US Patent: 413,316
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Attachment for Augers
Counterbore Auger Attachment
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Patentee:
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| William J. M. Dobson (exact or similar names) - Brooklyn, NY |
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Patent Dates:
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| Applied: |
Mar. 12, 1889 |
| Granted: |
Oct. 22, 1889 |
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Jeff Joslin (dm)
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Description: |
| Metallic block to serve as a "pilot" for counterboring existing holes to any depth. To be provided in varying diameters to match standard bit sizes, and threaded to match lead screws - or supplied with soft metal centers to allow bit lead screws to safely self-tap.
The 1897 Strelinger catalogue offers them in solid brass, except for soft metal centers, in sets of 12 sizes. |
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