I am doing a ton of half square trianges with my Fons & Porter ruler. LOVE it by the way :)
But because I am chain piecing the ends I put in keep getting caught in the feed dogs. I do lift the foot first - and I don't even put in the side with the sharp point. I don't know what I could be doing wrong. It seems like it is almost better when I go faster but I don't have as much control that way . . any idea's?