Originally Posted by feline fanatic

Ok, you say you cut a 6 1/2 border so I am assuming this is your raw size before putting it on the quilt. I believe what you want to do is put 6 1/2 corner squares in each corner of the quilt. To make your pinwheels you need HST that measure 3 1/2 inch unfinished. When you sew these 4 units together you will end up with a 6 1/2 square. (3.5 + 3.5 = 7" -.5 lost in seam allowance = 6.5)

I usually attach my side borders first so if you also do it this way you will want to attach your 6 1/2" unfinished pinwheels to either end of you 6 1/2" unfinished top and bottom border. Attach your sides then attach your top and bottom lining up the seams that joins your border to your pinwheel with the seam that joins your quilt top and side border.