This board shows how to use a rack-type cutter to cut involutes from gear teeth. It comprises of three white acrylic discs, A, B, and C, with corresponding pitch circle diameters of 450, 300, and 200 mm. On a piece of paper positioned between the disc and the cutter, a gear tooth profile with a 25mm module can be sketched out. The profiles drawn can be used to study how interference and undercutting effect the proper gear tooth profile.