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US Patent: 2,507,231
Screw Driver Having Cruciform Bit
Joseph J. Tomalis, estate of (deceased) - Providence, RI
Lillian Dolores Tomalis, administratrix - Providence, RI

USPTO Classifications:

Tool Categories:
screwdrivers : screwdriver blades

American Screw Co. - Providence, RI

Vaco Products Co. - Chicago, IL
Irwin Industrial Tool Co. - Wilmington, OH

none listed

Patent Dates:
Applied: Oct. 29, 1947
Granted: May 09, 1950

Patent Pictures: [ 1 | 2 ]
USPTO pdf tiff
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"Vintage Machinery" entry for American Screw Co.
Watson, Cole, Grindle & Watson - patent attorneys

Original application 30 Dec, 1942. Divided and this application 29 Oct, 1947.

This patent pertains to the shape of the Phillips style driver to allow for more torque on the screw with less cam out force. (See also patent no. 2,046,838 for earlier Phillips screwdriver patent).

The markings on related screwdrivers hint at a "manufactured under license" arrangement. The piece in the 2nd image is one example.

The full marking on the shank is VACO Made U.S.A. //CHROME VANADIUM STEEL // PHILLIPS POINT No.3 // Pat. No. 2507231 Lic. No. 9

A 2nd known example is marked: IRWIN 3000-3" Made in U.S. of A. (on handle) / Phillips//Lic. 7-Pat//2507231//Made in U.S.A.//No. 1 point//Carbon// (on shank)

A 3rd known example with wood handle is marked on the shank: PHILLIPS - LIC. 40 / PAT. 2507231 / CHROME VANADIUM / No. 3 PT - U.S.A. /

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