DescriptionUS patent 161390 Allan Cummings 1875 wood screw drives.png
English: US patent 161390, Allan Cummings, 1875, wood screw drives. Probably not many screws were manufactured on this design before the patent expired. Not until 1908, when P.L. Robertson of Canada had finished developing his efficient cold-forming methods, did the internal-wrenching square drive become commonly used.
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US patent 161390, Allan Cummings, 1875, wood screw drives[1], (Please provide a date or year)
Author
Allan Cummings
Licensing
Public domainPublic domainfalsefalse
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