Issued Patents All Time
Showing 26–29 of 29 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4862977 | Drill bit and cutter therefor | John D. Barr, Terry R. Matthias | 1989-09-05 |
| 4733735 | Rotary drill bits | John D. Barr, John M. Fuller | 1988-03-29 |
| 4697654 | Rotary drill bits | John D. Barr | 1987-10-06 |
| 4669556 | Drill bit and cutter therefor | John D. Barr, Terry R. Matthias | 1987-06-02 |