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 doming of platinum and tungsten battery ignition contact screw points.
| Identifier | ExFiles\Box 35\6\ scan 287 | |
| Date | 21th June 1927 | |
| 1 X2894 21.6.27. X.4652. X.2894. [crossed out] X.919 DOMING OF PLATINUM AND TUNGSTEN BATTERY IGNITION CONTACT SCREW POINTS. The following figures have been finally fixed :- Dia. of std. platinum point = .150" Dia. of tungsten " = .175" Dia. of doming for platinum screw point = 5.625°, or radius 2.812" Dia. of doming for tungsten screw point = 7.650° or radius 3.825. These correspond in each case to a height of doming of the centre of the surface of the point above the circumference of .001". The D.{John DeLooze - Company Secretary} Numbers are as follows :- For tungsten:- D.51407 - Screw Point with .001" doming. D.51408 - Lever points - flat. D.51560 SCREW POINT - FLAT. For platinum:- D.50467 - Lever Point - flat. ('Screw' is crossed out and 'Lever' is handwritten above) D.50468 - Screw Point - flat. ('Lever' is crossed out and 'Screw' is handwritten above) D.{John DeLooze - Company Secretary} 51503 - Expl. plat. Screw Point with .001" doming. D.5 EFC. | ||