Hole in cone layout

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Does anyone know how to layout a branch off a cone? The few layout books I've seen have pipe branches with regular diameters but not this. How to get the flat pattern of the hole in the header(a cone)? Manual Layout please, not shortcuts like putting the branch up against the cone at the right angle (30) and using a straight edge to draw the hole on the side of the cone. Cheers.
Reply:If you have 6'' pipe and you are going to have 2 1/2'' saddling into it, we would use a standard 150 pound flange ring gasket . Lay gasket on pipe in mark the inside. I'msure this would work for a cone too. Do a test with cardboard .
Reply:Multi-Hole Imager : Flange Wizard."Discovery is to see what everybody else has seen, and to think what nobody else has thought" - Albert Szent-Gyorgyi
Reply:If the branch is perpendicular to the cone surface it is almost a perfect circle given the dimensions in the pictures I attached.You can see there is little difference in the circumference effected by the penetration of a six inch pipe into the cone shape at the different heights I listed, 50 thousandths of an inch difference.If the branch off the cone is perpendicular to the axis of the cone then you would need to create a slight ellipse.  


Sincerely, William McCormickIf I wasn't so.....crazy, I wouldn't try to act normal, and you would be afraid.
Reply:Bungleu:It's not perfectly clear on what you are trying to do. Perhaps this will help? Click here.  Select the tab "Round/Tapered"  This will enable you to make a decent cut on the tube that attaches to the cone (any size round tube, at any angle, at any offset from center) but alas, it will NOT help you on cutting a hole in the cone flat pattern.  That tab was originally developed for bicycle frames with a tapered head tube, but the math is the same for your use case.  Bicycle frame guys don't cut a hole in the tapered tube, so I just left that feature out when I wrote the software.  This will give you a full size paper pattern of the mating tube.

You could use old skool drafting (on paper) with descriptive geometry techniques to develop your 'oval' shape on the cone flat pattern, per the general direction of the William McCormick posting above. An other alternative is to create a 3D CAD (three dimensional Computer Aided Design) model of your system, then unroll the cone flat pattern using a 3D CAD system like Solidworks.  What exactly are you trying to achieve?  What is the use case?  Would an exhaust style 'collector' achieve that goal better than a tube to a cone?  Is this for a commercial product, or a one off personal project?--Zip
Reply:http://www.thesheetmetalshop.com/lib...p_problems.php  (Chapters 2 and 4)http://www.thesheetmetalshop.com/pdf..._cone_ch21.pdfstart with the 2nd link.Good to just poke around in their library too.  It's all free.
Reply:

Originally Posted by Poptm

http://www.thesheetmetalshop.com/lib...p_problems.php  (Chapters 2 and 4)http://www.thesheetmetalshop.com/pdf..._cone_ch21.pdfstart with the 2nd link.Good to just poke around in their library too.  It's all free.
Reply:

Originally Posted by zipzit

That's a pretty nice resource.  Bungleu, the page you want to be looking at is page #79, figure # 96 in the pattern_book_part1a.pdf   Yup, they are definitely using descriptive geometry, but you will probably need to be using walking dividers set to a small increment to determine arc length on the cone flat pattern.  Unless you've been doing this for awhile, I'd definitely practice making simple (but highly accurate) cones first, before trying to determine the hole in the cone for the attached tube.   Take baby steps until you understand what is going on here.  Good luck with it.  --Zip.
Reply:In that last post the 0.028 is actually 0.02777777 I grabbed the rounded up version by mistake. Sincerely, William McCormickIf I wasn't so.....crazy, I wouldn't try to act normal, and you would be afraid.
Reply:Hi all thanks for all the replies very helpful. To clarify what we are trying to do I am making high pressure stainless ductwork (among other things) in a small 2 person workshop supporting an installation company here in Australia. we are chronically under resourced and overwhelmed etc. etc. but at least we get paid!Anyway I've looked up cookson and that solved the tapered branch connection issue. My next challenge is to make spot welded lobster backs out of 1.2 mm stainless with hand rollers and a tiny jenny. Cheers.