Run out on a drill press?

[Wade Lippman]

I have a PC drill press that has so much run out that you never quite know where the hole is going to be. I don't use it much so I have put up with it, but a nice used DP is on CL, so I might bite the bullet.
I asked the owner what the run out on it was. He replied:
"So I removed the chuck and measured the run out on the Taper, it is .001" with the quill seated ".

Maybe I am confused, but that seems pretty meaningless to me. Don't you measure it at the end of a drill, where it might be 500x what it is on the taper?

[Steve Demuth]

It's certainly not a useless measurement. If the runout at the bottom of the taper is .001", you know that the bearings are reasonably tight and the taper is properly centered in the quill. I would also measure at the chuck, but runout there could be a problem with chuck (which is much more easily fixed, obviously, than in the quill and bearings) or seating of the chuck in the taper.

[Jeff Duncan]

Nope, you measure at the spindle and work your way out from there. If the spindle is good then all else can be worked on, if not:(

If the chuck is off a bit, it can be fixed, rebuilt, or replaced. If the bit is off.... well its a bit, it's probably going to be off, especially if its a cheap bit:rolleyes: It's the spindle that needs to run true.

good luck,
JeffD

[Dan Friedrichs]

If you've got runout at the taper, no amount of precision in the chuck or the bit will fix that, I guess. A bad chuck is pretty easily/cheaply replaced if it's the cause of excessive runout. If you don't have any other known straight rod, you could bring a router bit and measure runout on that with it chucked.

[robert wiggins]

I once worked in a shop where an estimated 75 percent of the drill bits were bent. The end of a drill run out could be a poor measure of press condition.

[Martin Siebert]

.001" at the "bottom of the taper" is very good if the machine does not have opposed tapered bearings. In fact, I seriously doubt you are going to see one any better, again, that is with sealed ball bearings. Ball type bearings cannot be made without some play, you have two so in theory it doubles. Now, if the machine has twin opposed tapered bearings they are adjustable and you should be able to adjust the quill to dead zero lash, which should {but may not depending on how straight the quill is} make it run with zero runout. That is the purpose of having those type bearings. If it has sealed ball bearings {non-adjustable} and the runout gets much over about .002" then a new set should get it straight. Like anything, you buy high dollar bearings, you see low to very little runout. You buy Asian "cost effective" bearings you will see more.
Same with the chuck...buy a cheesy one and you could be worse, spend some money on a really good one and you will have something worth using. There is no "free lunch" with machines.

[John K Jordan]

I have a PC drill press that has so much run out that you never quite know where the hole is going to be. I don't use it much so I have put up with it, but a nice used DP is on CL, so I might bite the bullet.
I asked the owner what the run out on it was. He replied:
"So I removed the chuck and measured the run out on the Taper, it is .001" with the quill seated ".

Maybe I am confused, but that seems pretty meaningless to me. Don't you measure it at the end of a drill, where it might be 500x what it is on the taper?

I don't know if this was mentioned, but instead of measuring run out at the end of a drill I mount a precision drill rod in the chuck and use a test indicator on that, top and bottom. Tighten the chuck in all three holes. If there is acceptable run out you know things are good and any wobble will be a problem with the bit. If there is unacceptable run out, it might be in the chuck itself and removing it and checking the quill will tell. You can mount just an arbor in the taper and measure that.

[Jim Becker]

Remove and reseat the taper, too... ;)

[Bill Dufour]

He did it right. Measuring at the chuck means the arbor could be bad at both ends or bent, the chuck internal taper could be bad and the chuck could be bad and the drill could be bad at both ends.
Bill D.

[glenn bradley]

I don't drill a lot of holes with the quill seated. I wonder why he didn't just go ahead and measure it with the quill extended while he was at it?

[Bill Dufour]

I don't drill a lot of holes with the quill seated. I wonder why he didn't just go ahead and measure it with the quill extended while he was at it?

Quill seated is the least possible runout with the existing bearings. If the quill extended runout is too much the quill can be bent straighter. I had to straighten my quill to reduce runout. I got it to about 0.002 then realized it was pointless to go beyond. It has probably snagged and bent the quill since so the runout today is probbably a little worse but still plenty good for wood working.
If you ever snagged a bit and felt the dp stop for a fraction of a second the quill has probbably lost it's accuracy