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).
Proposal of 'stepping' Main Journal sizes for boring operations versus the existing 'Peregrine' scheme.
| Identifier | ExFiles\Box 6\6\ 06-page013 | |
| Date | 12th May 1936 | |
| To from Eft. By Day Work Hs.{Lord Ernest Hives - Chair} Dgn [Handwritten signatures: R Wood, RHS, Seen] [Handwritten reference and date]: BP62/BH.12.5.36. [Handwritten notes over the first paragraph]: Proposals on High Speed boring has removed the necessity of stepping sizes SUBMITTED & were adopted at one time when varying Ops were performed with equipment originally intended for single Op No BP50/BH/EP.{G. Eric Platford - Chief Quality Engineer}35.4 re-dated 7.5.34. [Typed text]: re-dated 7.5.34. With reference to the suggestion of stepping Main Journal sizes, this proposal does not appear attractive for our limited production. We have new schemes now in progress intended to improve our boring operation of Crankcases, which, together with the adoption of a scheme originally developed for the Peregrine, should bring about an appreciable saving on this operation. The Peregrine scheme of boring is essentially one in which all the cutters are arranged to cut to size, and remain fixed in boring bars, the Crankcase being secured to a jig which is independent of the boring bar guide bushes, and is arranged to be moved across the line of centres, an amount sufficient to allow the bar and cutters to be moved along the rough casting. Slots in the boring bar guide bushes further facilitates the bar passing into position ready for the short length of cut. The crankcase is then moved back to its correct position for boring. Stepping sizes would not help or improve on this method of boring. In the case of the final size reaming of the white-metal bearings assembled in the Crankcase, stepping of sizes would show a small saving on this relatively short operation, but this would definitely be offset by having to produce and care for bearing bushes of various external diameters and by the considerable increase in the manufacture of the Crankshaft. In large production shops dealing with tens of thousands of bearings, a number of machines are arranged to cope with the required output, each machine remaining set up to do its own individual size of Bearing. With our smaller production multiplication of sizes would increase the cost of manufacture, more set-ups would be necessary, and the quantities per set-up would be less, besides requiring the necessary number of extra fixtures, tools, arbors, and gauges for turning, boring, grinding, drilling etc. | ||