dude Posted February 26, 2011 Author Share Posted February 26, 2011 Any chance you can flatten one side out and tell me if it is a proper ellipse? I have a hunch it is but I need proof to make sure I am doing my calculus correctly. Quote Link to comment Share on other sites More sharing options...
paulmcz Posted February 26, 2011 Share Posted February 26, 2011 You don't need to go 3D to find out that the figure is NOT an ellipse. See how the hole cutout shape changes as you enlarge its size. HoleCutout.dwg Quote Link to comment Share on other sites More sharing options...
dude Posted February 28, 2011 Author Share Posted February 28, 2011 Thank you. Tell me something, how did you know how to model those lines without going 3D. There are two planes to look at here, the 48" inside diameter or the outer 58" outside diameter. I am looking at the cut through the inside 48" diameter. I am getting the height of cored hole (24" dia. cored hole) is 24" tall and 25.1327" wide when flat (or measured around the arc circumference. Your drawing does not reflect this the best I can tell. Any thoughts on this? Quote Link to comment Share on other sites More sharing options...
paulmcz Posted February 28, 2011 Share Posted February 28, 2011 Thank you. Tell me something, how did you know how to model those lines without going 3D. There are two planes to look at here, the 48" inside diameter or the outer 58" outside diameter. I am looking at the cut through the inside 48" diameter. I am getting the height of cored hole (24" dia. cored hole) is 24" tall and 25.1327" wide when flat (or measured around the arc circumference. Your drawing does not reflect this the best I can tell. Any thoughts on this? Long before you and I were born, there were no computers and no 3D software and despite that, people were still able to calculate and draw these basic figures. I was thinking that if they could do it, I should be able to do the same with the stuff I learned from them in geometry classes, last century. It seems to me that since we have 3D software, they don't teach those methods anymore. Or do they? Look at the thread (link bellow) to see a step-by-step procedure of a similar (but bit more complex) case. Since in my reply I answered only your 'ellipse' question it doesn't really matter if the geometry on my drawing is figured out for Ø48 cylinder or Ø58 cylinder. I simply chose outer surface of your tube (Ø58) and that's why I have different dimensions than you. Your "25.1327" is correct for calculations with the Ø48" cylinder. Either way, the answer to your original question still remains that the figure is NOT a perfect ellipse. http://www.cadtutor.net/forum/showthread.php?56374-Pipe-templates Quote Link to comment Share on other sites More sharing options...
dude Posted March 1, 2011 Author Share Posted March 1, 2011 (edited) You are correct. It is not a proper or perfect ellipse. In fact, the math says it is larger than an ellipse. I will look at that tutorial tomorrow. Thank you again. I am from the time period before 3D drafting. ;-) My high school math teacher did not know calculators could do sin, cos, etc. My triple integral uses a projection to get as perfect wall volumes humanly possible but I am trying to narrow this down to a simple equation for people to implement easily. I thought the shapes would be ellipses. I was wrong. You can see this is taking a long time to get to the bottom of. I'll check back in! Edited March 2, 2011 by dude Quote Link to comment Share on other sites More sharing options...
dude Posted March 1, 2011 Author Share Posted March 1, 2011 One last thing, checking numbers helps me confirm I am on the straight and narrow. Thanks for acknowledging my correct numerical answer. I really appreciate everyones help on this. Quote Link to comment Share on other sites More sharing options...
Jack_O'neill Posted March 1, 2011 Share Posted March 1, 2011 Dude, Just out of curiosity, you wouldn't by chance be trying to "clip" a round hole in a piece of tubing would you? Quote Link to comment Share on other sites More sharing options...
dude Posted March 2, 2011 Author Share Posted March 2, 2011 I am not sure I follow you. I am trying to determine the shape's volume. First I verified with calculus as an "exact" (or very very very very close approximation for those math buffs) and now want to create a formula easier for programmers and normal people to use with a normal calculator. We are actually coring a hole through a hollow cylinder with a wall thickness of 5". Everything may vary in size but we will always being forming or coring a hole through a hollow cylinder. Mapping this out in 2D to see the actual shape is on the block for evaluation. I am going to do an example with an oatmeal box tomorrow and see what real life says. Does this help Jack? Quote Link to comment Share on other sites More sharing options...
Jack_O'neill Posted March 2, 2011 Share Posted March 2, 2011 I am not sure I follow you. I am trying to determine the shape's volume. First I verified with calculus as an "exact" (or very very very very close approximation for those math buffs) and now want to create a formula easier for programmers and normal people to use with a normal calculator. We are actually coring a hole through a hollow cylinder with a wall thickness of 5". Everything may vary in size but we will always being forming or coring a hole through a hollow cylinder. Mapping this out in 2D to see the actual shape is on the block for evaluation. I am going to do an example with an oatmeal box tomorrow and see what real life says. Does this help Jack? I hadn't read all of the previous posts when I asked the question, but it looked and sounded very similar to a project I did at a previous employer many years ago. We weren't working with anything as big as you are, but were essentially doing the same thing. The product in my case was 4" diameter copper tubing, and we were making manifolds for industrial sized air conditioning units. "Clipping" was our term for using a punch and die on a punch press, with a mandrel inside the tube to act as a shear surface to slice out a hole in the side of the tube. Like you, we were concerned with the flow rate through that hole, but in some cases we were trying to insert a somewhat smaller tube in that hole and braze/weld it in place. We had calculated an elliptical shape that we thought would give us the "round" hole we wanted, but discovered that what should have worked didn't quite produce the results we wanted. Much trial and error followed, and while we finally got a round-ish hole, it was never quite good enough for the customer that wanted it. With the machining equipment availabe at the time, these changes to the tooling were costly and time consuming. We eventually scrapped the whole idea and developed an attachment method that actually involved flaring the feeder tube in a saddle shape and brazing that over the outside of the larger tube. I was just curious, this thread brought back memories of some long but interesting days gone by. Quote Link to comment Share on other sites More sharing options...
dude Posted March 2, 2011 Author Share Posted March 2, 2011 I see. You were attempting almost an identical task. We can produce a perfect round hole but can't flatten out concrete to see the actual shape made in 2D. Thanks for sharing. I love hearing stories like this. Quote Link to comment Share on other sites More sharing options...
Jack_O'neill Posted March 2, 2011 Share Posted March 2, 2011 I see. You were attempting almost an identical task. We can produce a perfect round hole but can't flatten out concrete to see the actual shape made in 2D. Thanks for sharing. I love hearing stories like this. We could get a round hole by drilling it, or in the case of the smaller tubes we'd simply punch the hole. The large feeder tube hole was almost the same size as the ID of the tube, so a conventional punching operation over the centerline of the tube was impossible. Slicing it off center was our only option. Drilling had too long a cycle time, and the interupted cut made for a ragged edge that had to be deburred. Of course, none of this helps you with concrete. What a mess a punch press would make of that! Quote Link to comment Share on other sites More sharing options...
paulmcz Posted March 2, 2011 Share Posted March 2, 2011 I see. You were attempting almost an identical task. We can produce a perfect round hole but can't flatten out concrete to see the actual shape made in 2D. Thanks for sharing. I love hearing stories like this. If you need flat shape of the cutout Ø24 and Ø42 for inner and outer surfaces of the Ø48ID x Ø58OD cylinder, see the attached drawing. SRFC.dwg Quote Link to comment Share on other sites More sharing options...
dude Posted March 3, 2011 Author Share Posted March 3, 2011 Testing because the message above is causing an error and I can't view it. This fixed the problem. Quote Link to comment Share on other sites More sharing options...
mathew21 Posted March 4, 2011 Share Posted March 4, 2011 would it be possiable for you to make it out of a materal you could flatten out? that way you could get the measeurements you want? or ive got a thing i call the little black book.. its a the pipe fitters and pipe wealders handbook.. it seems to have something very similar to what you may be looking for they give a discription pictures and how to do it but no formula other than the instrructions.. Quote Link to comment Share on other sites More sharing options...
mathew21 Posted March 4, 2011 Share Posted March 4, 2011 ok can anyone else not look at page 4 of this? keeps givin me a error Quote Link to comment Share on other sites More sharing options...
dude Posted March 4, 2011 Author Share Posted March 4, 2011 (edited) This thread gives an error for me too. PaulMCZ, how did you model that shape in AutoCAD? Are you still using the same method as you described in the previous post? mathew21, since it is not a perfect ellipse and my goal is to model these exactly without Calculus, this problem becomes difficult. I want to predict these volumes over a vast range of diameters and hole sizes. Edited March 4, 2011 by dude Quote Link to comment Share on other sites More sharing options...
paulmcz Posted March 4, 2011 Share Posted March 4, 2011 ... how did you model that shape in AutoCAD? Are you still using the same method as you described in the previous post? Actually, I wrote a lisp program based on the method very similar (the same idea) to the one shown in the other link, so I don't have to draw it manually. The program deals with a cutout (wrap-around) templates for all kinds of two or more pipe joint configurations and draws the shapes based on data entered on the command line. The program was sold and for that reason is not available to the public at this time. It will be soon though as the company is about to close all their business operations. BTW, the lisp routines don't work in AutoCAD LT. Quote Link to comment Share on other sites More sharing options...
paulmcz Posted March 4, 2011 Share Posted March 4, 2011 I just tested the idea of getting the flat shape of the Ø24 hole out of cylinder Ø53 instead of Ø48 or Ø58 and multiplying by wall thickness of 5. The volume figure came very close to the exact outcome of the volume of 3D AutoCAD model. AutoCAD showed the volume of 2325.6666, where my test came out as 2324.8105. I know that it is not exactly kosher but it could be close enough if you want to avoid calculus. Quote Link to comment Share on other sites More sharing options...
Jack_O'neill Posted March 4, 2011 Share Posted March 4, 2011 ok can anyone else not look at page 4 of this? keeps givin me a error The hackers were playing again yesterday. I couldn't get in to the site past the title screen all day. David has fixed the problem, at least till they find a way in again. Quote Link to comment Share on other sites More sharing options...
mathew21 Posted March 5, 2011 Share Posted March 5, 2011 ahh if u just need the volume then the book will not work.. but if u just need to cut the hole it will.. the way they lay it out doesnt take anythhing expect simple math Quote Link to comment Share on other sites More sharing options...
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