..Report on the building and ornamental stones of Canada, volI-V . 89 until sufficiently reduced. The finish produced by the rubbing bed issufficient for outside work in marble and is known as the sand Fig. 4. Overhead rubbing bed. Gritting and Polishing Machines. For further smoothing, the stone is taken from the rubbing beds to thegritting machines and thence to the polishers. Whether for granite or formarble the construction of all these machines is much alike, but the weightand rigidity vary with the class of work. Marble gritters and polishers differin the character of the abrasi
..Report on the building and ornamental stones of Canada, volI-V . 89 until sufficiently reduced. The finish produced by the rubbing bed issufficient for outside work in marble and is known as the sand Fig. 4. Overhead rubbing bed. Gritting and Polishing Machines. For further smoothing, the stone is taken from the rubbing beds to thegritting machines and thence to the polishers. Whether for granite or formarble the construction of all these machines is much alike, but the weightand rigidity vary with the class of work. Marble gritters and polishers differin the character of the abrasives used and the speed of rotation. For granitethe head or actual polishing surface is quite different. The machine (Plate XVIII), consists of a horizontally rotating discto which different types of head may be attached. The upiight spindle of thedisc rotates in bearings at the end of a jointed and adjustable arm so thatthe polishing surface may be moved over all parts of the underlying marble gritting the heads are about 12 inches in diameter, with lilocksof abrasives arranged in a radial manner with interspaces between. Theabrasives most generally used are Ijricks of carborundum, of which fi
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbuildin, bookyear1912
