Granted Patent
Utility
US 4,777,850 · App. 07/104,656
Drill-out threaded broken bolt extractor
Inventor:
Eli Polonsky
Patented Case
View Patent ↗
Granted: Oct 18, 1988
Filed: Oct 5, 1987
Inventor
Eli Polonsky
Assignee (at issue)
Drill-Out, Inc.
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.