yulzari
Staff Sergeant
What Rolls Royce provided to Ford France was direct copies of their drawings etc. for what they were making at the time. Those drawings were for a small skilled workforce making a few hundred engines which was all that Rolls Royce had been expecting to make. Hence tolerances and hand fitting suited to such a small run production.
When they went to shadow factory mass production they adjusted them to fixed standards to suit semi skilled machine work and this is what Ford of Britain had supplied to them and those would have been updated to Ford France had that project gone ahead.
Also Merlin factories in Britain had to use existing machinery with only a limited amount of new machines, given the competition for machines in a country on a war economy. Similar competition delayed welding tank hulls as trained and experienced welders were poached by the ship building industry which had an equal, if not higher in some cases, labour priority. Packard had access, albeit in competition with other aero engine manufacturers, to new latest machinery so could achieve, and indeed needed, finer tolerances than British Merlins which achieved similar tolerances by other means such as selecting matching pistons to an engine from piston stocks rather than having all pistons and cylinders made to a necessary tolerance.
It was not a matter of master craftsmen at Rolls Royce filing engine parts from a set of forging by hand like magic gnomes nor futuristic Americans popping out identical parts from a time travelled replicator but a sensible use of available resources at each factory. The end result was Merlin engines which were interchangeable across the factories and across the Atlantic Ocean.
When they went to shadow factory mass production they adjusted them to fixed standards to suit semi skilled machine work and this is what Ford of Britain had supplied to them and those would have been updated to Ford France had that project gone ahead.
Also Merlin factories in Britain had to use existing machinery with only a limited amount of new machines, given the competition for machines in a country on a war economy. Similar competition delayed welding tank hulls as trained and experienced welders were poached by the ship building industry which had an equal, if not higher in some cases, labour priority. Packard had access, albeit in competition with other aero engine manufacturers, to new latest machinery so could achieve, and indeed needed, finer tolerances than British Merlins which achieved similar tolerances by other means such as selecting matching pistons to an engine from piston stocks rather than having all pistons and cylinders made to a necessary tolerance.
It was not a matter of master craftsmen at Rolls Royce filing engine parts from a set of forging by hand like magic gnomes nor futuristic Americans popping out identical parts from a time travelled replicator but a sensible use of available resources at each factory. The end result was Merlin engines which were interchangeable across the factories and across the Atlantic Ocean.
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