Tools and Machinery of the Granite Industry, Part IV

Each tool-grinding machine consisted of two, 5-foot diameter grinding wheels and was used for sharpening hand chisels and surfacing-machine bush chisel cuts (Figure 28). A continuous stream of water was applied during sharpening. The grinders were powered by an electric motor via overhead shafting and flat belts. Two sizes of pulley were provided for two grinding speeds. High speed was used for sharpening bush-hammer cuts. The grinding wheels were normally located in a shed alcove or a small shed attached to the large shed so as to be conveniently near the stonecutters. There was a constant movement of tools between the stonecutters and sharpeners, carried by tool boys. After the advent of carbide-tip tools circa 1950, grinding wheels composed of a material specifically designed to grind carbide (for example, National's "Natalon") were used to grind worn carbide tips. Carbide tips were ground but not quenched like a steel-tipped tool. Grinding was intended to bring the carbide tip back to its original shape-with edges not too sharp or pointed and corners slightly beveled to prevent carbide breakage. Today, worn carbide tips are replaced and not sharpened.

The Pirie disc-sharpening machine, designed by Willis A. Lane of Barre, Vermont, sharpened the cutting discs for the stone-cutting lathes and, at an earlier time, the cutting discs for the McDonald mechanical surfacer (see Figure 2). It had a large 8-inch wide, 4 ½-foot diameter grindstone that moved back and forth on its axle as it turned (Figures 29 and 30). This ensured even wear on the grindstone. After sharpening on the grinder, the discs were sent to the blacksmith shop for tempering.

Most medium- to large-size granite companies had a machine shop with several trained machinists (Figure 31). This shop would normally be furnished with several metal-working lathes of different sizes, drill presses, grinders, workbenches, welding equipment, a steel-top welding bench, and storage for metal stock and spare parts (Figure 32). None of this equipment was specific to the granite industry. The shop could repair just about any machine in the shed. The head machinist often designed custom machinery or modified existing machinery to meet special needs. Hence, the equipment inventory of a typical large shed included both standard manufactured machinery and many custom-designed and built machines.

Evolution of Power Sources

Since granite is a tough and heavy material, the availability of power for quarrying, finishing, and transport was critical. The basic problem was the conversion of energy from various sources (draft animals, falling water, and burning wood or coal) into motive power and then transmitting that power to the granite-working and moving machinery. The cost of power was typically only a small part of the total cost of a granite operation, but it was a critical part. Any power interruption could shut down the entire manufacturing process. Granite became a major nationwide industry only after the introduction of highly efficient tools and machines and the availability of reliable power to run them. In the end, the choice of a power source depended on the scale of the granite operation, the number and size of local water power sites, the local availability and cost of fuel, and the possibility of sharing power sources with other local industries.