A process for cutting a sheet glass includes a first step of forming a groove conformed to a cutting shape in one surface of a sheet glass by a water jet, and a second step of forming a groove in the other surface of the sheet glass by a water jet to reach the groove, which are carried out sequentially, thereby cutting the sheet glass. The edge of each cutting instrument is oriented away from a resting surface so as to reduce or avoid the dulling of the edge. At least one power converter coupled to the first terminal and the second terminal and configured to convert power from the power source from a first voltage level to a second voltage level and to provide power at the second voltage level to the switch controller. A mounting fixture is provided enabling the grading attachment to be removably attached to a motorized vehicle. A second feedback resistor is coupled between the output of the output amplification stage and the input of the transconductance stage. Thus, the interrogation zone covered by the antenna’s magnetic field is continually changing with the movement of the door.