Hi, I am Phillip McKee of McKee Stained Glass, right now we are going to learn how to take a pattern piece that we have cut out of glass and turn that into a smooth edged piece of glass that we can safely handle and that will be ready for incorporation into a larger finished work. Once you have cut out a pattern piece, there will be sharp edges at corners, where there are joints of curves and also inside the curves themselves. When glass is cut, it does not always cut in nice clean break, instead a small sharp edge can sometimes form. Those edges can be sharper than a scalpel and will slice into you very efficiently. Because of that, always avoid grabbing your pieces on the inside curves or shoving your fingers into them. Instead, attempt to pick them up on flatter surfaces and cradle them gently as you move to grinding.
There are several ways to grind your pattern piece and smooth the edges; the oldest method is using the Breaker/Grozer pliers to chip away at the pieces. This is called grozzing. Once again, we want to make sure that we wear our safety glasses. This time hold the grozers curved side up. Take the same grip as you had before, bite onto a pointy section that you wish to remove, squeeze tightly and pull. The points will be removed and you will have something that more closely approximate the curve. This method will help fine-tune a shape, but it will not really smooth the edges. Well, that would be useful when working with lead or zinc channel. Since we are going to be using the copper foil method, we need completely smooth edges; otherwise the glass will tear the foil.
To get completely smooth edges, we can either use a carborundum stone, which is an alumina silicate stone that is manmade. These stones when rubbed along the glass will smooth it. Allowing it with the smooth edges and also fine-tune shapes. However, as you can imagine, this can be very slow and time consuming. The preferred method is to use a power grinder. There are several different types of power grinders. This particular one is known as a router style power grinder, in that it has a central spinning bit against which our glass piece is pushed, by applying gentle pressure, the grinder bit which is covered with diamonds removes excess glass and provides a nice smooth frosted edge.
Another type of grinder is a disk grinder in which a flat disk spins. That can be very useful when grinding straight lines. Since all you have to do is apply straight downward pressure. Finally there are belt sanders and belt grinders, which are actually the oldest type of grinder. These look like standard wood belt sanders, except they have diamond grit and like all other glass grinders, have a water reservoir that lubricates the diamonds and allows for more efficient grinding. It is also a good idea to add grinder coolant for your grinder. First, when you are going to grind, check to make sure that your grinder has water. I have my grinder hooked up on a foot switch for ease of use, otherwise you will need to turn it on and off with each turn. To check if your grinder has enough water, feel the sponge to see if it is wet.
If it is wet, then turn it on and place your hand behind the grinder, you should get water on your hand. If water is not flowing from the grinder, then you need to check your reservoir and make sure that it is up to proper fill level. Since water sprays from the back and the sides of the grinder as you are grinding, as will some glass dust material, that once it dries turns into a hard pasting glass mud. You probably do not want your grinder to be spraying over all of your equipment. Normally you place a screen around your grinder. In this case I have removed the screen so you can actually see what I am doing. Your first step when grinding is to give a general smoothness to the edge of the glass simply to remove the hardest, sharpest edges. That way you can grind successfully without injuring yourself to do that. Place your fingers on top of the glass, turn on your grinder and very carefully rub along all the edges.
This does not have to be very slow, do not expect to change the shape much. Now we are ready to begin removing some of the excess glass especially where we had the joining of the two curves. Once again, we turn on our grinder and we begin moving back and forth never hold the glass in one place, always move back and forth. So that you get nice, smooth continuous lines, pay special attention to the corners, so that they do not have any excess sharp places that could damage your foil and move back and forth until you are done. The reason I say not stay in one place for any length of time is you can actually grind out a section in the profile of your grinder bit. If you sit in one location and push too hard, here is what I mean. We have a flat section on the tail, what would happen if I hold it in place for too long?
I no longer have a flat tail, when you are done grinding, wipe your piece clean and you are ready to move on. Next we are going to learn, how to convert a paper pattern into a piece of cut glass.
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