About the simplest and most useful process for you to know is how to cut glass.

To cut window glass you need (1) a glass cutter; (2) a drawing board and (3) a T square. There are two kinds of glass cutters on the market and these are (a) steel cutters and (b) diamond cutters.

The first kind has a little steel wheel in the end, as shown at A in Fig. 83. You can buy one for a quarter and it will serve all your needs very well. If money is no object you can buy a glass cutter with a diamond point such as glaziers use for about $4.00. This kind of a glass cutter has a chip of genuine diamond in a swivel end and it is a pleasure to cut glass with one of them. It is shown at B.

90 An achromatic lens is one that is free from color.

91 Cobalt is a metal and is usually found along with nickel.

92 Uranium is also a metal.

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Fig. 83. Glass Cutters

A. A steel wheel glass cutter.

B. A diamond point glass cutter.

How to Use a Glass Cutter

"There are tricks in all trades but ours," said the carpenter as he drove in a screw with a hammer, and so if you will dip the steel wheel cutter into some kerosene before each cut is made you will be surprised to find how easily it cuts.

To use a diamond cutter, hold it just as you would hold a pencil and grip the three sided part with your thumb, index and middle fingers, as shown at C. Then place the cutter against the straight edge of your T square, press it down firmly on the glass and draw it along evenly.

To make the right kind of a cut hold the diamond at a sharp angle, that is, very slanting, and raise it slowly until a smooth, sound and clear cut is made. Don't hold it straight up and down or you will surely spoil it, and never never cut twice over the same line.

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Fig. 83C The Right Way To Hold A Diamond Point Glass Cutter

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Fig. 84. How To Cut A Pane Of Glass

It takes more skill to use a diamond cutter the right way than to use a steel cutter, but a little practice will make you proficient.

When you want to cut a sheet of glass lay it on your drawing board with the blade of the T square on it and the head of it against the edge of the glass as shown in Fig. 84; hold it tight and then make a good, clean cut. You can then easily break the sheet of glass along the cut if there is enough glass on each side of the cut to get a firm hold on. If not put it into one of the notches on the shank of the glass cutter and you can then easily break it off.

How to Finish Off Glass Edges

When you cut a sheet of glass the edge left by the cutter will be slightly rough. To smooth it up and round off the corners rub it on a whetstone, that is any kind of a coarse stone on which you have poured a little water. A better way is to grind it on a grindstone if you have one.