STONE CUTTING AND DRESSING. Processes employed in preparing quarried stone for structural and ornamental purposes. These processes range in character from the rough shaping of the stone into squared blocks, which is generally performed at the quarry, to the cutting and polishing of carefully modeled and orimmental pieces such as columns. cornices moldings, and balustrades, and they may be carried out either by means of hand tools or by stone-working machines. The hand tools used in stone cutting and dressing are various shaped hammers and chisels and simple forms of measur ing instrumentA, templates, and gauges.
After a block is broken from its quarry bed by one of the methods described in QUARRYING, it is trimmed to the desired size and shape by a variety of means according to the hardness of the stone and the kind of finish desired. By means of the pitching chisel the rough block is trimmed down to a line, then the irregular surface is worked down by the point, after which it is finally dressed. If the stone is to be polished it is first scoured with wet sand. Small blocks are now usually ground with wet sand on a re volving iron bed, while large blocks are ground by dragging a slab of stone back and forth across them with wet sand as the abrading ma terial. For securing a finer polish, emery, hones, pumice stone, and polishing putty (oxide of tin) are used. A high grade of polish can be secured by skilled workmen only, and each man usually has his own peculiar methods for securing the result desired.
In most large establishments grinding and polishing machines are much employed. For flat surfaces a circular horizontally revolving iron plate or grating, attached to the lower end of a vertical shaft, with an elbow joint. is used, the workman guiding the plate to various parts of the surface, and using sand or emery as the abrading material. By attaching felt to the plate the same machine is used for polishing. Blocks of such small size as can be handled by the. workmen are usually ground upon horizontally revolving iron beds stone eight or ten feet in diameter. Pendulum machines are used for polishing simple moldings. The molding being first cut as smoothly as possible with the chisel, a plate of cast iron, fitted as accurately as pos Bible, is made, by means of a long arm, to travel back and forth along the molding, with sand, emery, putty powder, or other abrasive.
For turning posts and pillars lathes are now generally used. For the softer stones a simple pointed cutting tool similar to that used in turning metals and held and operated by a simi larly constructed machine is employed. In turn ing hard stones like granite the cutting tool is in the form of a thin steel disk some 6 inches or S inches in diameter, so arranged as to revolve with the stone when pressed against it at a sharp angle. Lathes of this type are used, which are capable of turning a block 25 feet long and 5 feet in diameter to a perfect column. Planers for rough work, such as flagstone, resemble the same machine for planing metals. See METAL-Woak ING MACHINES.
Stone-sawing machines are made in various forms. The most familiar form consists of a smooth flat blade of soft iron which is given a reciprocating motion by machinery and fed with sharp sand and water. Such saws are commonly worked in gangs of ten or a dozen blades set parallel the desired'distanees apart and operated by a single saw frame. This method of sawing is not applicable to cutting granite, on account of its hardness. Frequently, in place of sand, use is made of small globules of chilled iron or of crushed steel as an abrasive. Circular saws set. with diamonds have proved very efficient tools, but their use is generally prohibited by'their ex pense. Slate is sawed by circular saws such as are used for sawing lumber. In Europe con siderable use has been made of twisted cords of steel made to run around pulleys like a band saw. Among other machines for stone cutting and dressing mention may be made of pneumatic hammers and the sand blast.
BIBLIOGRAPHY. The literature relating to Bibliography. The literature relating to stone cutting and dressing is somewhat scattered. Two books which may be consulted with advan tage, however, are: Merrill, Stones for Building and Decoration (New York, 1891), and Baker, Treatise on Masonry Construction (New York, 1900).