Tools and Machinery of the Granite Industry

Charles Burleigh of Fitchburg, Massachusetts, and others were issued an 1866 patent for a number of improvements to the basic Couch/Fowle design-resuiting in the first practical and reliable steam drill (Figure 24). It was successfully used to drill the Hoosac Tunnel, the first mechanically bored American tunnel. Later, Burleigh bought the Fowle patent, which his drill infringed, and organized the Burleigh Rock Drill Co. In 1871, Simon Ingersoll of Brooklyn, New York, was issued patents for a feed rod/plunger/ratchet/wheel-nut combination that produced an automatic feed, for a supporting tripod drill stand with independently adjustable legs, and for a spiral bar to rotate the drill bit during operation (Figure 25). Henry Sergeant of New York City was issued an 1873 patent for a steam or pneumatic drill in which the drill bit was an extension of the piston rod. Sergeant claimed the improvements-rotating valves, cushioning piston stop, a new mechanism for revolving the drill bit, and automatic feed.

The widespread introduction (circa 1870s) of the steam quarry drills revolutionized the quarrying operation. Although steam drills were used up to the 1920s, pneumatic quarry drills began replacing steam drills by the early 1900s. The heart of the mechanical quarry drill is a mechanism called the valve, which directs the steam or compressed air alternately to the back and front of the drill piston. There were many valve designs, including unbalanced spool, tappet, auxiliary, butterfly, and ball and disc. Charles Burleigh had the first really successful drill that was manufactured in quantity. The Burleigh design had a piston with a slight hourglass-shaped curvature and piston rings at each end. It had a rod attached to the front of the piston that projected through a packing gland. The end of the rod was coke-bottle shaped and bored out at the end to accept the drill bit (or drill steel) (Figure 26). A chuck with a U-bolt clamped the drill bit onto the piston rod. It also included a rifle bar device with a series of pawls to rotate the drill bit after each blow. This drill, in which the drill bit is connected directly to the piston, is called a piston-type drill and can achieve about six hundred blows per minute. Drill bits were sold in sets of increasing lengths. When the hole depth reached the length of the drill bit, the next longer drill bit was used. A drill bit set advertised for the Rand no. 5 steam drill consisted of a dozen octagonal shank, cruciform head drill bits in two-and-one-half-foot increments from two and one-half feet to thirty feet.

In 1898, John Leyner of Denver, Colorado, made two important improvements to the quarry drill, a drill bit that was no longer connected to the piston and a hollow drill bit to allow air or water to flush out the cuttings (Figure 27). The piston rotated with each blow and an attached chuck held and rotated the drill bit. Called a hammer-type drill, it could achieve fifteen hundred blows per minute since it did not have to overcome the mass and friction of a long drill bit. With this drill, the bits could be easily removed and sent away for sharpening without taking the drill out of service. A blow tube, that carried air or water, ran through the center of the drill piston and its hammer head projection and into the hollow drill bit. Thus, the air or water was carried to the bottom of the drill hole where it flushed out the stone cuttings. Piston drills produced a pumping action of the drill bit that moved the cuttings out of the drill hole. Hammer drills could not do this since the drill bit did not move with the piston, and so cuttings would build up in the hole. Therefore, until sufficiently strong hollow drill bits could be manufactured, the hammer drill was primarily used for mine ceiling stopeing where the cuttings would fall out of the hole by gravity. Rock drills, which emit a thunderous roar and produce large quantities of airborne dust are, without protection, hazardous to human health. Today, quarry drillers normally wear double ear protection. Wet drilling, made possible by Leyner's invention, greatly reduced the amount of airborne granite dust and saved the lives of thousands of quarrymen and miners. Before this time, mechanical quarry drills were called "widow makers" since many quarry workers succumbed to early deaths from silicosis induced tuberculosis.