I'm going to be building a couple of 10ft dia. x 12ft high stainless holding tanks, I want to make the bottom with a slight cone so it all slopes to the center. The bottom will be made of 11ga. s.s., is there an easy way to do this?
I believe the method for developing the pattern is called radial line development. The link below may be of some help as far as how to develop the pattern. http://www.thesheetmetalshop.com
The usual slope is 12 to 1, so in this particular case, being the radius 6 feet, the slope will be 6 inches, as bhiltz says. Giovanni S. Crisi Sao Paulo - Brazil
The triangle formed by the 6" altitude of the cone and the radius of the tank 60" is solved for its hypotenuse- square root of 6^2+60^2 result 60.299 is the radius of the circle which will form the cone. But the circle is flat so we have to leave out a sector (a piece of pie shape).
The circumference of the cone making circle is Pi*(2*60.299) or 378.87 inches
The circumference of the 10 ft dia tank is pi*120 or 376.99
The difference is 1.88 inches Thus the sector to be left out is 1.88 inches at the outside tapering (in a straight line) to nothing at the center.
So to summarize- make parts that would become a circle with a radius of 60.299 (60 and 5/16 is 60.3125 probably close enough). When you cut the last piece measure back along the curve 1.88" (1and 7/8 is 1.875) so that the last piece is that much smaller than it would have been to make the circle complete. I would block up the outside so that the cone forms as it is tacked together.
Check my arithmetic I've been known to make mistakes but I have been careful.
I remain ready to explain further if this is too obscure.
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