The ones I used were close enough that they didn't bind badly in holed
drilled and tapped for the thread and bored and reamed above that for
the shank. The arrangement would have been better if the shoulder
screws threaded into a floating nut plate but it was a blind hole in
the top of a dovetail slide.

I made a successful jig to drill precisely spaced dowel pin holes in
the top jaws for a Microcentric lathe chuck by turning down 3 disks on
a freshly turned stub mandrel that fit snugly in the disk's reamed
center holes. The disks were all shaved down until any one would just
fit between the other two which were resting on the chuck's locating
pins.

To drill the top jaws I located the first dowel pin hole to the mill's
accuracy, put a pin and disk in it, chucked another dowel pin with the
second disk on it, then moved the table until the third disk would
slide between the other two. Lock the table, recheck fit, drill and
ream. All 3 top jaws fit onto the chuck with finger pressure.

Jim Wilkins