Cutting rock can produce beautiful pieces for display, jewelry and home use. Using the proper tools and techniques for cutting stone make the process go more smoothly, preserves tools and creates attractive pieces. There are tools for cutting small gemstones and others for cutting larger stones such as granite, but there are similarities in the tools and techniques used for each.
Diamonds are the hardest substance on earth, so diamond saw blades, diamond wheels, drill bits and hole saws will cut any kind of stone you have. While you do not need to use a diamond blade for soft stone, if you are not sure how hard the stone you have, a diamond blade is the safest choice. Besides being able to cut any stone, diamond blades are long-lasting. If you know the stone you are using is softer, such as limestone, soapstone, travertine, barite or flourite, it can be cut with a hard metal or carbide saw blade.
Use a Cutting Fluid
Even a diamond saw blade will stop working after only a few minutes if the user does not keep the blade cool and sharp with a cutting fluid. Although some craftsmen, especially in the past, used kerosene or diesel fuel as a cutting fluid, this is not a good idea because it is easily flammable and hard on the skin. However, for hard stones, such as quartz-based agate and jasper, oil is the only cutting fluid. Buy proper oil-based cutting fluid that has a high flash point (so that it doesn't catch on fire easily), low viscosity, no carcinogens and low odor. Look at lapidary supply houses for good oil-based cutting fluid.
Water as Cutting Fluid
Water works as a cutting fluid for some softer stones such as turquoise, marble and granite. Water is effective if the stones are abrasive, if they clean the blade as it cuts and leave little residue and do not generate heat. Also, oil cutting fluid will penetrate porous stones, so water is the preferred cutting fluid in those cases. If you use water, be sure to drain the stone saw and dry it after you finish each day. Use a rust inhibitor on the saw after you dry it.
To keep your saw blade sharp and working well, use a sharpening stick or an old silicon carbide 100-grit wheel. If your saw blade is dull, clean away the metal to expose new diamonds by running several cuts into the sharpening stick or the grit wheel. Using a loupe, check the edge of the blade. You should be able to see two or three diamonds in each blade notch. They will look like small, black dots.
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