Abstract: A wooden workpiece is positioned on a saw table and introduced to a safety-back saw blade rotating in generally the same direction as the direction of introduction of the workpiece at the point of contact. The blade generates components of vertical and horizontal thrust of sufficient magnitude to self-feed either the workpiece or the saw, one relative to the other, at a rate compatible with the capability of the saw to cut the workpiece without generating sufficient thrust to propel the workpiece uncontrolled from the cutting and feeding operation.

Abstract: This invention is an improved electronic alarm relay for monitoring the current drawn by an AC motor or other electrical load. The circuit is designed to measure the load with high accuracy and to have excellent alarm repeatability. Chattering and arcing of the relay contacts are minimal. The operator can adjust the set point easily and can re-set both the high and the low alarm points by means of one simple adjustment. The relay includes means for generating a signal voltage proportional to the motor current. In a preferred form of the invention a first operational amplifier is provided to generate a first constant reference voltage which is higher than a preselected value of the signal voltage. A second operational amplifier is provided to generate a second constant reference voltage which is lower than the aforementioned preselected value of the signal voltage.