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Need help laying out a truncated cone

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Before posting I went online looking for help...wow, was I ever in over my head.  Since this is a blacksmith project (fire pit cap) I'd see if someone on iforge could make it simple LOL    I have a plasma cutter and access to a roller but don't know where to start drawing this up.  Finished measurements are 36" diameter base, 18" rise and 10" diameter top hole. Thanks, Keith

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Good Morning,


Like Steve says use cardboard for the pattern. 36" diameter = pi x D = 113.10 inches. 10" diameter = pi x D = 31.42 inches. Add for the joint overlap. Make a mark for the center point, draw a verticle line 36" from center, swing an arc from center mark and the 36" mark, measure 56.55" on either side of the center line. That is your length of material for the 36" diameter.


Using the same center mark and center line, but at 18" down from center, draw an arc from the center mark and the 18" mark, 15.71" long on either side of center. Draw a line from the end of the 36" arc to the end of the 18" arc. Divide both lines evenly by 20 or 30 with a compass or dividers. Draw lines corresponding to each division joining each radius. This give you your bend lines.


Enjoy the math. :)



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