Content provided in partnership with
Tools and Machinery of the Granite Industry
Chronicle of the Early American Industries Association, Inc., The, Jun 2006 by Wood, Paul
Two types of holes were drilled-vertical deep holes forming the sides and back of the quarry block to be extracted and horizontal lift holes forming the bottom of the block. These lines of holes were indicated with marking chalk, which was usually blue or red in half-globe cakes or square blocks, by the head quarryman. The holes were typically one and one-quarter inches in diameter, twenty feet deep, and spaced six inches on center. This resulted in a cube-shaped quarry block twenty feet on a side weighing about 680 tons (Figure 17). Initially, quarry drilling was a manual operation using a hand drill and drilling hammer (Figures 18 and 19). For the deep holes, one quarryman held the drill and one (called single jacking) or two (double jacking) quarrymen swung the drilling hammers with the drill-holding quarryman rotating the drill slightly after each blow (Figure 20). It is believed that the terms single and double jacking came from "Cousin Jack," a nickname for a Cornish miner. The drilling hammer had two beveled-edge striking faces and weighed three to four-and-a-half pounds. Hand drills came in graduated lengths and had either a star-shaped or flattened cutting head. Periodically, a deep hole mud spoon (Figure 21) was used to clean the powdered granite from the hole. For the lift holes, either a granite surface was available for the quarryman to stand on or scaffolding was erected on the face just below the intended line of drilled holes (Figure 22). The quarryman held and rotated the drill as well as swung the drilling hammer. In a Michigan hand drilling contest, a double jacking team drilled a fifty-nine-and-one-half-inch deep hole in Vermont granite in fifteen minutes. In a Colorado contest, a quarryman single-handedly drilled a twentysix and five-eighths-inch deep hole in Colorado granite in fifteen minutes.
Steel granite-working hammers came in three basic varieties. Some hammers, like the drilling hammer, were designed to be swung and to strike steel graniteworking tools of various kinds; other hammers were designed to be swung and to strike the granite directly, and finally, some hammers were designed to be held in place against the granite and to be struck by another hammer. In any situation where steel strikes steel, the hammer striking face is both tempered to provide impact resistance and beveled to reduce the chance of splintering. Granite workers are now required to wear protective glasses or goggles to prevent steel splinters from flying into their eyes. Repeated use causes striking faces to "swell" and thus need to be periodically ground back into their original shape. Hammer handles were usually made of hickory and were of various lengths, cross-sections, and shapes depending on the hammer size and use. Today, the buyer can order fiberglass handles as an option for most granite-working hammers.
Joseph Couch of North Bridgewater, Massachusetts, was issued the first patent for a steam-powered rock drill in 1849 (Figure 23). The patent describes a reciprocating percussion steam-powered rock drill. The drill, which weighed several thousand pounds, was mounted on a portable wheeled frame and could be adjusted to any angle from horizontal to vertical. Power was imparted to the drill bit from a steam cylinder by a gear and crank mechanism. A cam and wedge device grasped the drill bit during its forward motion and released it at its moment of impact with the stone. This was the first drilling mechanism that did not depend solely on gravity for the drilling stroke, and therefore, the first one that could be applied to other than vertical drilling. The drill bit was rotated after each impact. In 1852, Joseph Fowle of Boston, Massachusetts, was issued a patent for a less cumbersome version of the Couch drill. Fowle's design included the important innovation of the drill bit as an extension of the piston rod.
Find Research Guides for:
Find Featured Titles for: Home & Garden
Most Popular Articles in Reference
- The importance of understanding organizational culture
- Credit card attitudes and behaviors of college students
- What factors attract foreign direct investment?
- Libraries Need Relationship Marketing - mutual interest marketing concept, ...
- How to set performance goals: employee reviews are more than annual critiques
- More »