One of the most critical steps in turning top quality pens is squaring the ends of your pen blanks to provide a perfect, gap free mating surface for the pen kit parts. With the Whiteside Pen Mills, this step is quick and easy. The Whiteside Pen Mill features a sharp, 3/4"-diameter carbon steel trimmer head for squaring blanks, 7mm, 10mm, 25/64", and 27/64" pilot shafts that clean excess glue from inside the brass tubes.