Drill Press Accuracy (Lack Off...).

Nogoingback

Nogoingback

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So, my DP is a Taiwanese Jet (17") that I bought new about 26-27 years ago. I've repowered it, installed a quality chuck,
and done some work to align and balance the pulleys. For most of what I do with it, it's been satisfactory, but if I need to drill a reasonably accurate hole, It almost always wanders off. Now, before you guys tell me there's only so much I can expect from a DP, I know this. I don't expect milling machine accuracy by any means. But I'd like to do better, and before you ask for numbers, I don't have any for you. I've tried everything I can think of. I measure, layout and center punch carefully, raise the table as high as I can manage, make sure everything is locked down, clamp the work to the table or in a vise, use screw machine drills to minimize deflection,
etc.
I just came back from the shop where I put an indicator on the table, extended the spindle to what I figure is a typical drilling position
and push/pulled on the chuck side to side. I got about .025 of play, so I'm thinking bearings could at least be part of my problem.
They aren't noisy or rough, but they are 25+ years old and probably not the best bearings to start with. Ideas?
 
Others will have more experience than me, but changing the spindle bearings in my dad's drill press transformed it from borderline useful to very acceptable.
 
Nogoingback said:
That's good to know David. What kind of DP was it?, and how old?
Click to expand...
It was some no-name, bench-top machine. Nothing of note and certainly no factory parts.
 
Was just thinking some more...
I'm not sure where I saw this but I understand that some drill press heads are split which allows there to be more tension put on the spindle reducing the potential for it to move in the head casting.
Here, two bolts have been added to compress the head around the quill to remove 'slop' from wear.
IMG_0905.jpg
 
Yes, I've seen that on some DP's, but mine isn't like that. I does have a screw/locknut on the side of the head that
engages a slot on the quill. Adjustment of that minimizes slop in the quill, but I've already done that.
 
On almost every Taiwan or Chinese drill press I have ever seen, they use cheap shielded bearings. All of them have similar construction. There are two spindle bearings inside the quill and two drive sleeve bearings at the top. These are the only bearings in there and they are simple to change. I did my Sears Taiwanese drill press some time ago. You can see the write up here.
 
I think 0.025" of waggle is lots! After more than 2 decades of use, maybe it deserves a make-over.
There is not a lot else that can move anywhere sideways except the middle of bearings relative to their outside races.
Take it apart. Go after the bearings.
Then also start getting picky about the chuck condition. If the chuck is spinning without any bad run-out, but the drill rod it is holding does have run-out, the chuck jaws may need some help - or just replace it with a nice keyless type. :)
 
You have two sources of play. 1, between the quill, and the drill press body. And 2, between the spindle, and the quill. Tackling each are different. Try to measure each before deciding on a method to tackle a fix.

Are you centerpunching holes before attempting to drill? that can make a big difference in any drills ability to start a hole where you want it.
 
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