| Year | 1939 |
| Date | 02-Mar |
| Volume | 80 |
| Issue | 1,973 |
| Page | 257 |
| Category | In The Workshop |
| Part | |
| Title | Drill Grinding |
| Author | |
| Notes | An Ingenious Automatic Grinder embodying new working principles. The "Black Diamond" precision drill grinider, operation of locating device, action of grinding fixture, wheel dressing device, reducing thickness of drill webs |