Читать книгу The Handyman's Book of Tools, Materials, and Processes Employed in Woodworking - Paul N. Hasluck - Страница 151

There appears to be great differences in the speeds at which grindstones are run, but in England the speed of the face may be taken at from 800 ft. to 1,000 ft. per minute. Taking the higher of these values, the speed of a stone 1 ft. in diameter will be revolutions per minute. The speed of a grindstone is calculated by the number of feet per minute which the periphery travels. To find the rate of speed at the periphery, multiply the diameter in inches by 3·1416 and divide by 12, then multiply by the number of revolutions, the product being the number of feet per minute which the stone is travelling. Example: A stone 24 in. in diameter, making 159 revolutions per minute, has a speed of 999 ft. (roughly 1,000 ft.) per minute

The makers of Ohio and Huron grindstones state that the former should run at about 2,500 ft. per minute, and the latter somewhat higher.

Fig. 436.—Treadle Grindstone on Wooden Stand.