thank you! thank you! that answers my question. I didn't know where to start.

There are some great charts and tips at Quiltville. Here are a couple related to on point settings:

http://quiltville.com/onpointmath.shtml

http://quiltville.blogspot.com/2010/...ing-chart.html

A 10" square block is going to measure ~14" across when on point (across the diagonal).

(the formula is 1.41 x the size of a side of the square - something to do with pi but I doubt you want the details).

So, for a queen size quilt - let's say you want something around 90" x 110" (that's 15" drop on both sides) -
you'll need 6 blocks across 7 blocks down.

That would be total of 72 blocks, plus setting triangles, plus border to get to your final measurments.

Without a border, that would measure 86x100.