I keep my feed dogs up and the stitch length set to zero. (last 10 years) I learned this setting option for free motion from Leah Day. I have found with my stitch length set to zero, my feed dogs do not move, so my supreme slider is not damaged. Every machine is different, so make a practice quilt sandwich and try your machine both ways...feed dogs up / feed dogs down. Both options work so it's up to you to decide which option gives you the best stitch quality.