Reply To: Glass Cutting
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Cut the glass on a flat surface. The surface should be covered with something like an old piece of carpet/rug, not a deep pile one though. Use a good glass cutter. score the glass once only. if the cutter sounds like a machine gun as it score the surface or seem to be sliding rather than rolling over the glass, change it, or use a new wheel if you are using a multi wheel cutter. There are a number of ways to open the cut, it depends on the thickness of the glass and distance from the cut to the edge. For most glass up to 5mm or 6mm and with about 10″ or more either side of the cut; the cut can be opened by placing the sheet of glass on the edge of the bench/table (whatever you are cutting on) with the cut no more than 3mm back from the edge. Then, press down gently on the glass where it rests on the table and holding the other edge glass with the other hand, push down firmly and quickly. The glass will break cleanly along the cut.
If there is less than 10″ and more than 2″ between the cut and the edge, place a narrow and thin (no more than 6mm) piece of wood under the glass so that the cut is in the centre of the top surface of the wood. Press down firmly and evenly on each side of the glass and it will break cleanly along the cut. If your piece of wood is shorter than the length of the glass, place it equidistant from each end of the cut.
If you are taking less than 2″ off the edge of the glass, but more than 1″, sharply tap the under side of the cut at one end with the glass cutter, there is usually a head on the end of the handle of the cutter for doing this. If you are using a wooden handled cutter, use the metal part where the wheel/s are. The glass will crack along the cut for a 1/2″ or so. It does not take much power to open the cut this way. Now, either slip a narrow and thin piece of timber under the edge of the glass as described above, but only about 1/4″ / 1/2″ should be under the edge, then press down on both sides of the cut near the edge of the glass. If you apply the pressure gradually, you will be able to see the cut opening along its length.
If you are taking less than 1″ you can tap the underside of the glass as above and then use one of the notched in the head of the cutter to bend the glass and open the cut. Hold the glass so that the 1″ or so of the glass is over the edge of the bench, slip the glass edge into the notch in the cutter (handle pointing straight up), next to the point where you opened the cut by tapping, this positioning is important. then pull the handle of the cutter like a lever and the cut will open. If the glass is too thick to fit the notch you can use a pair of pliers to grip the glass. Make sure you have a piece of thin cloth between the metal of the jaws of the pliers and the glass. You can get special glass pliers for this, they have jaws that are about 1″ wide so have more surface contact with the glass and spread the force. Inside the jaws of the glass pliers there are small grooves. These pliers can be used to grind off the “waney” edge you get when opening the cut by tapping.
If you want to know how to cut a round hole in a sheet of glass, I can tell you how to do it. No its not like you see in the movies. Pulling a disc of glass out of a window is impossible and you cant open a cut from the same side as you score it. You cant cut glass that has been toughened by heat treatment either. You can cut laminated glass with a hand cutter, but its tricky.
Finally: never try to catch a piece of glass if you drop it, you will get cut.