{snip}
I have any number of drawings dating back to at least 1937 which show that Rolls-Royce were working to tolerances just as tight as we do nowadays.

Pete

That is the bit I’m arguing about. Tight tolerances can be a knee jerk reaction to problems – sometimes caused by how the parts are dimensioned and inspected. Good engineering design is about achieving the loosest tolerances possible – it’s cheaper as it produces less scrap

Richard

That’s an irrelevant objection. {snip}

Is it though? Rolt had a background in small teams erecting steam engines at Kerr Stuart. He was disillusioned with this as he prized the craft of engineering. He entered RR expecting to be able to use that craft even more and (inexplicably to me) got put on a drilling/tapping machine on a production line.

He must have been the sharpest of square pegs in a very tight round hole

None of which leads us any nearer to how the parts were dimensioned or inspected – which is where scrap is made

Richard

I’ve provided a first hand account by an experienced engineer

{snip}

But it’s been ignored completely. :rolleyes:

The problem with that quote for me is that Tom Rolt is hardly an unbiased observer. IIRC Tom was delighted by the hand made (and very non-interchangeable) nuts and bolts on the chassis of Dolgoch (see Railway Adventure), so as he said, he expected to be hand fettling individual engines rather than working on a production line. This would match his experience of his apprenticeship in Kerr Stuart. Doesn’t tell us anything about the manufacturing drawings unfortunately

Richard

Marching always goes better with a band

Richard

{snip}

I could see how Ford would want to re-draw the Rolls-Royce drawings but if Ford could produce parts to tighter tolerances then Ford wouldn’t need to re-redraw anything; Ford parts would still have been within Rolls-Royces (looser, but acceptable) tolerances.

{snip}

What if by careful examination of the tolerancing, perhaps by using more appropriate datums for metrology and jigging, Ford could produce materiel to looser tolerances that was still interchangeable? In cost-down exercises I have been involved in, this is often how this was achieved

Richard

Nope, I don’t buy that! 🙂

I think I’m right in saying that Roll-Royce ‘mass produced’ more engines than Ford and Packard put together during the war.

Certainly tolerances weren’t ‘figured out on the shop floor’ and nor was an engine ever ‘built’ by a single individual; while the final assembly of the components may have been down to one individual those components would have been machined by possibly hundreds of other workers and in the majority of cases the individual fitting them couldn’t influence the final performance of the engine (unless he or she mucked it up in some way).

It should be possible to confirm the tolerance/ fit and finish stuff if the drawings are still around. Honestly, I wouldn’t be surprised to find some of those famous instructions on early drawings like “a good push fit”*

Again, without evidence, I would expect the expertise that Ford brought would be to do with production methods – jig and fixture design, process planning, holding methods, combining machining operations, use of appropriate machines. This would almost inevitably result in greater repeatability and similarity between components

Would that show up on the test bed? No idea. Would it result in more engines per week? Oh yes.

Richard

*Looking the other way, as an ex-Lucas Aerospace apprentice, the first Ford drawing (a cylinder head) I ever saw filled me with horror. Casting drawing, machining drawing, assembly drawing, inspection drawing – yep, it was all of those in one drawing 😮

They look extremely *tall* for Merlin pistons :confused:

Perhaps they are:

a/. not finished

b/. not Merlin pistons

😮

Richard