Dial indicator education for drill press run out

[John T Barker]

345810
This is my dial indicator (Yuasa 320-002ST) and I rigged it up to rest on a drill bit as I turn the chuck of my drill press by hand. The indicator moved 8 little lines, which I interpret as .008". Is this too much? I'm drill a lot of holes and getting some chipping and tear out, enough to make the pieces unusable. Could this be the cause? I'm feeling more like it is the wood grain since I perceive a difference in the pieces that tear out/chip and those that don't (I see shavings coming out of the drilled holes on those that don't while the ones that chip seem to have waste that is fiberous.)
Feedback?

[Dave Cav]

I would check on the shank of a couple of different, good quality drill bits and average the results. A section of ground drill rod stock or a ground steel dowel pin from the hardware store would be even better. The runout can be coming from a number of different places: loose bearings, a low quality or bad drill chuck, or a bent drill bit. But yeah, .008 seems a little high even for woodworking. What kind of drill press are we talking about?

[Cary Falk]

Sounds kind of high to me also. How far down from the chuck are we talking about? It would be better to use drill rod as previously stated. Could be the drill bit, the mortise taper, or the chuck. Depending how hard you are turning the chuck by hand, you could be adding some of that error yourself. The easiest thing to do/chcck is to pop the MT chuck out, clean off and out the taper with mineral spirits and reseat the taper. I did that to a Steel City drill press and it made a huge difference.

[Doug Hepler]

John,

In line with earlier comments: to gauge runout you need a piece of straight rod. If the rod is not straight you will only chase your own tail trying to reduce the runout. Also, how far from the chuck are you measuring .008" runout? My idea of an accepted standard for WW is .005" 1" down from the jaws of the chuck.

I bought a set of good quality brad point bits for use in drilling wood (from LV/Veritas). "Normal" drill bits are actually meant for drilling metal, although they often give satisfactory results in wood.

Next, I would question the speed with which the bit enters the wood.

I hope this helps

Doug

[John Densmore]

To put things into perspective that is 1/128". Depending on how and where you are measuring, I find that to be perfectly acceptable.

[John T Barker]

To put things into perspective that is 1/128". Depending on how and where you are measuring, I find that to be perfectly acceptable.

Let's not get sloppy here, it's 1/125.

[Lee Schierer]

John,

I bought a set of good quality brad point bits for use in drilling wood (from LV/Veritas). "Normal" drill bits are actually meant for drilling metal, although they often give satisfactory results in wood.

I agree completely. Regular twist type drill bits create a lot of tear out in wood.

[Frederick Skelly]

To put things into perspective that is 1/128". Depending on how and where you are measuring, I find that to be perfectly acceptable.

Yeah, it's 1/125, but John D's point is valid, isn't it? Seems like, unless you're a patternmaker, that much runout in wood just shouldn't matter. Am I missing something?

[John Densmore]

>> Let's not get sloppy here, it's 1/125.


Exactly, rounding to the nearest mil 1/125 = 1/128.

For all who think 8 mil is too much run out. If I gave you a piece of maple with two XX" holes. One was drilled with a press that has 5 mil run out and the other has 8 mil run out. How do you determine which hole is which?

[John T Barker]

>> Let's not get sloppy here, it's 1/125.


Exactly, rounding to the nearest mil 1/125 = 1/128.

For all who think 8 mil is too much run out. If I gave you a piece of maple with two XX" holes. One was drilled with a press that has 5 mil run out and the other has 8 mil run out. How do you determine which hole is which?

That's what I'm hoping...that for what I'm doing that amount of run out should not matter. It seems the pieces that blow out on me have weaker grain.

[Ellery Becnel]

Being a machinist, .008 is too much. I can live with .002. I am talking the equipment tolerances.
Some of the woodworkers that I work with say that is good enough for wood, because it will move.
To me, I would want to hold a tighter tolerance, because of movement. If your equipment is repeatable,
then your cuts, holes, etc. will be cleaner, and more precise. Is it always needed, not always. I am sure
some people will disagree with my thoughts. That's OK, I understand it is wood, but your woodworking
equipment is not. And it was not manufactured to be purposely out of tolerance.
Just my thoughts. A machinist who enjoys woodworking.
Ellery Becnel

[pat warner]

In my view it is possible to get hole to hole centering (with a bad press) to ~.002". Not withstanding, you're always correcting for the anomaly.
And the first hole could be +/- 1/64" from its coordinates, (with a +/- .008" runout). Moreover, even the best of brad points, will wobble as they enter.
And that can produce tearout.
Brad point drills have no way of finding their target; they're only supported on one end, the chuck end. As such, they're at sea until they enter your sample.
If your hole centers are willy/nilly, you have to over drill and often that puts your whole assembly into stress.
Fine Drilling is way under-rated in woodworking. It's an annoyance, like changing a tire.
You can't drill in metals with that kind of runout. Unless you're drilling access holes for grommets and such.

[David Kumm]

You should also check the hole size in relation to the drill bit. Some bearings ( angular contact or self aligning) only tighten under load so you can get more runout when turning by hand than you will get when actually drilling. You also might release the chuck, check the tang and hole and put back on. That sometimes corrects things but drill presses are notorious for being poorly built now. Dave