How to cut glass
Wash and thoroughly dry the uncut glass to remove any particulate matter that might impede the wheel of the glass cutter.
Delineate the shape you want to cut by either taping a pattern to the underside of the glass or tracing the pattern onto the glass with a grease pencil. Select shapes that can be cut out in a series of straight or nearly straight lines until you are comfortable with the way glass scores and snaps.
Position the glass cutter on the surface of the glass, with the cutting wheel directly perpendicular to the surface.
Start at one edge of the glass sheet and score it lightly with the cutting tool along your pattern's longest straight line all the way to the other edge of the sheet.
Snap the glass by placing a pencil under the score line and applying equal pressure to the glass on either side of the pencil.
Place the cutter at the newly created edge along your pattern and score a straight line along your pattern all the way to the other edge of the glass sheet.
Snap the glass along the second score line by again placing a pencil under the glass along the score line and applying equal pressure to both sides of the pencil.
Continue to score along your pattern from the newly cut edge to the far edge of the glass sheet. Don't be surprised if this process of scoring all straight lines means that at times you are cutting the glass away from very small sections of your actual pattern. A series of straight cuts, as opposed to one or two sweeping curves, will always yield cleaner cuts that are significantly more likely to snap where you want them to.
Continue scoring and snapping the glass sheet in straight lines from edge to edge along your pattern until you have completely freed your pattern from the surrounding glass. cnc glass cutting machine