Patent US2979639A successfully refreshed from Google Patents.
US2979639A
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Pilot pulse spark machining methods and apparatus
Assignee: Firth Sterling Inc
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Filing: 1958-06-09
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Granted: 1961-04-11
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Expires: 1978-06-09
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 08:33
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/32; H01J37/34; B; B23; B23H; B23H1/00; B23H1/02; B23H1/022
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2186013A
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US2478907A
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US2294498A
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US2363332A
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US2589720A
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US2804575A
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US2856565A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1964-04-10 | 1964-10-10 | 1965-04-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1968-04-10 | 1968-10-10 | 1969-04-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1972-04-10 | 1972-10-10 | 1973-04-11 | $7700.00 | Window Closed / Lapsed |