[ATTACH] Found this helpful explanation too
All super interesting stuff! I guess it still does not answer the initial question though. I worked in a crankshaft shop as a kid back in the '70s. We would send cranks out to be nitrited, or "tuff trited", which was hardness process for the outer layer, or skin of the material. The bigger the crank, the more the piece swelled with the process. We got to the point were we could predict the amount of growth on some of the more common unit, and account for it. Otherwise, we had to re-grind, or polish more material off. On a crankshaft, a lot of strength is in the radius of the journal; the corner where the bearing surface meets the counterweight. After all was said & done, we would sometimes "stress relieve" the part, by putting it in an oven for period of time, with a long, natural cool down period. I bet that some of the different models may vary in their construction, and not just by year. A larger displacement engine, with a huge stroke, would require a different process than a smaller engine, with a short stroke. Merry Motoring, RF.
This is how Ferrari cranks have been supplied to Ferrari by a British firm since at least the mid 60's. I have similar pictures from the days of the 330's. I have never seen proof they were machined from a solid steel bar as has often been stated. A good friend from Cosworth is familiar with the supplier, I am not. One person may be responsible for assembly but not machine work as the photo implies. Now crank machining is fully automated. Many years ago were done by humans on very old tired machines. All retooled around the days of the BB or so and again since then. In the mid/late 70's, early 80's machine work was getting pretty sloppy. Now machines are spitting out engine parts like Famous Amos cookies.
Back in my GM days, Landis was the leader in crank shaft grinding / lapping machines. Amazing machines to see operate.