American Blacksmithing, toolsmiths' and steelworkers' manual . xception that the bit on a drill for limestone is drawnout much thinner and to a sharp cutting edge, thecutting edge being made slightly rounding. Ball drills are made by taking a bar of iron about5 feet long and II/4 inches in diameter, then welding apiece of % octagon cast steel at each end, afterwards 134 THE TWENTIETH CENTURY drawing out as a hand drill, thus having a drill ateach end. But bear in mind that the drill on one endshould be %, the other %. A ball drill is used fordrilling by raising it up, then allowing it to dropd
American Blacksmithing, toolsmiths' and steelworkers' manual . xception that the bit on a drill for limestone is drawnout much thinner and to a sharp cutting edge, thecutting edge being made slightly rounding. Ball drills are made by taking a bar of iron about5 feet long and II/4 inches in diameter, then welding apiece of % octagon cast steel at each end, afterwards 134 THE TWENTIETH CENTURY drawing out as a hand drill, thus having a drill ateach end. But bear in mind that the drill on one endshould be %, the other %. A ball drill is used fordrilling by raising it up, then allowing it to dropdown from a vertical position, the larger drill on oneend being to start the hole, and the smaller one at theopposite end being used to finish. Thus the large drillgives clearance to the smaller drill, which prevents itfrom sticking in the hole. After hardening, draw thetemper to a pale blue. The Tooth Axe. The tooth axe is a tool used a great deal by lime-stone cutters, and which has the cutting teeth at eachend as illustrated in Fig. 74. To make a tooth axe.
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