which rotatably receives the eccentric 130 by a bearing 130a and a second portion 136 hinged to the portion 134 by a pin 137 the other end of the portion 136 is pivotally connected to a clevis 139 which receives and is fixed to a reduced diameter end portion 140 of the upper movable blade 20a during rotation of the shaft 78 the eccentrics 84 impart movement to the upper and lower blade members in directions generally perpendicular to their cutting edges simultaneously the eccentric 130 imparts a movement to the upper blade in directions along its cutting edge as will be explained in greater detail the eccentricity of the eccentric 130 is such that the blade is moved back and forth through a total distance slightly exceeding or in one instance corresponding to its edge one half tooth spacing so that precise one half tooth spacing is attained between cuts this produces the distinctive standard metal cut shown in fig1 it has been found that the phase angle relationship between the eccentrics 84 and the eccentric 130 is important this will subsequently be discussed in some detail the lower blade is similarly driven from the shaft 78 to move it in directions along its cutting edge the drive connection includes a bevel gear 150 which is connected to the lower end of the vertically.