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How to Drill Holes through Glass

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How to Drill Holes through Glass


Drilling a hole in sheet glass can be done if the correct type drill bit and glass is selected.

Steps


Select a sheet of glass that is suitable in size and thickness for the project you have in mind. Make sure the glass you choose is not tempered or safety glass. These types of glass can only be drilled with special equipment not available to ordinary craftsmen.


Purchase a selection of glass bits from the local home center or hardware store. These bits have a spade shaped point, and are made of tungsten carbide, to withstand the friction of drilling in glass. (Please note that multiple sites on the net recommend round-head diamond bits for holes up to 1/2", and hollow-core diamond bits above 1/2". Note that this method is a one-bit, one-pass operation).


Cut the sheet of glass the size you want for your project, or have it cut and the edges beveled or finished at the place where you buy it.

Hole too close to corner

Measure the location of your holes, being careful to stay as far away from corners and edges as possible, never drilling within 3/4 inch from any edges.

Place the glass on an extremely flat surface where it is completely supported. It is preferable to have a rubber pad or other firm, cushioning material underneath it, but the glass MUST be flat and supported.


Chuck a bit in a variable speed drill motor tightly. Starting with a small bit, maybe about 1/8 or 3/32 inch, place it at the center point of the hole location, and begin drilling. Use constant pressure pushing on the drill, and try to maintain a slow, steady drilling speed.

 
Reverse the sheet when the drill is about to reach the opposite side of the glass. Often, when the drill punches through glass, it will spall, or chip, the back side, so drilling back to meet the initial hole is better. This first hole is a "pilot" hole, it will guide the subsequent larger bits as you work your way up to the size of your finished hole.
Drill each hole required with each size bit before proceeding to the next size. As you use larger bits, less pressure should be required to keep the bit cutting, and lower drill speeds should be used.

Tips


The glass must be supported or it will break.
Do not overspeed your drill bit. Glass is very hard and abrasive, and bits can be quickly ruined.
Use a sequence of bits beginning with very small ones and working your way up gradually in size to minimize pressure on the glass.
Cutting oil may help in your drilling process, but use it sparingly.(The predominate recommendation is to cut with either a continual water spray, or more desireably, in a water bath) (a drill press would help in regulating bit pressure)

Warnings
Glass is very hard and brittle. Handle it carefully, using gloves and safety glasses.

Things You'll Need
A variable speed drill motor
Glass cutting bits
Stable, flat work surface.