I'm not sure you even get 3 stitches per turn on a featherweight converted to hand crank. When I convert mine it seems like I only get one stitch per turn. The crank is directly attached, no gearing. What makes it acceptable is that I can sit outside with it in my lap and sew without needing a table to set it on.
I'd love to find a small handcrank machine that gives a reasonable number of stitches per crank.
Rob