Seeking tips to drilling an absolutely dead-center hole w/drill press

He does not even have to turn anything. Most taps have conical points. Just chuck a tap in the drill press and use that point as a centerfider, then replace it with theintended drill bit.

If you get better results when the drill press is running I think you have excessive runout in the quill. Put a long bit ,largest diameter the chuck will take, turn drill press on. Do you see any wobble? If you have a dial indicator and a length of drill rod, you can check runout better.Sometimes the chuck can be at fault, though probably not. mike

Drilling with a twist drill in a drill press is not a suitable way to get _perfectly_ on-center holes in anything. A) any twist drill will tend to cut from a few tenths to a few thou oversized - partly due to lost motion in the system and imperfect grinding, and partly due to false edges and chips abrading the hole sides, and B) because any but a really stout drill that is _perfectly_ ground will tend to wander a bit during its cut.

When one must have holes centered to within a few "tenths", you need to pre-drill the hole a few (say 15-20) thousanths undersized (for chip relief and fast stock removal) on a milling machine, then re-index (or re-check your index of) the workpiece, and "drill" the hole with a fly cutter, finishing with a reamer.

For most work, this sort of accuracy isn't necessary. If your drill press spindle has more than a half-thou of runout, it needs servicing. If your bits drill more than two thousanths over their miked-out size, they need regrinding to center the cut. Short, stiff bits tend to wander less than long flexible ones.

LLoyd

Indeed there is no such tool that exists...

Why do you recheck after drilling? If an axis of the mill is not moving while you are cutting, it must be clamped - always.

Perhaps you mean, "boring head"?

This depends on the diameter of the drill, of course...

Yes. Just 'checking' never hurts a precision job.

Ummmm.... Blush... yep...