Rolls-Royce Archives
         « Prev  Box Series  Next »        

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).
Technical memorandum discussing manufacturing variations and machining allowances for a spanner.

Identifier  ExFiles\Box 20\8\  Scan040
Date  14th June 1923
  
SY12-P14.6.23. contd. - 2 -

Referring to these columns you will notice that as pointed out above, the handle thicknesses are close to drawing size, but jaw thicknesses vary from the LeC. drawing more than the handle thicknesses, but not anything like the extent shewn on E2/M12623, The maximum variation of the metal in the head of the spanner is .045", but since the thickness of the head was a comparatively small issue we permitted wide limits on this factor, providing it cleaned up.

The fault is not so much in the quantity of metal used in the die initially as in the allowance for machining, which should have been only sufficient for glazing or surface grinding, whereas the drop forgers have gone beyond our forging drawing size slightly, with the result that when the Works glaze up the spanner head, from the point of view of getting a clean finish only they left more metal on this than they should have done by the drawing dimensioning and limit. As a matter of fact, we had actually just removed all machining allowances entirely from the head of the spanner, leaving it drawing size only, as we considered the Operation Department had made a mistake in allowing even .030" which was their allowance overall for grinding, as the flash will cover the allowance quite easily.

If still in view of the corrections we draw your attention to R.{Sir Henry Royce} considers that it is necessary to machine
contd.
  
  


Copyright Sustain 2025, All Rights Reserved.    whatever is rightly done, however humble, is noble
An unhandled error has occurred. Reload 🗙