Granted Patent
Utility
US 4,558,753 · App. 06/468,669
Drag bit and cutters
Inventor:
John D. Barr
Patented Case
View Patent ↗
Granted: Dec 17, 1985
Filed: Feb 22, 1983
Inventor
John D. Barr
Assignee (at issue)
NL Industries, 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.