The screw grinder can be operated with the power supply used for the LessStress driling unit. If you choose another power supply, it has to have the following specifications: Input 110 - 240 V AC, Output 12 V DC, 2 A. Before using the LessStress screw grinder, please fix the nut on the screw with Loctite or something similar. Otherwise the torque can loosen the screw again. 1.) Now cut off the screw to the desired length. 2.) Now choose the desired depth for grinding by turning the metal top of the screw grinder. 3.) Turn the unit on by pressing the switch on the back. 4.) Place the screw grinder over the screw. Press your finger against the screw from the other side. This ensures a stable working position and it also enables you to feel if the screw is getting too hot. If this happens, stop the grinding for a moment to allow the screw to cool down again. 5.) Check the screw after 1 to 2 seconds to see the result of the grinding. When the screw has the desired length, you use the enclosed tool to deburr the screw.