A popular top polisher for polishing the curved tops of monuments, the vertical polishing machine, was introduced around 1890 by the Concord Axle Co. It was suspended from an overhead shed beam and had a 10 to 20-foot long telescoping vertical main shaft with bevel driving gears and a universal joint at its top. The polishing wheel was attached to the bottom of the shaft with a second universal joint. The polishing wheel could be raised and lowered with a counterbalancing weight to make movement easy. The polisher had many degrees of freedom – the polishing wheel could be moved to any point on a horizontal plane, could be moved up and down, and could be tilted to any angle, allowing polishing of curved as well as horizontal or slanted flat surfaces.



Initially, all the polishing machines in a shed were powered by a single waterwheel via a millwork of shafts, belts and pulleys. Later the waterwheel was replaced by the water turbine, steam engine or electric motor. As the size of electric motors decreased, a motor was dedicated to each polisher and the power was transmitted via belt and pulleys or shafts and gears integral with the polishing machine.



The suspended polisher was introduced to polish the sides of large dies, to polish curved surfaces or tight places, and to polish out scratches and nicks. This polisher was suspended by cable 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 to operator to raise and lower the polisher. The polishing wheel was belt-driven from a counterbalancing electric motor mounted directly on the suspended polisher frame. The operator stood on a wooden platform and could move the polisher to reach either of two workstations. He could polish the sides and top of one die while a second was being set in place.



The suspended polisher worked on a wide variety of shapes such as oval tops, straight tops, serpentine tops, and convex ends. An increasingly fine grit silicon carbide was used, ending with a 600-grit powder. Periodically, the polisher wiped the stone clean and put on a little water to see if all the lines were gone. If so, then the next finer grit was used. A buffer wheel was used with tin oxide and water for the final polish. Abrasive was sprinkled on the stone by hand from a group of surrounding cans – each with a different grit. The polisher was on his feet all day long since the polishing head had to be continuously moved – typically in a spiral motion, often reversing direction. The best polishers could polish three tops a day. Most could complete only two a day.

A portable tripod-mounted polisher was patented by Ercole Cavicchi of Quincy, Mass., and Barre in 1909. The polishing wheel was mounted at the end of an arm that could move in and out on rollers. The arm rotated around its point of attachment at the top of the tripod stand so the polishing wheel would reach any point on a horizontal plane. An electric motor powered the polishing wheel through gears and a sliding splined shaft. In another popular design, patented by William G. Cumming of Barre in 1937, the polishing wheel was located at one end of a centrally-supported beam and was belt driven by a counterbalancing electric motor at the other end of the beam. The motor had two speeds that allowed both grinding and polishing. Although, the beam was "rigidly" suspended (i.e., not by cable) from a crane-like boom, there were enough degrees of freedom in movement of the beam and polishing wheel that curved or slanted surfaces could be polished. A second smaller motor raised and lowered the boom.



The lathe for polishing columns, introduced in the late 1800s, was similar to the cutting lathe except it did not use a tool carriage with a cutting disc. The head stock was belt-driven by a cone of step pulleys allowing for variable turning speed. Polishing was done at a surface speed of 230 to 240 surface feet per minute so the larger the column diameter the less the rotations per minute. Initial grinding was performed by a series of four-inch wide cast iron grinding blocks that rested tightly spaced on top of the turning column. The blocks came in contact with about one-quarter of the column circumference and were curved according to the desired curvature of the finished column. The blocks were pushed by the column's rotation against a plank behind the lathe and were thus held in position. First sand and then emery was shoveled up over the grinding blocks by the operator from an abrasive trough under the lathe. The blocks were occasionally moved sideward to prevent ridges from forming between the blocks.



When the grinding was completed, eight-inch wide cast iron polishing blocks with felt covered undersides (each weighed about 100 lbs. for a 40-inch diameter column) were substituted for the grinding blocks and tin oxide was used as an abrasive. It required a total of from 40 to 50 hours to polish a column to a mirror-like surface. The Woodbury Granite Co. of Hardwick operated a polishing lathe that could accommodate a stone 25-feet long and 60-inches in diameter. By the mid 1900s, the grinding and polishing blocks had been replaced by a single long steel plane held against the turning column with a succession of increasingly fine abrasives. Other turned work – spheres, urns, vases, and balusters – was polished using one or several steel planes, each with a polishing edge pattern in the shape of the desired curvature.



There have been a remarkable number of Vermont manufacturers of granite polishing equipment, including Smith, Whitcomb & Cook, Willis A. Lane, Whitcomb Brothers, Granite City Tool Co., Cary Engineering & Machine Co., and Rouleau Granite Co. in Barre; Lane Manufacturing Co, Medad Wright & Son, and Cooley Manufacturing Co. in Montpelier; Cooley-Wright Manufacturing Co. in Waterbury; Fred R. Patch Manufacturing Co., Patch-Wegner Co., and Lincoln Iron Works in Rutland; and O. V. Hooker & Son in St. Johnsbury. Although most Barre granite manufacturers owned polishing equipment and did their own polishing, Barre had a number of specialty polishing mills that did polishing work for other granite companies that did not want to do their own polishing.



It is interesting that modern automatic polishers have adopted some of the design elements of the early line polishers with stone moved on carriages under multiple polishing heads. The French-made Thibaut 12-head continuous polisher is a typical example of a modern multi-head machine – each polishing head contained diamond abrasive blocks of various grits. The granite is moved under computer control from one polishing stage to the next and 200 square feet of granite can be polished per hour. Another automated granite-working machine, the Thibaut T858 5-Axis Computer-Numerically-Controlled Machining Center polishes, mills, edge shapes, edge polishes, drills, grooves, engraves, and cuts.