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).
Casting patterns, shrinkage, and new equipment for experimental Bentley engine programmes.
Identifier | ExFiles\Box 146\4\ scan0006 | |
Date | 21th November 1938 | |
-2- Sft{Mr Swift}/EW1/BH.21.11.38. castings, then because we make a 20% alteration, converting into the B.80, using the original parts etc., same is not correct. Our opinion is this; if our foundry had used discretion, possibly the first casting would have been satisfactory for experimental purposes, but you cannot expect 100% production patterns for an experimental job, which is now suggested, i.e. metal barrels etc. In the first place you asked for patterns to give six sets of each, and if tests were satisfactory, production patterns would be instructed later. Referring to shrinkage of barrels we have checked same and find they are drawing size to +.025, and in any case shrinkage definitely has not taken place since the completion of 6 sets on 15.9.38, so what was satisfactory for B.60 should be good enough for B.80. Regarding your remarks of being mainly responsible for the suggestion of combined patterns - it should be realised that it is a saving of paper figures only, for it is an expense every time changing over, owing to the patterns being constructed differently from standard - it is a series of interchangeable loose pieces for both units. The correct position from the start should have been two separate patterns with one set of common coreboxes where necessary, and probably under this scheme a casting for B.80 would have been produced a month ago, instead, we are now faced with the position of not having a substantial pattern of either, without further expense. NEW PATTERN EQUIPMENT. We give herewith, the information for future experimental programme:- (1) Bentley 60, Monoblock 3½" bore. Pattern B.80 could be converted back to this model, and brought up to standard. Metal Barrels etc. Cost... £120. (2) Bentley 80, Monoblock 3¾" bore. [Handwritten '60' is written above '80'] Pattern of the above when standardised could be used. Practically a new set of Coreboxes would be necessary owing to larger bore and moving of Tappet wall. Approximate cost........................... £480. | ||