Sewing machine, bobbin and bobbin case therefor and use

摘要

A sewing machine which may employ a loop-making hook rotating about a vertical axis employs a one-way bobbin and bobbin case. A bobbin can have a larger flange and a smaller flange so as to fit in a suitably configured bobbin case in only one way. The bobbin may have a blind axial opening with a guide groove to fit a winder spindle in only one way so that the bobbin can only be wound in one way. Attempts at incorrect orientations cause the bobbin to protrude from the bobbin case in an obviously incorrect manner. Inadvertent efforts to wind the bobbin incorrectly are likely to be fruitless. Thus, a user can readily install the bobbin in the bobbin case with a proper orientation and with the thread correctly wound. Surprisingly, stitching problems, such as poor seams or the like, can be reduced.