the gasket at the edge of the pipe. Wrap the gasket around the pipe and using soapstone, scribe around the gasket. Repeat this on the opposite side. What you'll have is two arcs drawn on the pipe. For lack of a better way to describe it, these arcs would be the "lips" of the fishmouth. Now, turn the pipe 1/4 turn from the "lips" and scribe the "corners" of the fish mouth using the gasket. Wrap the gasket around the pipe and align the outer ring with the two arcs from the "lips". Scribe this line on both sides. This is the "corners". You may have to trim some for an exact fit but this will be very close to final fit. When you're happy with the fishmouth fit, lay it on the pipe you're gonna cut into and scribe your line. Rule of thumb on this "junkyard welder" tip is to use the gasket size for the pipe size you'll be cutting into: 4" branch off 6" pipe, use 6" gasket; 4" on 4", use 4" gasket; etc.. Let me know if you need further clarification on this. Once you do it a couple of times, it'll be easy. And, fun too. On Mon, 03 Nov 2003 17:05:40 GMT, "Karl Townsend" wrote: 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 |
#17
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cut pipes to weld a "T"
JTMcC wrote:
"SteveB" wrote in message news:dNPpb.1834$L77.1404@fed1read03... "Karl Townsend" wrote in message hlink.net... 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 Go to a welding store and buy a "Wrap Around". There are different sizes. There are instructions and marks on it that allow you to cut out the desired shape you need to get a repeatable pattern. I believe you can even order one specific to your use from them. Steve A wraparound won't give you the ordinals to cut a branch. JTMcC. Just cut the main straight-through pipe so that you take out a 90 degree "bite" from one side going in as far as its centre line. Then cut the end of the branch pipe to a 90degree "V" to match the "bite" in the main pipe. Fit together, clamp and weld! ave. |
#18
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cut pipes to weld a "T"
On Mon, 03 Nov 2003 21:24:21 GMT, "Karl Townsend"
wrote: I've just ****ed away 1 1/2 hours trying to get something to work here. The first link needs a postscript printer - ain't got it. Use Ghostscript - lets you do Postscript on an ordinary printer. Geoff |
#19
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cut pipes to weld a "T"
Thanks
I'll start with this for a ruff fit, and then use the soap stone scribe idea for a final fit. Karl |
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cut pipes to weld a "T"
On 04 Nov 2003 19:02:50 GMT, (JMartin957) brought forth from the murky depths: 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? 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. 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. 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 |
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cut pipes to weld a "T"
On 06 Nov 2003 02:01:37 GMT, (JMartin957) brought
forth from the murky depths: On 04 Nov 2003 19:02:50 GMT, (JMartin957) brought forth from the murky depths: 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? 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. 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. 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. 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 -- |
#24
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cut pipes to weld a "T"
On Thu, 6 Nov 2003 14:50:44 +0000 (UTC), DejaVU
brought forth from the murky depths: Larry Jaques scribed in 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. the 'OP' wants to join 2 bits of 6 inch pipe if that makes a tool handle, I'll be jiggered Oops. I must have combined two messages. Mea culpa. (Note to Jim: Now I clearly see why you wanted to use pipefitting techniques or whatever.) -- Friends Don't Let Friends Eat Turkey and Drive -- |
#25
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cut pipes to weld a "T"
On 06 Nov 2003 02:01:37 GMT, (JMartin957) brought
forth from the murky depths: On 04 Nov 2003 19:02:50 GMT, (JMartin957) brought forth from the murky depths: 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? 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. 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. 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. 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? 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 |
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cut pipes to weld a "T"
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#27
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cut pipes to weld a "T"
On 06 Nov 2003 22:25:59 GMT, (JMartin957) brought forth from the murky depths: work. It won't even come close. Try it and see. Or, if you want, work out the math. 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? I guess you didn't try it, did you? Because if you did, you'd know exactly why it won't work. No, I didn't. 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. Um, to me, ARC and VEE sound pretty similar. I was talking about cutting the relief in the pipe. 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 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. 2. Because the paper has to wrap around the surface of the pipe, doesn't it? With a 1" pipe, yes. Not even close with a 6-incher. 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. See above 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. 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 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 |
#28
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cut pipes to weld a "T"
On Thu, 06 Nov 2003 18:28:30 GMT, Larry Jaques wrote:
On 06 Nov 2003 02:01:37 GMT, (JMartin957) brought forth from the murky depths: 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. 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? 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 |
#29
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cut pipes to weld a "T"
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#30
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cut pipes to weld a "T"
On Sat, 08 Nov 2003 02:21:57 -0500, Gary Coffman
brought forth from the murky depths: On Thu, 06 Nov 2003 18:28:30 GMT, Larry Jaques wrote: What won't work? What won't work is trying to stretch a diameter around half a circumference. In other words, the I picked up on that this morning when replying to John. Thanks. -- Friends Don't Let Friends Eat Turkey and Drive -- |
#31
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#32
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cut pipes to weld a "T"
On Sat, 08 Nov 2003 15:40:14 GMT, Larry Jaques wrote:
On Sat, 08 Nov 2003 02:21:57 -0500, Gary Coffman brought forth from the murky depths: On Thu, 06 Nov 2003 18:28:30 GMT, Larry Jaques wrote: What won't work? What won't work is trying to stretch a diameter around half a circumference. In other words, the I picked up on that this morning when replying to John. Thanks. 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 |
#33
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cut pipes to weld a "T"
On Sat, 08 Nov 2003 19:13:39 -0500, Gary Coffman
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. 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 ************************************************** **************************************** 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 !! ") _/ ) ( ) _//- \__/ |
#34
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cut pipes to weld a "T"
On Mon, 10 Nov 2003 05:14:37 +0800, Old Nick wrote:
On Sat, 08 Nov 2003 19:13:39 -0500, Gary Coffman 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. The light source would have to be at virtual infinity (sunlight would work). Otherwise you'd get geometric distortion of the shadow. Ray trace on a piece of paper and you'll see why. Gary |
#35
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cut pipes to weld a "T"
On Sun, 09 Nov 2003 19:25:10 -0500, Gary Coffman
wrote something .......and in reply I say!: *highly directional* as in spot, would, as we have all seemed to agree, be enough for non-mil-spec non-HP welds IMO. I reckon it would give as good as using a marker pen, unless you jigged the pen. But yes, the sun would be good. You would of course have to allow for the movement of the sun in the sky between drawing one side of the pipe and the other. ....... Just mumbling....Place a highly directional light directly above the work, then trace the shadow? Saves the steady hand requirement. The light source would have to be at virtual infinity (sunlight would work). Otherwise you'd get geometric distortion of the shadow. Ray trace on a piece of paper and you'll see why. Gary ************************************************** **************************************** 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 !! ") _/ ) ( ) _//- \__/ |
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cut pipes to weld a "T"
Gary Coffman wrote:
The light source would have to be at virtual infinity (sunlight would work). Otherwise you'd get geometric distortion of the shadow. While that is theoretically true, I doubt that the error induced from a light source a few feet away would matter for a welded joint. Just use a short piece of offcut from the pipe for producing the shadow. Ted |
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cut pipes to weld a "T"
On Mon, 10 Nov 2003 03:49:38 GMT, Ted Edwards
wrote: ,;Gary Coffman wrote: ,; ,; The light source would have to be at virtual infinity (sunlight would ,; work). Otherwise you'd get geometric distortion of the shadow. ,; ,;While that is theoretically true, I doubt that the error induced from a ,;light source a few feet away would matter for a welded joint. Just use ,;a short piece of offcut from the pipe for producing the shadow. I think one could use a laser pointer. Set the pointer on the inside of the perpendicular pipe and draw the outline on the other pipe. Then do the same with the laser pointer moved around the outside. The proper cut should be between these two outlines. Cheat a bit to the large size and cut. |
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cut pipes to weld a "T"
One more time. I've watched this done hundreds of times in commercial
shipyards. A new piece of soapstone is flat, and about 6" long. If you sharpen one end, and then lay the soapstone (available at any welding supply store) on the pipe so it projects over the gap onto the target pipe, then you can move the soapstone around the pipe and scribe the line of intersection. Cut this line with a torch and clean up a little with a grinder, then slide the other pipe into the cut and scribe it off the edge of the cut. Then take the other pipe back out and cut to the scribe line and clean it up with a grinder. Then fit up and weld. This process is called "scribing in" and is used in many ways in shipbuilding. You can cut the pipes in either order. The scribing only takes a few seconds. No need for a precision light source! Grant Erwin I think one could use a laser pointer. Set the pointer on the inside of the perpendicular pipe and draw the outline on the other pipe. Then do the same with the laser pointer moved around the outside. The proper cut should be between these two outlines. Cheat a bit to the large size and cut. |
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