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).
With diagrams detailing the manufacturing process and material considerations for a Bakelite rim component.
| Identifier | ExFiles\Box 39\3\ Scan093 | |
| Date | 24th May 1921 guessed | |
| -4- Also it may be necessary to cut the rim between arms thus:- FINE SAW CUT. The split is forced together by the pressure in the dies and forms a sliding joint to take care of changes of weather, which might crack the covering of a rim molded solid, due to difference in co-efficients of expansion that of the Bakelite being very small indeed. The contraction of Bakelite-wood-powder, composition (the standard molding material) in the dies is about .004 per inch, and since the temperature of molding is about 350°F.{Mr Friese} the contraction of the aluminium is about the same. It is later on due to climatic changes that trouble is to be feared. A further refinement suggested is the use of "preform dies" - namely, soft steel dies which would rough mold the plastic sheet, cold, to a form for the top and bottom halves of the rim. These plastic strips would then be held in the final dies, and filled with a fibrous material such as cotton wick, impregnated with un-cured Bakelite varnish, thus:- The preforms would be "full" enough in section to allow enough compress-ion so that everything was squeezed tight when the dies were down. UPPER & LOWER PREFORMS (Imperfect copy) Such a construction would have great tensile strength and would be free from cracking due to climatic changes. This is the way the Bakelite-canvas aeroplane propellers are being made. A letter on more general information follows. Yours truly, ROLLS - ROYCE OF AMERICA, Inc. Per (Sgd.) M.Olley. MO/G.{Mr Griffiths - Chief Accountant / Mr Gnapp} CC.Messrs Belnap Beaver Manning Nadin Southern BagnallCaswell Hulley | ||