Try several different stitch lengths on a sample square.
Make them each about 2-3 inches long and about 1/2 inch apart and mark each sample with the setting on your machine that created it.
Measure the different samples and find one closest to about 11-12 stitches to an inch. This is the one you are best using when strip piecing. It will help your seams with other kinds of piecing, too.
If you have trouble getting the tip of our seam ripper under a stitch, try using an
Clover brand seam ripper. The one below is less than $4 at
Connecting Threads -- so cheap you could order 2-3 at a time! The tip of the Clover ripper is very slender and sharp and works really well. They are one of the tools that you should replace often, as they become dull, just as you would needles or rotary blades.
http://www.connectingthreads.com/cft...paign=PPCgpGen
Jan in VA