Mine is a sidewinder and I also have the metal bobbins but you do have a notch on the side that has to be lined up with the wire before you press down firmly. I was blessed to get mine for $12 new because of a 40% off coupon. I use it often & like it, for I much rather use it that wind on my machine. It may not matter but I feel like it is better for my sewing machines. :roll: