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).
Specifications for building two dynamos using parts from a starter motor.
| Identifier | ExFiles\Box 68\4\ scan0203 | |
| Date | 22th March 1920 | |
| X.1640 To Ck.{Mr Clark} from R.{Sir Henry Royce} c. to CJ. X.294. c. to Bn.{W.O. Bentley / Mr Barrington} X.3526. RE DYNAMOS. X.1640. R6/G22.3.20. Referring to your visit here last week you will remember that we came to the conclusion that it was worth while building two dynamos from the parts of the starter motor as far as they are suitable, to conform to the following particulars. The field magnet system would be taken exactly as made for starters and wound with a single shunt circuit consisting of as much wire as possible of 20's or 21's S.W.G. fine double cotton covered wound in complete coils to the biggest dimension possible, and pressed into the curved form to lie neatly against the outer and circular ring to the carcase. The armature core of plain discs would be built up with shellac and flaked mica, heated, pressed, and screwed up while at the temperature of melting shellac, and turned and ground on the outside .035" smaller than the ground bore of the pole pieces. Grooves would be milled in the armature core slightly spirally in the first instance, and the ends of the pole pieces would be eased off, also the pitch of the grooves, so as to take every precaution that the singing noise would be cured. The grooving would be narrow slots for the top and bottom half of the single coils. In one case there would be about 45 slots of .08" wide and a sufficient depth for 12 turns of wire and insulation. Contd. | ||