Drill in the home hole with a diameter of 20-and 80-millimeters and is quite problematic. Drills this diameter in the home is not found, and punch a hole, even in tin and sheet metal with a chisel or a drill bit is not obtained if you want to save the plane. You can certainly drill a hole with a diameter of up to 3 mm around the circumference of the distance between the axes 4 – 5 mm.

And then cut the remaining septum chisel, knife, or the same drill, turning on an electric drill 40 – 60 degrees to either side at a tangent to the circle. But with a small thickness of the sheet even during openings plane can be broken, and at a thickness of up to 2 mm will break more than one drill, and all equal to the hole the correct form, if needed, can not be achieved. Under the conditions of home metal workshop can solve this problem differently. To manufacture the nozzle at a drill that will cut perfect holes in sheet metal, pcb, plastic or Plexiglas. First of all, you need to find a metal trash present in the studio, a massive metal disk, such as gear from the worm gear. If it is a fixed axis, it will remove some problems, most importantly, the diameter of the axle (rod), measured using the gauge was not greater than the possibility of an electric drill chuck. In the drive to drill a hole with a diameter ranging from 4 to 7 mm at a distance from the center of the disk, equal to roughly the radius of the hole that needs to be drilled in the sheet material.