I’ve only shaped 2 boards and I relied on Greenlight’s manuscript like a crutch. For anyone unfamiliar, they provide a PDF image for 2 rail styles showing you where to mark measurements at the 12” marks and wide point for a 2.5” board. Then they provide a chart according to board thickness to adjust the the rail marks as needed.
they also provide a chart for the measurements at the wide/thick point for alternative rail styles (50/50, down rails, soft rails, etc.). However for the alternative styles they do not go into detail about where to go with the rail bands in the nose and tail.
I know a seasoned shaper can make the rails they want with their eyes and feel. However for a n00b like myself, is there a simple rule of thumb or mathematical factor for unveiling rail band measurements as they taper into the nose and tail?