 | Bob Crager of Lewis Street Glass is a 26 year veteran in the glass business. Lewis Street Glass is a leading Wichita Glass company, serving the entire Wichita/Sedgwick County area since 1919. They do anything and everything having to do with glass, both residential and commercial. They also do Auto glass. They are located at 743 South Market, facing Kellogg on the South, and you can reach them by phone at (316) 263-8259. You can email Bob Crager at bcrager@lewisstreetglass.com |
Glass
2004-07-01 10:52:00
Cutting Glass... continued
Question: How does one go about cutting glass?
ANSWER: This will complete the series on cutting glass. For the entire series, please refer to March, April, May & June. RUNNING THE SCORE Running the score is when you bend the glass through that 1-degree arc to get it to break. This can be as simple as taking the glass in your hands, and just "breaking" it. Put your hands into fists, thumbs up. Now, the glass will go between your curled index fingers on the bottom, and your thumbs on top. Get a good grip, knuckles nearly touching, and bend and pull apart at the same time. The glass will snap right along your score line. This method is good for pieces that are large enough to get a good grip on, and that have a straight, or only mildly curved score. Another way to run the score is with "running pliers." These have (as you're looking in from the business end) a convex surface on the bottom jaw, and a concave on top. As you center these pliers on your score, the bottom jaw makes contact only at the score. The top jaw makes contact about 1/2 inch on either side of the score (the jaws are about an inch wide). As you squeeze, the pliers separate and widen the score, and the "fissure" created then follows right along the score. This gives a much more controlled break than the previous method, and is almost a necessity for tight or multiple curves. There are a couple other methods that I'll just touch on here:For straight scores, you can extend the glass off the edge of a table. With the score just off the edge, hold pressure on the tabled section, and just snap down on the free piece. If you score a piece of glass, and turn it upside down on a piece of cardboard or other springy material, you can exert thumb pressure directly over the score, and it will run. This method is helpful sometimes when you have multiple curves, you've used the running pliers from both ends, but the run just won't quite make it all the way to the middle... A little pressure like this will usually finish the job. When necessary, you can also cause a score to run by tapping its reverse side. This method is rather inconsistent and should only be used as a last resort. There is a glass cutting "system" put out which uses plastic buttons, and a piece of concave plastic. Here you put the score directly over the button, and use the concave piece above. It's basically free-form running pliers, only there are no handles or a hinge. The last way to shape a piece of glass isn't so much running a score as it is nibbling small bits away up to the score. It's called grozing, and is used primarily on tight inside curves. You can use regular pliers for this, but there are specially designed grozing pliers that do it better. Before glass grinders, grozing was used for final shaping of pieces that needed "just a hair more off here, and just a touch over there." All you need now is a piece of glass, a cutter, and a couple of practice runs! SAFETY GLASS There are two kinds of safety glass: The first type is tempered. This means that the glass has been cooled in such a way to induce tension in the exterior skin, while the interior is in compression; much like a balloon. The bottom line is that cutting tempered glass is like cutting a balloon. It just can't be done (unless you first anneal the glass, cut, and then re-temper, in which case it would be cheaper and easier to just start with annealed glass in the first place). The second kind of safety glass is laminated. This is actually a sandwich of two sheets of glass with a sheet of plastic between them. In order to cut this kind of glass, you need to score one side, and run the score by tapping. Then flip it over and do the same thing on the opposite side. Apply a flammable liquid such as alcohol or lighter fluid and light it. As the plastic begins to warm and soften, you can pull the pieces apart. Pull directly apart and don't let them "hinge" if you care about what the edges will look like.
