Need Help with a Drill Press X Y Table

main_cogg

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I have an older XY positioning table that is stamped Made in Sweden and sold by Willis Machinery. It's probably 25-30 years old, I've had it for 15 years. It has just started to give me some trouble, the lead screw on one axis will intermittently lock up. There is no rhyme or reason to it. Happens in both directions, works fine for awhile then does it multiple times. Usually just backing off a half turn will get it going again, sometimes I have try that several times to get it to clear. I've determined that the problem is in the bearing housing, I'm just not sure how to get it apart. I assume that the lead screw/ bearing assembly is a press fit into the housing, just don't know for sure which direction . I really don't want to break a casting. I suspect that these were imported and sold under different names, so maybe somebody has some experience with them and can give me some advice.

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Maybe try a little heat, the dissimilar metals (steel and aluminum) can corrode and stick pretty good.

John
 
Try putting some Penetrate into the ball oiler.
If the aluminum has 'galled' against the steel that might help loosen it up.
Tad of heat after awhile as John suggests.
Should, in my mind, just be a snug press-fit perhaps on a key.
 
Thanks for the suggestions but so far I don't see any aluminum that could be galled. The housing is cast iron. I'm pretty sure that there is something wrong with the bearings, I'm just not sure how to get it disassembled.
 
Is there a set screw on that collar between the lead screws and housing? If so then remove the set screw and gently tap the lead screw end to see if that will separate the dial a little bit from the housing. Then may be able to remove the dial (after removing the keyway key). Just a thought.
 
@main_cogg,

From your failure description, I would have guessed that the jibs had some play.
That would allow the table to get skewed on one axis and jam.
Running that lead-screw backwards could un-lock it, until the next time.
How do the jibs and dovetails look?

Is it just an artifact of the photo, or is the section of thread in the yellow ellipse worn significantly?
If you measure the thread crest in this section vs. the clean section are they equal?

ScreenShot073.jpg


Please let us know how it goes.

-brino
 
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If you have trouble turning ther leas screw with it removed from the table, the problem is definitely in the bearings. The indexing dial would normally be free to move on the shaft as the preload on the bearings is controlled by the nut on the end of the lead screw. The indexing dial may be locked in place with a set screw or just a friction fit. I tap with a soft faced mallet on the threaded end of the lead screw should remove any preload and the lead screw should turn freely in the bearing. If removing preload doeswn't free up the shaft, then it isw possible a bearing has galled badly and would need to be replaced. Continued tapping should increase axial play. If you see progrss, you can continue tapping or use a press to press the indexing dial off, freeing the assembly.
 
It came apart fairly easily, a few taps on the crank handle end. I was kind of expecting to find a needle bearing in there, kind of glad there isn't. I don't see any major galling , just a few raised edges that will come right off with a hard stone.
Thanks for all the help.
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Reassembly is complete, seems to be working good. I did get a little too much preload on it, felt great until I assembled it to the table. Nothing excessive, just a little tighter than I would like.
As I was doing the assembly I realized that it should not have come apart the way that it did. The two jam nuts that set the preload were completely off the threads, no doubt the cause of the problem. Disassembly should have required the index wheel to be pulled off to gain access to the jam nuts. Not sure how you'd pull the index wheel as there's nothing to grab. That's a problem for the next time.
 
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