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).
Tolerances of secondary wire for ignition coils from various suppliers.
| Identifier | ExFiles\Box 69\1\ scan0262 | |
| Date | 27th November 1929 | |
| EFC. X8710. BY/RD10/DM.{D. Munro}27.11.29. Sizes of Secondary Wire. In view of the recent criticism of the closeness of the secondary winding on the ignition coil, we have been in communication with the following makers of wire and each one demands .0005 tolerance. Connollys. Mc.Leod & Mc.Leod. London Electric. British Insulated. Concordia. One or two makers offered us a little tighter tolerance but each one demanded higher charges. The saving gained in the closer tolerance was only .0001 and we do not consider that is a practical proposition. From the foregoing you will see that we are bound to allow for variations in wire size and that even Watfords who purchase wire from Mc.Leod & Mc.Leod have this to cope with, and the wire which McLeods supply is made abroad, a source of supply which we should hesitate to go to. We think, therefore, that we are doing the best we possibly can under practical conditions. BY/RD. | ||