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).
Comparison memo on the manufacturing and material advantages of using hexagon bar over square bar for bolt heads.
| Identifier | ExFiles\Box 148\5\ scan0176 | |
| Date | 7th July 1937 | |
| To E.{Mr Elliott - Chief Engineer} & Hs.{Lord Ernest Hives - Chair} From HIC. 1260. c. to BY.{R.W. Bailey - Chief Engineer} & Hy.{Tom Haldenby - Plant Engineer} c. to Rm.{William Robotham - Chief Engineer} c. to HFS. c. to Da.{Bernard Day - Chassis Design} c. to E/NS.{Norman Scott} HEXAGON COMPARED WITH SQUARE BOLT HEADS. Hs.{Lord Ernest Hives - Chair} has passed to me your memo E.5/HP.2.7.37. It may be true that the Hexagon headed bolt is doubtful regarding shoulder location to prevent turning when used in Aluminium but there are advantages in manufacture and material economies which outweigh the disadvantage referred to. The Manufacturing advantages are (a) With the Hexagon bar the machine speed and feed is greater because the intermittent cut is not so pronounced as in the case of Square bar. (b) Turning tools last longer and maintenance costs are lower with the use of Hexagon because the corners of Square bar break down the cutting edge of the tools quicker. (c) The adoption of Hexagon bar would prove to be an economy on collets as now it is necessary to carry square collets in addition to Hexagon which the machines are equipped with for the production of Hexagon nuts. (d) The fact of standardising Hexagon reduces setting times because the use of Square bar means additional setting in the changeover for this type of material which is a distinct advantage from a machining point of view. Further advantages are on material economies because the feetage, or length per ton, is greater in the case of the Hexagon, examples as follow - 5/8" Hexagon 4.2 lbs. per 10 ft. = 5,333 ft. per ton. 5/8" Square 4.78 lbs. per 10 ft. = 4,686 ft. per ton. Increased length of Hexagon compared with Square bar ...... 647 ft. per ton. | ||