How to Drill Perfectly Centered Holes in Round Stock!

[engineer steve]

Drilling perfectly centerd holes in round stock, using my homemade milling machine.

[DIYer]

Thanks engineer steve! We've added your Round Stock Center Drilling Setup to our Drilling and Drill Presses category,
as well as to your builder page: engineer steve's Homemade Tools. Your receipt:

Round Stock Center Drilling Setup by engineer steve

tags: drilling, centering

[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

[mklotz]

Even if you get everything aligned down to the atomic level, there is still no "perfection". The electrons become probability clouds and the very fact of you observing alters the outcome.

[engineer steve]

You guys are absolutely right but I don't think that 'perfect' has a fully defined definition. When you say something fits perfectly it generally means that it is perfect for your standards, I guess that's why tolerances have been invented to give a solid definition when it comes to size. I appreciate your thoughts

[mklotz]

The only "perfects" I can think of are limited to events defined by humans as opposed to events in which nature has a hand or subjective evaluations are considered.

You can bowl a perfect game but only because humans have defined a finite scoring system and strikes are immediately determinable. Having your interior decorator decide the perfect color to paint a room is impossible.

[th62]

The easiest way to drill a hole in the centre of round stock, if it's small enough, put it in the drill chuck and clamp a drill/centre dill in the vice.

[engineer steve]

That sure will work but will not be as accurate, if the drill chuck doesn't perfectly line up with the vice or chuck on the table, you will force it out of precision. The method in the video can be adjusted down to 0.01 mm (0.4 Thou) or beyond, depending on your setup.

[th62]

That sure will work but will not be as accurate, if the drill chuck doesn't perfectly line up with the vice or chuck on the table, you will force it out of precision. The method in the video can be adjusted down to 0.01 mm (0.4 Thou) or beyond, depending on your setup.

Obviously, if the work is spinning and you bring it down onto a centre drill it will centre itself. It's no diffent from drilling a hole in round stock on a lathe with a centre drill in the tailstock.

Obviously the centre drill has to be centred, but it's not that critical.

I have no need to do it thisvway because I have a lathe, but I did it thisvway for many years before I bought a lathe.

Still, if your happy doing it your way, good luck to you

There are many ways of doing things, accepting 'your' way as the best, most accurate and onlynway of doing things is a fool's errand.

[rgsparber]

Here is another way:

1) mount the round stock in the 3 jaw chuck with at least 1/2” sticking out. Do not clamp the chuck to the table yet.

2) slide the chuck around until the stock slides into the drill chuck

3) tighten the drill chuck while helping the 3 jaw slide into alignment

4) clamp the 3 jaw to the table

5) loosen the drill chuck and mount the spotting drill in it

You do pick up error in the drill chuck plus spindle runout.

I hope all see how this idea evolved from many of the comments in this thread. All of us are smarter than any one of us.

Rick