lat-pointed drill, and has a shoulder on its stem thatstops the progress of the drill when it has gone throughthe first part of the pinion head and nearly through the THE MODERN CLOCK. 251 other. All operators make their own drills and the limitsof error are for pitch diameter .0005 inch; error of… … Fig. 80. Pinion Drilling Machine. position in the machine, and by pulling a lever, the drill,which is running at a speed of about 22,000 revolutions aminute, comes in contact with the brass heads of the pinionand bores the one through and the other nearly through.The lever is then let go, and a…
Clocks and watches
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