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US2987609A
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US
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Spark machining apparatus
Assignee: Firth Sterling Inc
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Filing: 1957-03-11
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Granted: 1961-06-06
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Expires: 1977-03-11
Abstract
No abstract record available.
Inventors
- 👤 Everard M Williams
- 👤 Porterfield Cecil Paul
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 17:48
CPC Classifications
B; B23; B23H; B23H1/00
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
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US2568464A
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US2346975A
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US2508115A
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US2835784A
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US2835785A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1964-06-05 | 1964-12-05 | 1965-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1968-06-05 | 1968-12-05 | 1969-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1972-06-05 | 1972-12-05 | 1973-06-06 | $7700.00 | Window Closed / Lapsed |