The Handyman's Pocket Book: Boring Through Glass.

Glass is a difficult material to bore.  This method is necessarily slow and somewhat hazardous and should therefore be attempted only on glass which is of secondary importance.

The boring tool is made from a discarded 5-in. triangular saw file.  It has three equal sides and these curve towards the tip.  On a grinding wheel grind the tip of the file to the shape shown below.  Square the end until each edge measures about 0.3 in. (A), keeping the surface square to the file axis.  Grind each edge of this triangular tip to about 25 degrees, as at B, using the flat side of the wheel and holding the file level.  The scratches on each triangular face will thus be at right angles to the file axis.  This ensures that the three sloping corners on the tip, which do the actual grinding of the hole, are of the correct serrated nature.  Grind each corner off to about 1.25 in. from the end as at C.  Undercut slightly so that the tip has the biggest section of this 1.25 in. length.  Dip the file frequently into cold water so that it does not get hot.  This is most important.

The other end of the file fits into the chuck of an ordinary brace.  Make sure that the glass rests on a perfectly flat surface.  It take about 30 minutes to bore through 0.2 in. glass.  The lubricant used is turpentine, and a tin of this should be kept handy, the tip being immersed in it every few minutes.  The brace may be turned steadily either way with firm pressure until nearly through.  It is at this stage that the danger of breakage is greatest.

To minimize the danger have a sharpe centre punch handy and tap the middle of the hole with it.  If only a thin film of glass remains at this stage the tip of the centre punch will pierce it easily and the boring tool will soon remove the rest.  The thing to guard against is a sudden break through.