Run Out On 20-inch Jet Drill Press

I've had this JDP 20MF floor model Jet drill press for 13 years. I bought it new. I've drilled up to 3/4" mild steel and cast and never have been able to stall it out. Average work is more like 3/8 to 1/2 holes mostly in mild steel and its only used a few times a week and on projects so no production stuff.

I've noticed increasing run-out at the drill tip to the point its visible. Careful bit placement in that big 3/4 chuck is required to reduce it but I can't eliminate it. Two weeks ago I put my indicator on a piece of chucked up drill rod and measured .005 run out. Up above the chuck on the arbor shaft I was getting .003 to .004 run-out.

Put in new spindle bearings and was able to reduce run-out to about .002" as measured just above the top of the chuck and again at the drill rod. I thought it should have been zero or not more than half a thousandths but maybe I expect too much?

Also, with drill turned off and indicator on the arbor shaft just above the chuck I can put finger pressure on the chuck and cause .004 to .005 deflection pushing front to rear. Much less deflection pushing side to side. I do not think there is any movement of the arbor as it fits both the chuck and spindle very tightly.

The question is what's going on there? Is that kind of movement to be expected? With the spindle locked in to the quill with new bearings I wouldn't think you'd get measurable deflection from moderate finger pressure on the chuck. Spindle is fully retracted when this happens.
Thanks for any help in solving this.
Jerry

Not an expert but a DP is not a precision machine. There are a number of things that contribute to run out - the quality of the bearings, the play between the drive sleeve and spindle, the fit of the arbor in the spindle and of the chuck on the arbor, the quality of the chuck and so on. Add to that the fact that the quill itself has a good deal of play itself and you'll always have some run out.

The important thing is that the drill goes where it needs to go once you engage the work.

mikey said:

Not an expert but a DP is not a precision machine. There are a number of things that contribute to run out - the quality of the bearings, the play between the drive sleeve and spindle, the fit of the arbor in the spindle and of the chuck on the arbor, the quality of the chuck and so on. Add to that the fact that the quill itself has a good deal of play itself and you'll always have some run out.

The important thing is that the drill goes where it needs to go once you engage the work.

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Thanks for your thoughts on DP run out. Good to remember its not a precision machine. I just wish it to be. The other Jet I have, a 17 inch floor model was a rescue press from a farm where it was used and abused. Took new spindle, arbor, spindle bearings and some missing pieces replaced and it will now hold .015 to .002 max run-out. Its back from the change over days when Orbit changed to Jet.
Best thing I've found to keep them drilling straight once engaged is properly sharpened drill bits. Dull bits seem to want to wander.

I rebuilt my Craftsman 15" DP and used Nachi bearings, new spindle and drive sleeve and it holds well under 0.001" run out near the chuck. When the drill spins you can't tell its spinning. BUT if you push sideways on the quill you can induce all kinds of run out. As long as I use a center or spotting drill and, as you said, sharp bits the drill will cut on contact and not wander. That is, after all, what I need in a DP so its good enough for me. More precision than that and I go to the mill.

Next time I need to refurb this DP it will get an angular contact bearing at the chuck end of the quill.

I had a rottenChinese bench drill, paid $25 for it ; going through dirtiest local
Junque shop found hideous dirty d.p. just like mine. Obviously from same
Patterns. Difference? Early Taiwan. No slop anywhere. Traded in mine and
$25 Moral? Know what you want, and keep looking! ..........BLJHB.

mikey said:

I rebuilt my Craftsman 15" DP and used Nachi bearings, new spindle and drive sleeve...

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Where did you get the spindle and drive sleeve from? I replaced the bearings in mine, but still have about 5 thou's of runouf.

There usually is a lot of play in the quill. You can take up some of the play by adjusting the quill lock it works best If the press is a split head type.

pstemari said:

Where did you get the spindle and drive sleeve from? I replaced the bearings in mine, but still have about 5 thou's of runouf.

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Sears Parts Direct.