Tools and Machinery of the Granite Industry, Part III

The hand polisher was suspended from a chain fall hoist attached to a trolley that ran along the top of the swinging horizontal boom of a crane. The hoist allowed the operator to raise and lower the polisher. The polisher head was belt-driven from an electric motor mounted directly on the suspended polisher frame. The operator stood on a four- to five-foot high wooden platform and could move the polisher to reach two workstations. He could be polishing the sides and top of one die while a second was being set in place. The hand polisher was used to polish the sides of large dies, to polish curved surfaces or tight places, and to polish out scratches and nicks.

Granite polishers have evolved into very sophisticated computer-controlled multi-head polishers with contained abrasive blocks such as the French-made Thibaut twelve-head continuous polisher that automatically moves the granite from one polishing stage to the next and can polish two hundred square feet of granite per hour. One of the most complex and most capable automated granite-working machines, the Thibaut GB110, grinds, shapes, routs, drills, and polishes.

Splitting

Given a number of outstanding orders, the shed foreman would look for a slab of a certain thickness and granite type to fill some of the orders. After measuring with a rule, he would ticket the selected slab. Later, a lumper would come along and dig out the ticketed slab-sometimes having to move a half dozen slabs to get at it. The layout man, who was often also the shed foreman, following dimensions on the shop tickets, would then mark the cut lines on the slab with chalk in such a way to insure minimum waste. Then he and a helper, known as the breaker, would cut it using a slab splitter and striking hammer. For a very thick slab, it might be necessary to drill holes along the chalk lines and split the slab using wedges and shims. Later, when wire saws and diamond circular saws became available, they were used to make these cuts. Today, the hydraulic slab splitter ("hydrosplitter") is used for this job. It consists of a bed on which the slab rests and a pair of hydraulically powered knives, one positioned above and the other below the slab. The enormous forces (20,000 psi) applied to the slab by the knives splits the stone in a fraction of a second.

Roughing Out and Cutting

Stonecutters were usually the most numerous of the granite workers in a shed. Each stonecutter worked at a banker-a bench consisting of saw horses or wooden blocks to support the stone being worked on. Normally, the stonecutter stood as he worked, with his whole body involved in the work. Occasionally, a neighboring stonecutter might help (Figure 34), and for a really large stone, two or more stonecutters might work at the same banker. Each banker was supplied with compressed air through a hose with various couplings connected to the stonecutter's pneumatic hammer. A banker might also be supplied with water, and by the late 1930s, had a suction device, called the banker dust collector, for the removal of airborne granite dust (Figure 35). Carvers also worked at bankers and, although fewer in number, usually worked side-by-side with the stonecutters.