Originally Posted by cat-on-a-mac

I hope you meant 12 1/2"? Yes, I came to the same conclusion. I decided to square up to 8 3/4. Then use 7 1/2 inch blocks to do the outer triangles. That's generous, with quite a bit to trim off, but I'd rather have that than be too small. BUT, I end up with more than 1/4 inch beyond the points of the last square-in-square ... I guess that's not critical?