US Patent: 1,881,535 - Rock drill bit


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US Patent: 1,881,535

Drill
Rock drill bit

Patentee:

John M. Hargrave (exact or similar names) - Cincinnati, OH

USPTO Classifications:

175/420, 76/108.2

Tool Categories:

metalworking machines : drilling and boring : drill bits

woodworking tools : hand drills : drill bits

Assignees:

None

Manufacturer:

Cincinnati Tool Co. - Cincinnati, OH

Witnesses:

Unknown

Patent Dates:
Applied:	Nov. 23, 1931
Granted:	Oct. 11, 1932

Patent Pictures:

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Description:

Inventor Hargrave was the president of Cincinnati Tool Co.

"...a rock drill having an improved arrangement of cutting edges accomplishing a more rapid drilling operation, drilling an extremely regular and smooth walled hole and in which the sharpness of the cutting edges is preserved over an extremely long period of time. It is a further object of this invention to provide an improved drill in which the cutting edges may be sharpened by a simple grinding operation presenting a minimum number of edges for sharpening and having the edges arranged for sharpening by a conventional device such as a standard grinding wheel."