To use remove existing sharpening guide on the Ken Onion Mk.1 and replace with 3D printed grinder attachment (Note - I have not tested part on latest Mk.2)    Select either 118 deg or 135 deg angle block to sharpen your twist drill bits.   Optional - to reduce gauging from heat buildup of the 3D printed backplate, I have added a piece of aluminum flashing to my part.