Originally Posted by zzyzx_xyzzy

Why eyeball the centers? Just measure left side of one hole to left side of the other hole. Or if you're really anal, measure the inside dimension, then the outside dimension, and average the two values.



You know that there are 5 bolts evenly spaced on a circle, so you only need the distance between 2 bolts and multiply by 1/sin(36 deg) = 1.701. If you can't trust that it's a standard pin circle then you'll have to make not just 3, but 7 measurements to nail down each bolt.