How to Cut Glass

Cutting glass is a job well within the capabilities of the DIY/home enthusiast so long as you follow these basic tips as to how to cut glass properly. The first thing to realize is that there are limits as to what size of glass pane you can realistically cut. Cutting clear glass that is 3mm in depth will be fine, but beyond 5mm your chances of creating a good clean and straight cut start to diminish.

Similarly, you’ll need at least 150mm of glass on the side away from the piece you want to make it a successful cut. Finally, you’re advised to limit the size of glass sheet that you want to cut to about 500mm, beyond that length it becomes difficult to prevent a corner of the piece of glass you want from shearing off.

Glass Cutting Tools

The essential tool for cutting glass is a diamond or tungsten tipped cutter. For most occasional domestic glass cutting purposes a good quality single wheeled glass cutter from your DIY store will be fine.

Glass cutters can have up to six wheels on them and the more wheels they have the better and deeper they can cut. Even so a six wheel cutter will only work up to a depth of 6mm.

To cut circular holes in glass you’ll need to buy a specialized tool simply called a circular glass cutter. Before using a glass cutter make sure the wheel(s) turn freely.

    Safety: Be sure to wear eye protection goggles and think gloves when workinh with or cutting any kind of glass. Even though most glass is tempered to prevent shattering, it can still give you a nasty cut.

Cutting Straight Lines

-Making sure the glass is clean and void of any obvious blemishes or cracks, lay the glass on a good flat surface then using a metal, or engineers, ruler measure and mark the cut to be made with a crayon or china marking pencil.

-Holding the metal ruler firmly along the line to be cut, score along from one edge of the glass sheet to the other with the glass cutter in one continuous movement, applying the same pressure throughout.

-Lift the glass at one end and, with the handle of the glass cutter, gently tap along the score mark you’ve just made.

-Place a thin piece of timber batten, or wooden ruler, under the glass sheet with one edge on the scored line.

-Holding the glass firmly on one side apply pressure to the other to snap off the surplus. Thin strips can alternatively be snapped off using your thumb and forefinger.

If necessary trim the cut edge with the cutter notches or a nibber.

Cutting Circular Holes in Glass

To fit a louver or extractor fan you might want to cut a circular hole in glass.

- With a crayon or china marking pencil, mark the center for the hole to be cut, and then draw diagonal lines through that point to where the circumference of the hole will be. Measure the diameter of the hole that you want to cut and add 2mm, set the circular glass cutter arm to half of that measurement.

- Attach the cutters’ suction cup so that it is exactly over the center point previously marked.

- In one continuous movement, and applying equal pressure throughout score the cutting wheel around the desired circumference then gently tap the under-side of the cut with a glass cutter.

- Reduce the radius of the cutting arm by 20mm and score a second circle - inside the first, again gently tap the underside.

- With a conventional glass cutter score across the diagonals of this inner circle, the more diagonals you score the better.

- Support the newly scored sections with a hammer and tap them out gently.

- Then score lines from the outer circumference into the hole just created and tap out the glass sections, finally tidy up the newly created edge with a nibbing tool or the notches of a cutter.