Re: Round foundation help
Tony
Try this:
http://www.cleavebooks.co.uk/scol/callipse.htm
So for your 21x18 (axis 42x36), the foci = 21.6.
Measure over to the middle, 21 inches, then put a nail in at 21.6/2= 10 3/4 inches each side on the base line. These are the ellipse foci.
Put a nail in at one end of the 42 inch line. To get the loop length, tie a cord loop tight around this this nail and the farthest of the two foci nails. Now, take the cord loop and loop it around the two foci nails. Now put a pencil inside the loop and draw the ellipse.
Note that the height you have chosen, 18 inches, is 85% of the radius. This is at the most aggressive end of the 85-90% "rule of thumb" ratio. At 90%, the height would be 21x.9= 18 7/8. I would go for about 18 1/2 inches. Take a look once you have drawn it.
Note also that because your soldiers are 4 1/2 inch vertical, you have to "catch up" to the ellipse over the first 2-3 courses, see below (this sketch is for a smaller ellipse - on a larger one it is easier to "catch up").
Tony
Try this:
http://www.cleavebooks.co.uk/scol/callipse.htm
So for your 21x18 (axis 42x36), the foci = 21.6.
Measure over to the middle, 21 inches, then put a nail in at 21.6/2= 10 3/4 inches each side on the base line. These are the ellipse foci.
Put a nail in at one end of the 42 inch line. To get the loop length, tie a cord loop tight around this this nail and the farthest of the two foci nails. Now, take the cord loop and loop it around the two foci nails. Now put a pencil inside the loop and draw the ellipse.
Note that the height you have chosen, 18 inches, is 85% of the radius. This is at the most aggressive end of the 85-90% "rule of thumb" ratio. At 90%, the height would be 21x.9= 18 7/8. I would go for about 18 1/2 inches. Take a look once you have drawn it.
Note also that because your soldiers are 4 1/2 inch vertical, you have to "catch up" to the ellipse over the first 2-3 courses, see below (this sketch is for a smaller ellipse - on a larger one it is easier to "catch up").
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