The history of sawing granite
Author:alvin Date:2/11/2009 7:50:19 PM Read:2579
Although early metalsmiths learned how to increase the hardness of copper, granite was still over four times as hard. The very hard sand particles imbedded themselves in the copper blade and were dragged across the surface of the stone, abrading and wearing it down along the narrow kerf. In the process, the copper blade was also worn down and eventually had to be replaced.
Stone saw technology passed to Ancient Greece and then to the Roman Empire, shifting to iron and water-powered saws.
Perhaps the earliest stone sawing in Vermont occurred in the early 1800s at Dr. Judds marble works in Middlebury, using soft iron blades with sand and water abrasive. The swinging frame gang saw was later introduced in Rutland for sawing marble. At its peak, the Vermont Marble Co. had 63 gang saws running day and night at their Sutherland Falls mills.
Rowland E. Robinson recalls a visit to this mill. "The sawing-mill is not a cheerful place. Dampness pervades it, and under the low roof stretch the long dim vistas, ending in gloom, between the gangs of incessantly swinging saws. … The machinery growls and hisses as it gnaws the stone like some monstrous beast in its den over its prey, and hardly another sound is heard."
Lincoln Iron Works and F.R. Patch Manufacturing Co., both of Rutland, were the major suppliers of gang saws to the marble industry and later to the granite industry.
The gang saw was typically the first stop for granite from the quarry, cutting a quarry block into slabs ranging from a few inches to a foot or more in thickness. In 1909, Jones Brothers operated two gang saws manufactured by Lincoln Iron Works. They consisted of a reciprocating frame with six or so cutting blades. A single electric motor powered both saws via flat belts from a single overhead shaft. Jones Brothers fabricated their own saw blades from 16-foot by 16-inch steel blanks. A pattern with notches about 2-inch wide, 3 to 4-inches deep, and spaced 4-inches was used to mark notches on the steel which were then cut out with an acetylene torch. Blades would last about a month in continuous use.
The gang saws usually ran 24 hours per day with two-man crews. They were noisy machines – making dragging and screeching sounds that could be heard a mile or more from the shed.
In the late 1800s, chilled iron (and later steel) shot abrasive greatly increased the sawing rate. After sawing was complete, each slab was separated, chained, laid down and acid washed to prevent rust staining. This was an unpleasant (and probably unhealthy) job with acid fumes forming a smog cloud!
Circular blade saws were introduced in the 1860s for jointing and ripping slabs into smaller-sized pieces. The circular saw blade had either riveted-on steel tooth segments or set-in diamond tooth segments. By the turn of the 20th century, F.R. Patch Manufacturing Co. was manufacturing a gantry diamond circular saw with a 6-1/2-foot diameter blade that spun at 500 rpm.
Cook, Watkins & Patch of Barre had one of the first steel-tooth circular saws in Barre and since there were very few of these saws, they did sawing work for many other firms. The saw cut a very rough surface so afterward the surface had to be dressed with a surfacing machine.
Wire saws were introduced into Barre by the Dessureau Brothers in the late 1940s and early 1950s. The multi-wire saw with six to eight wires soon replaced the gang saw for granite slabbing since the wire cut faster, was quieter in operation, and produced a narrower and smoother-sided kerf.
The wire loop was often 4,000 feet or more in length in order to prolong the life of the wire. The loop was supported on large-diameter sheaves running in a line as much as a half mile from the shed or sometimes between a wheelhouse and tail house on the shed roof. Typically, the wire had to be changed every day or every other day.
During the late 1930s, 40s and early 50s at least 18 saw plants were established in Barre to provide sawing services for sheds without their own saws. During the 1950s, the Marr & Gordon saw plant operated a gigantic Lincoln Iron Works gang saw – reputedly the largest east of the Mississippi. Most saw plants did only sawing. A few saw plants also did polishing so they could offer polished slabs to their customers. Saw plants were quite profitable and some like the Rouleau saw plant used saved profits to later establish successful granite finishing businesses.
Before World War II, most saw plants were using gang saws and a few were also using circular saws to cut small pieces. After World War II, most saw plants changed to wire saws and finally in the 1970s to large computer-controlled circular saws with up to 13-foot diameter diamond segment edged blades. A 12-foot diameter blade has about 160 diamond segments and can saw about 15 square feet per hour. These saws run 24 hours per day, unattended during nights and weekends. The computer notifies the operator at home by telephone if there is any problem.