How to Drill Perfectly Centered Holes in Round Stock!

[rgsparber]

"Perfect" is a rather high standard. Indicating center, as you demonstrate, is probably the best that can be done but there are uncontrolled errors.

The stock will never be perfectly round, the spindle will always have runout. The center drill will never drill exactly on center so the drill, even if perfect, will not drill on center.

As you point out, the machine will deflect while drilling which also throws off "perfect."

Ataining the best possible accuracy for a given machine is the best anyone can do. In most cases, this is damn good.

Rick