A power tool assembly comprising: a drop arm assembly movable along a drop path between a first drop arm assembly position whereat a portion of a shaping device supported by the drop arm assembly extends above a workpiece support surface and a second drop arm assembly position whereat the portion of the shaping device does not extend above the workpiece support surface , the drop arm assembly including a drop arm frame with an opening configured to rotatably support an arbor shaft , a lower surface spaced apart from the opening , and a plurality of ribs extending between the lower surface and the opening , wherein the plurality of ribs define a respective one of a plurality of axes, the plurality of axes intersect at a locus , and the locus is adjacent to, but spaced apart from, a center of gravity of the drop arm assembly ; an actuating device configured to transfer a force to the drop arm assembly when the drop arm assembly is at the first drop arm assembly position; and a control system configured to control the actuating device to transfer the force to the drop arm assembly when an unsafe condition is sensed, characterized in that the drop arm assembly moves within a drop plane as it moves along the drop path; the center of gravity is at least in proximity to the drop plane ; the drop arm frame includes semi-spherical strike pin located in the strike plane, and wherein a pyrotechnic housing is configured to center the active shot substantially on the drop plane . a drop arm assembly movable along a drop path between a first drop arm assembly position whereat a portion of a shaping device supported by the drop arm assembly extends above a workpiece support surface and a second drop arm assembly position whereat the portion of the shaping device does not extend above the workpiece support surface , the drop arm assembly including a drop arm frame with an opening configured to rotatably support an arbor shaft , a lower surface spaced apart from the opening , and a plurality of ribs extending between the lower surface and the opening , wherein the plurality of ribs define a respective one of a plurality of axes, the plurality of axes intersect at a locus , and the locus is adjacent to, but spaced apart from, a center of gravity of the drop arm assembly ; an opening configured to rotatably support an arbor shaft , a lower surface spaced apart from the opening , and a plurality of ribs extending between the lower surface and the opening , wherein the plurality of ribs define a respective one of a plurality of axes, the plurality of axes intersect at a locus , and the locus is adjacent to, but spaced apart from, a center of gravity of the drop arm assembly ; an actuating device configured to transfer a force to the drop arm assembly when the drop arm assembly is at the first drop arm assembly position; and a control system configured to control the actuating device to transfer the force to the drop arm assembly when an unsafe condition is sensed, characterized in that the drop arm assembly moves within a drop plane as it moves along the drop path; the center of gravity is at least in proximity to the drop plane ; the drop arm frame includes semi-spherical strike pin located in the strike plane, and wherein a pyrotechnic housing is configured to center the active shot substantially on the drop plane . <EOS>