A pair of holding arms which can be installed quickly and used to press a workpiece in a safe manner against a guide fence, regardless of the cuts made upon it, when the workpiece is moved past a shaper having cutter blades rotatably mounted on a stationary shaft. The moveable structure for selectively narrowing the width of the arch wire slot may be defined by one or more spaced apart cuts disposed in at least one side wall defining the arch wire slot so as to define a bendable portion of the sidewall. Lastly, there is a mechanism provided which engages the step like member adjacent a front portion thereof and a pre-selected member disposed in such engine compartment for providing a second portion of support for the step like member.