Ignoramus3537 fired this volley in
:

I have a DRO. The issue is, if I move to point (1.2345, 6.5432), and
plung the drill down, will the hole really be in thast point or
somewhere close due to drill wandering.

Iggy, you understand he doesn't mean plunge the 43/64" drill. He was
talking about a short, rigid spotting drill.

Unless you've got lost motion in your system, it should be close enough;
WAY tighter than your spec on those mounts.

It cannot hurt, after dialing to your location, to lock both ways and
just barely gently snug up the quill lock. Re-check that the way locks
didn't move the table, and that the quill lock didn't push the quill out
of line. Unless your machine is quite worn, it shouldn't.

I personally wouldn't drill such a hole in that thin stock. I'd
drill/ream or bore it to finished size. A trick I'm partial to is to
mount a boring head in the tailstock, and use the head's vernier to
adjust the hole size. There's no difference in the finished job between
doing that or just using a boring tool on the post, but it is faster and
more convenient for me to do it that way if I don't already have a boring
tool holder in the toolpost. (I have a homebrew indexable post that is
anything BUT "quick-change").


LLoyd