Standard and tentative methods of sampling and testing highway materials : recommended by the Second Conference of State Highway Testing Engineers and Chemists, Washington, , Feb 23-27, 1920 . eigh in the neighborhood of carat each and from six to eight diamondsare required for a 1-inch drill. They may be obtained from any of the diamondimporters. The diamond drill consists of a bronze crown soldered to the end of a seamless steeltube about 4§ inches long and 1| inches outside diameter and carrying six diamonds,each about ^ inch in diameter. The other end of the steel tube carries a Xo
Standard and tentative methods of sampling and testing highway materials : recommended by the Second Conference of State Highway Testing Engineers and Chemists, Washington, , Feb 23-27, 1920 . eigh in the neighborhood of carat each and from six to eight diamondsare required for a 1-inch drill. They may be obtained from any of the diamondimporters. The diamond drill consists of a bronze crown soldered to the end of a seamless steeltube about 4§ inches long and 1| inches outside diameter and carrying six diamonds,each about ^ inch in diameter. The other end of the steel tube carries a Xo. 2 Morsetaper hollow drill shank through which water is admitted to the inside of the drill crown proper is made of Tobin bronze. 1-inch internal diameter. T^-inchexternal diameter. | inch high, with a recess tj inch in depth by If inches in diameterin which the steel tube is soldered. Figure 3 gives a detailed new of the drill crownshowing the various dimensions. Tn figure 36 are shown the various pieces of appara-tus used in the operation of setting the diamonds in the drill crown. A is a piece ofcold-drawn steel 11 by J by 6 inches with a yoke 0 and thumbscrew and is used to. Fig. 36.—Apparatus used in manufacture of diamond drill. hold the drill crowns. After mounting a crown in the clamp as shown, six holes aredrilled in the face of the crown at equal distances apart, three of the holes almostbreaking through the outside of the face of the ring and three almost breaking throughthe inside of the face. The holes should be slightly smaller than the diamonds whichare to be used, and each should be slightly nicked on the thin edge with a fine diamond is now placed in one of the holes, gently tapped with a piece ot brass soas to hold it in place, after which the crown is placed in a small jewelers nee D having jaws of soft steel or brass and with which the diamond is forced into the the diamond not stand the pressure and crumble, it is not fit fo
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectroadmat, bookyear1921
