art23 Report post Posted March 30, 2014 Hi everyone. I recently got a singer 31-20 and I still haven't finished cleaning it up. My questions are. does anyone know what's the max thread size on top and bottom? And also would needles of a singer 111w155 fit on this 31-20? The instructions manual says it gets up to a size 23 needle I kinda doubt it though. Anyone know more about this machine? Quote Share this post Link to post Share on other sites
Wizcrafts Report post Posted March 31, 2014 I used to have one of those spring foot machines. It was my second industrial sewing machine and I kept it for just two stressful weeks. If I recall correctly, it used the same needle system as the 96k40 I bought first: system DBx1, 16x257, 1738. That machine did very poorly on slick leather, with a limit of #138 thread top and bottom, using a #23 leather point needle. The stitches were all over the place, changing from long to short, as the foot slipped on the slick top grain. I think these machines would be best limited to #92 thread, which doesn't need as much thread tension as 138. The higher the thread tension, the harder it is to advance the work without compound feed. Quote Share this post Link to post Share on other sites
