The cutting of glass with steel has been demonstrated to be possible provided its point is ground into the form of the common glaziers' diamond. But while hard steel of this form will cut glass, it is diflacult to bring a steel point to the required shape, and it also soon wears out and becomes worthless, until reground. Many efforts have been made to make a tool of steel that would compete at least approximately with the real diamond for this purpose. It has been discovered that a small cylindrical point of steel when made to rotate upon glass in such a manner that its longitudinal axis shall make an angle of 45 degrees with the surface of the glass, approaches in effect so nearly to that of the real diamond that it is a very cheap and effective substitute. The engraving illustrates the form of an instrument, and the mode of applying the principle enunciated to the cutting of glass. A is the end of a small cylinder, which is turned on the end of a spindle; this spindle rolls on the edges of two small disks, B, which lessens its friction enough to permit free rotation, live opposite end of the spindle has also a pointed bearing running in an adjustable center, so that the friction is very small. The following is tho mode of using this tool. The cutter is placed on the glass as shown in the engraving, care being taken to secure the proper angle of 45 degrees. It is then drawn toward the operator with a gentle pressure. Tho tool emits a peculiar singing sound as the edge cuts the glass. It is claimed for this implement that it is very durable, that it can be used with great facility, that it is not liable to get out of order or break, and that it will cut glass oven more rapidly than the diamond. We have tried its cutting properties, and can vouch for the remarkable facility with which glass can be cut by it. The cutting edge can be kept sharp by means of an ordinary whetstone, a small wooden cylinder being fixed to the spindle so that rotation can be prevented while sharpening. Curves are cut as easily as straight lines. The facility with which it. cuts has won for it the name of the magic diamond. A clock manufacturing firm doing an extensive business at Bristol, Conn., have used it for cutting circular glass plates, and pronounce it superior to the diamond for that purpose. Patented Dec. 29, 1868. For further particulars address Messrs. J, Russell Co., 83 Beekman street. New York city.
This article was originally published with the title "Cutting Glass with Steel—The Magic Diamond" in Scientific American 21, 4, 56 (July 1869)