US Patent: 120,279
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| Improvement in rock-drills
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Patentee:
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| Simon Ingersoll (exact or similar names) - New York, NY |
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Patent Dates:
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| Granted: |
Oct. 24, 1871 |
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Jeff Joslin
Vintage Machinery entry for Ingersoll-Rand Co.
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Description: |
| The invention is a rock-drilling bit with a slight helical twist that causes the bit to revolve while in use. Previous drill bits had this general form but were square in cross-section. This new bit is round in cross-section except for the relatively shallow groove, and this new shape makes a stronger bit with more cutting edges. |
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