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).
Difficulties of machining a lighting dynamo commutator.
| Identifier | ExFiles\Box 50\5\ Scan238 | |
| Date | 13th October 1923 | |
| X4333 To EY. from WS. c. EFC. c. Mr. Coverley. (struck through) c. Mr. Brock. WS1/P13.10.23. X.4333 RE LIGHTING DYNAMO COMMUTATOR. The stepping down of the mica between the Commutator bars presents difficulties to machining this operation which are not easily overcome. The Commutator being built up and the machine index being constant, the milled cuts will not match up with the mica divisions. There is also a certain amount of distortion or birdcaging of the bars and it is impossible to follow the groove without cutting into the copper at one end of the slots, and even if the milled cut were wider than the mica division it would only serve to magnify the appearance of this distortion. These difficulties are inherent on any built up unit. I am confident that Mr. Coverley's and Mr. Brock's method of making this step are equally efficient and the only way to do the job successfully. To ensure that no mica adheres to the walls of the slot I have suggested to Mr. Brock that he should rigidly inspect this operation with a magnifying reading glass. WS. [Signature] | ||