How to set speed when adjusting Speed Graphic shutter?

How I can do by speed measure when adjusting the mechanical shutter?

I myself repaired my Graflex Speed Graphic and now need only to pull the mainspring.

But how to do it correctly, so that the value on the scale of the shutter were in line with the real values of the time?

How to do it more precisely?

The measuring method has already been found - I just could not find how to remove this Thread ...

http://lommen9.home.xs4all.nl/techni...age/start.html