What is the trick to lining up sashing/blocks when you don't use a cornerstone. My blocks seem to be off a little. Anyone know if there is a way to keep this from happening?

When I do sash that way, I always use a strip longer than what is needed and trim after I have sewn it on. Otherwise, I am in the same situation as you. I never cut sashing lengths until they are sewn on.

Double thread going here ... see my comment here

http://www.quiltingboard.com/t-144067-1.htm