From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Blueprint detailing a modification to an existing piece by adding a countersink.
| Identifier | ExFiles\Box 56\3\ Scan117 | |
| Date | 29th November 1928 guessed | |
| .250 60° E74044 COUNTERSINK EXISTING PIECE AT 60° | ||