I am constantly amazed at some of the era service tools. This one dropped in my lap a week or so ago.
Found an article from Motor Record for June, 1920 :
Sawyer-Weber crankpin turning tool
Years ago, I used a similar tool to round up the throws on my REO 2 cylinder crankshaft. The throws are off set where a conventional crankshaft grinder can not do the job.
Nice, Phil - here's my Ha-Lee set:
Mine looks like the one Steve Tomaso has, only mine has a longer handle. They can work well, and some can even do a crankshaft in the car in a pinch. You do have to be very careful to not leave any sharp edges to your cuts. If the cutters are properly sharpened, that is not too difficult. Any sort of a sharp edge will lead to cracks and broken crankshafts.