machining
centrifugal compressor wheels.
I am not familiar with machining these items but they were probably done as Onetrack suggested on specialist lathes and other machines. I am sure I have seen photos of early ones where individual blades were set in slots in the backing disc.
More accurate machines
One way to make more accurate machine tools is to hand-make more accurate components and fit them together into a new, more accurate, machine. Then you are able to use that prototype to build your better production machines.
Templates were often used to check progress. So you machine a bit, check against the template, then machine a bit more. Accurate and relatively fast.
Seiran, have a look at the work of Model Engineer enthusiasts. A lot of traditional skills are maintained by these hobbyists and many of them are very proficient.