
All this is achieved with a metal tube of appropriate diameter and powder abrasive. Else you can use a simple jig — a piece of plywood with a hole the diameter of the tube.
The scheme of drilling pipe:
1 — metallic (copper) tube, 2, 3 — plywood jig, 4 — emery powder, 5 — drilled glass, 6 — cardboard lining.
The whole operation takes about fifteen minutes depending on the thickness of the glass. On a flat surface put a piece of cardboard, a glass, and the top is plywood jig. His hole entered a few drops of water and a thin layer of emery powder. Then insert the tube and rotate it left and right. After a few turns of the glass surface is clearly labeled with the annular groove.
With the deepening of the tube and approaching the drilling process by the end of the pressure should gradually ease, to avoid chips and cracks on the lower side of the glass.
I. EDELMAN