Log cabin blocks were a nightmare for me, until this tip. Cut all your strips to size, stitch, finger press only adding strips as you go. When block is done iron on back of block only. I made 80 for my daughters quilt. Three were off a bit. I blocked them to size this way. Damped with spray of water. pinned to correct size on padded mat, let dry. Worked great and I did not have to trim. Hope this helps.