Abstract: The combination with an elongate shaft, means in operative engagement with one end of the shaft adapted to apply thrust to the shaft and another means in operative engagement with the mentioned end of the shaft for turning the shaft about its major longitudinal axis, to selectively move the shaft endwise or to rotate the same, together with a lamellate head of a thickness equal or less than a transverse dimension of the shaft, in engagement with and extending beyond the opposite end of the shaft in a plane, that, when the shaft is viewed in elevation, is substantially parallel to the major longitudinal axis and, when the shaft is viewed endwise, is at an angle to such axis; the head having a linearly extending edge and a part each in the plane of head extension, the part projecting away from the mentioned shaft axis to a point beyond the span of a shaft lateral surface and having a shoulder that extends at an angle less than a straight angle to the shaft major longitudinal axis, so that when the head is press