Abstract: A knife sharpening device having a grinding element adapted to be moved into the knife edge in a spiral path through a 180.degree. traverse and reverse, simultaneously moving longitudinally throughout the length of the knife's edge. A blade stropping element may be contained as an insert in the grinding element to strop the knife's edge during the reverse traverse.

Abstract: A sewing machine wherein the various stitch performing instrumentalities are driven by Cardan gear means. Particular sewing part mechanisms are associated with each of said Cardan gear means to produce the desired stitch. Both said sewing part mechanisms and said Cardan gear means being removable, and interchangeable within the frame of the sewing machine.

Abstract: The disclosed invention relates to an auxiliary feed mechanism adapted to maintain an edge of a workpiece in substantial registration with a predetermined path along which the workpiece edge is moved. The invention includes a motor driven auxiliary feed device which is operatively associated with a unique servosystem. The invention further includes sensing elements arranged to monitor the position of the workpiece edge and devices operatively associated with the sensing elements and the servosystem for automatically adjusting the feed rate of the auxiliary mechanism according to the characteristics of the work being sewn and for effecting the speed of the auxiliary mechanism relative to the velocity of the workpiece whereby maintaining the desired alignment of the workpiece edge relative its predetermined position or path during the sewing operation.

Abstract: Sensor including a non-contact proximity sensor, proportional change detector system and a sample gate. The machine logic program of the Automatic Sewing System generates a signal which enables the sample gate, at given times during the work cycle. The sample gate also receives a signal indicating fabric discontinuities which is generated by the sensor element. When such input signals are present, at the sample gate, an output is generated thereby to overcome the fabric discontinuities problem.