The nozzle includes an axially extending discharge passage of circular cross-section and having a convergent entrance portion, a constricted throat which is axially and circumferentially convex, and an enlarged diameter exit portion which is concave in the axial direction as well as in the circumferential direction. The annular wall which defines the axially concave exit portion terminates perpendicular to the extreme end of the nozzle. By virtue of the shape of the passage, the plasma is discharged from the nozzle at supersonic velocity and substantially in the form of a collimated stream so as to effect faster and squarer cutting of a metal workpiece.

A storable squaring arm for use with a shear and comprising a forward section and a rear section which extend substantially parallel to the rails of the work-piece-supporting stand of the shear. The rear end of the forward section is pivotally attached to the forward end of the rear section to swing about a transversely extending axis. The rear section is pivotally attached to one of the rails to swing about a longitudinally extending axis. In order to store the squaring arm, the forward section is pivoted rearwardly about the transverse axis to a folded position on top of the rear section. The rear section is then pivoted about the longitudinal axis to a stored position below the top of the rail.

Elongated metal stock is advanced intermittently past punch presses which form holes in the stock when the stock dwells. A shear cuts off successive leading end portions of the stock and forms the stock into short pieces. The same machine is capable of running both angle iron and flat stock without making any significant conversons to the machine between runs. This is achieved through the provision of a feed mechanism and clamping units which are adapted to feed and clamp flat stock as well as angle iron.