When you cut the square 4 ways to make the triangles, you are creating a lot of bias edges. If you really want to do them that way, then you must handle and press carefully. Pick the iron up and press it down, do not 'iron' by moving the iron while in contact with the fabric as we are accustomed to doing. That's where your curves came from. Check the size of each piece as you finish it until you have a feel for the correct size. It's easier to take a minute to square everything early than try to fix it later.
Edit: When you going to work with bias like I had to with some Tradewinds blocks, starch the fabric heavily first. It can't stretch as easily with the starch.
Last edited by irishrose; 04-30-2012 at 03:00 PM.