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943,009
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Dec. 14, 1909
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Tapping and drilling tool
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John H. Dorman |
New York, NY |
These tapping heads were manufactured for decades. The firm name had become John H. Dorman & Son by 1919, then Dorman Machine Tool Works by about 1948, and by the late '50s the Dorman tapper was being manufactured by Thriftmaster Products Corp. of Lancaster, PA.
"In a tapping attachment for drill presses, the combination with a casting containing driving and reversing gears and provided with means for holding it against rotation, of a chuck-spindle having a longitudinal recess, a pivotal retaining pin therein, a transverse clutch-bar loosely held held by the pin in said spindle recess, retaining shoulders on said bar, and oppositely projecting pins upon the driving and reverse gears adapted to be alternately engaged by the bar..." |