Patent US2521791A successfully refreshed from Google Patents.
US2521791A
Expired / Lapsed
US
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Replaceable blade bit
Assignee: Individual
•
Filing: 1945-09-21
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Granted: 1950-09-12
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Expires: 1965-09-21
Abstract
No abstract record available.
Inventors
- 👤 George G Harrington
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 21:48
CPC Classifications
E; E21; E21B; E21B10/00; E21B10/62
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US1388490A
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US1845168A
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US1858988A
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US1901643A
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US1902885A
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US2132493A
Cited
US2190434A
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US2246812A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1953-09-11 | 1954-03-13 | 1954-09-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1957-09-11 | 1958-03-13 | 1958-09-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1961-09-11 | 1962-03-13 | 1962-09-12 | $7700.00 | Window Closed / Lapsed |