Abstract: A sewing machine bobbin adapted for disposal in a bobbin case. The bobbin includes a hollow cylindrical core on which a thread mass is wound adapted for slidable disposal over a center post mounted in the bobbin case, and a latch is mounted on the post for securing the cylindrical core and the thread mass in the bobbin case, the post and the latch having a combined axial length greater than the axial width of the bobbin case. The improvement of the invention comprises constructing the hollow cylindrical core so that the edge of at least one end thereof is axially tapered radially inwardly along the axis of the core away from its end towards the center post of the bobbin case and has an axial length which is greater than the axial distance between the bobbin case and the latch. The thread mass is wound on the core so that the tapered edge extends axially outwardly along the core axis beyond the surface of the thread mass.