Transactions . r-. Fig. 1 and 2.—Simplest Form of Plugger Drill. These stone tools are designed to meet the usual requirements in stonedressing. The several sizes cover a variety of work, from the heaviestcutting to the most delicate tracing. The tool is valveless, hence there isbut one moving part and that a hardened piece of steel. Figs. 1 and 2 are a photograph and a sectional view of the simplestform of plugger drill. Fig. 3 shows the machine in use in dressing stone. Plugger drills are largely used for pop shooting, breaking up boulders,trimming walls, and for all light work requi
Transactions . r-. Fig. 1 and 2.—Simplest Form of Plugger Drill. These stone tools are designed to meet the usual requirements in stonedressing. The several sizes cover a variety of work, from the heaviestcutting to the most delicate tracing. The tool is valveless, hence there isbut one moving part and that a hardened piece of steel. Figs. 1 and 2 are a photograph and a sectional view of the simplestform of plugger drill. Fig. 3 shows the machine in use in dressing stone. Plugger drills are largely used for pop shooting, breaking up boulders,trimming walls, and for all light work requiring holes not exceeding 5 depth. Solid or hollow steel may be used. In the latter case the exhaustair is discharged at the bottom of the hole for the purpose of removingthe cuttings. This type of machine is equipped with a simple device for 158 ROCK-DRILLING ECONOMICS. cleaning the holes of rock cuttings which may not have been dischargedby the normal process of exhausting in the hole. This device consists
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
