/diy/ - Do It Yourself

anyone here ever used the whitworth three plates method? it's a (theoretically) simple process for achieving extremely flat surfaces using three relatively flat metal plates. any documentation I've found is very surface-level. there's a tutorial series on youtube that seems pretty simple to follow except for a few key points:

1 - I don't have a lathe. he surfaces the three pieces he starts with in his lathe so there's less lapping to do and so the starting faces are more or less parallel. could I take three rounds to a machine shop and ask them to flatten them for me? or would they consider it a waste of time?
2 - both the bandsaw and circular saw methods he used to cut the grooves on the surfaces are super sketchy, does anyone have a better way of cutting them? are they really necessary?