Hi Folks: I think they used dividers to make new dividing plates. You first layout the plate: X&Y center lines, angle line for first division ie: 35 divisions = 10.28°, and the pin hole circle. Put a solid center punch mark at "zero". Set your divider to the distance from zero to 10.28°. Now comes the improvement of accuracy: Step the divider around the circle and see if the 35 steps return to zero. If not, slightly adjust the divider and try until it matches. Once perfect, set out the holes and drill. ( I need a 35 plate and plan to make one on a rotary table using a list of the angles to 0.01°. I could also use the X-Y chart of the locations to 0.001".
Carl.