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).
Comparing the machining and material considerations of hexagon versus square bolt heads.
| Identifier | ExFiles\Box 148\5\ scan0178 | |
| Date | 12th July 1937 | |
| 1260 RHC.{R. H. Coverley - Production Engineer} Cr.{Mr Cra???ster / Mr Chichester} No. By.{R.W. Bailey - Chief Engineer} Ty. Pn.{Mr Northey} HPC. Da.{Bernard Day - Chassis Design} F/MS. E.5/HP.12.7.37. Hexagon compared with Square Bold Heads. Replying to your memo RHC.{R. H. Coverley - Production Engineer}6/MJ.7.7.37, I understand that the Rate Fixing department are not in agreement that the machine speed and feed can be greater with hexagon bar. As this job is carried out, apparently only the necking down tools are subject to the direct attack of the corners of the section, and the operation of turning the stem is quite smooth. With regard to the question of the collets, I understand that the square bar collets would still be necessary for other jobs. With regard to the hexagon sizes, these have to be larger than given in RHC.{R. H. Coverley - Production Engineer}6/MJ.7.7.37 to correspond with the table of standard hexagons, and also to correspond with the sizes of hexagons we use for the nuts. The feet per ton for the hexagon bar would, therefore, be rather less than shown in your memo. The complete cost figures for material which have been given to me can be seen on copy of C/Rb.{R. Bowen}E/W.9.7.37 attached. E.{Mr Elliott - Chief Engineer} ATT: | ||