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).
Use of metric versus inch-sized ball bearings for American productions.
| Identifier | WestWitteringFiles\H\November1921\ Scan69 | |
| Date | 9th November 1921 | |
| To [strikethrough]C.L.[/strikethrough] from R.{Sir Henry Royce} Copy to [strikethrough]HJ[/strikethrough] [strikethrough]MOR?[/strikethrough] " " [strikethrough]HB{C. E. Harcombe}[/strikethrough] " " [strikethrough]AY?[/strikethrough] [strikethrough]R.R. of America.[/strikethrough] { For attention of [strikethrough]O.Y.[/strikethrough] C.S. Halnan.) ORIGINAL RB{R. Bowen}/G23/11/21. 2 x547. RK BALL BEARINGS - U.S.A. - (CJ/PY25/D9/11/21.) X3907 Regarding the metric sized ball bearings for American productions, I did not think it was possible for Springfield to do anything at the moment. I thought they wished to convey to us the difficulties in obtaining bearings in inch dimensions, so that any new designs which may be forthcoming we should adopt metric sizes. It is manifest that with the small output, it would not be a wise policy to change the sizes of the bearings on the existing productions from the present standard to those of exact metric dimensions. You will understand that in the past there has been no reason for adopting either metric or inch sizes in preference, and it often simplifies the design to use either, owing to the fact that close to most of these ball bearings a screw thread is required which, in England, is generally in inch sizes. Under the present state the metric dimensions combined with the inch had led to still greater confusion, and the longer the muddle goes on the more expensive it will be to get rid of, but principally owing to standard screw threads we cannot possibly adopt metric dimensions entirely, unless we scrap these also. We are not prepared, especially at the moment, to recommend such a costly move, unless by order of the Government, but we have always followed the ball bearing standard lists, and shall in future only use those of metric dimensions, but considering our English standard list includes those of inch dimensions, it may be difficult to avoid these occasionally being included in a design. [Stamp: 1261 24 NOV 1921 R.{Sir Henry Royce} SH] | ||