This article describes a method for drilling the holes for the locking pins into the field-frame rings using a metal template.
The process step by step Edit
If the washer core and the inside of the field-frame ring do not match exactly, wind spring cord by hand to the field-frame and rotate the washers to tighten the bundle. This should align the washers more or less properly into the center of the field-frame rings:
Rotate the washers so that all holes are in the same alignment in relation to the field-frame rings; this way we can rotate each washer exactly the same amount and then lock it in the place. Once the washers are aligned, select two opposing holes in each washer and drill holes to the field-frame rings through them:
Lock the metal template to the field-frame ring using a pair of tightly fitting nails:
Drill partial holes to the field-frame rings through the template. Then remove the template:
Drill the holes through the field-frame rings using the partial holes a guide: