Crankshafts

[Milosh]

Rolls Royce (who examined the DB engine) cautioned the restorers of the "Black Six" not to bend the crank because they doubted very much their own ability to fabricate another one that was as "true".

Why was this?
couldn't duplicate the manufacturing tolerance specs?
couldn't duplicate the composition of the steel?
or other reasons

 

[riacrato]

Lack of tooling I would guess. Weren't ww2 crankshafts usually forged? Very expensive to recreate that tooling for a single engine and probably almost impossible to do without original specifications.

 

[Timppa]

Rolls Royce (who examined the DB engine) cautioned the restorers of the "Black Six" not to bend the crank because they doubted very much their own ability to fabricate another one that was as "true".

IMO it is just a polite way to say: "We cannot and won't do this kind of custom work at any reasonable price. Find a machining workshop elsewhere, like in Eastern Europe or in China."

 

[fastmongrel]

I would imagine Rolls Royce in 1940 could have made a crankshaft good enough to replace the DB one but in 2010 they build gas turbines and nuclear reactors they dont have the skills or machinery to work on a piston engine.

If you wanted a one off crankshaft you would ask someone who specialises in the work asking Rolls to do it would be like asking Maclaren to build a horse buggy

 

[Milosh]

Thanks guys. All sounds very logical.

 

[FLYBOYJ]

but in 2010 they build gas turbines and nuclear reactors they dont have the skills or machinery to work on a piston engine.

Actually they probably do or can find a way to either copy or replicate the item with modern methods and materials, but for a company like RR it would take deep pockets to motivate management to find personnel to do such work. In reality, I'd bet dollars to donuts you can find machinists is some obscure location that could produce a DB crankshaft providing correct engineering data as well raw forgings are provided.

 

[VALENGO]

Rolls Royce (who examined the DB engine) cautioned the restorers of the "Black Six" not to bend the crank because they doubted very much their own ability to fabricate another one that was as "true".

I heard this a few years ago, and I always thougth that it was said during the WWII, when british tecnicians was examining a captured ME109 (and the english machinery was not able to reach the german tolerances). I realised now that they actually can´t make one of those cranckshafts!.
Sure about the age of the story?

 

[fastmongrel]

What would the benefit be of DB making a crankshaft that was so finely made. Surely it would be better to make a crankshaft that did the job but didnt require watchmakers style tolerances.

I have never heard of American or British engine makers crankshafts being particulary failure prone was this just Daimler Benz gilding the lily and making something too good. After all how long did a WWII engine last before crashing in flames or being thoroughly overhauled.

 

[FLYBOYJ]

What would the benefit be of DB making a crankshaft that was so finely made. Surely it would be better to make a crankshaft that did the job but didnt require watchmakers style tolerances.

100% spot on - the German tended to over engineer a lot of things for no reason in areas that also made no difference in the performance of the final product. In many cases this was their logisitcal undoing.

 

[fastmongrel]

100% spot on - the German tended to over engineer a lot of things for no reason in areas that also made no difference in the performance of the final product. In many cases this was their logisitcal undoing.

I had to work on the air conditioning on a Mercedes yesterday. On most cars that would involve a few screws and a few plastic clips. Not on a Merc it was all beautifully made and screwed together but lord it took a long time to take apart.

I found the problem (the owners daughter had been feeding it hair grips) and finally got it all together again. A job that should have taken an hour at most had taken me 3 hours

 

[VALENGO]

A few readings about panzers shows that german tanks was extremely fine to be war machines!. Instead be rough as T34´s they was more a precission machine, nothing more away of what was needed in that time!.