US2838652A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for spark machining
Assignee: Firth Sterling Inc
•
Filing: 1955-08-30
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Granted: 1958-06-10
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Expires: 1975-08-30
Abstract
No abstract record available.
Inventors
- 👤 Cecil P Porterfield
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:43
CPC Classifications
B; B23; B23H; B23H1/00
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US1751668A
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FR854224A
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GB637793A
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US2526423A
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US2654821A
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FR1024353A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1961-06-09 | 1961-12-09 | 1962-06-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1965-06-09 | 1965-12-09 | 1966-06-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1969-06-09 | 1969-12-09 | 1970-06-10 | $7700.00 | Window Closed / Lapsed |