Radius Turning Tool cuts a ball-shaped end or turns a radius on the end of a workpiece. It's simple to use: mount the 3/8 inch square shank of the outer frame in your lathe's tool post. Then, swing the handle to rotate the cutting tool bit in a smooth arc. Use for making universal couplings, decorative ball-ends on handles, and much, much more. Cuts ball-shapes up to 3/4 inch diameter. Includes high speed steel tool bit. Made of sturdy, corrosion-resistant blackened steel.