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IndustryArena Forum > MetalWorking Machines > Hardinge Lathes > How can one determine if X-axis ballscrew is being lubed without taking it apart?
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  1. #1
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    How can one determine if X-axis ballscrew is being lubed without taking it apart?

    Is there a way to quickly check if the X-axis ball screw is being lubed properly? When I turn the X-axis from the front cover panel using a 3/16 allen key, it seems very rough - almost as if I can fee the balls clicking around in the ball screw itself. This thing should be as smooth as butter, shouldn't it?

    In another thread, I'm having problems with a failed X-axis - I believe, among other things, the ballscrew may not have been lubricated properly. I have an air-oiler that I presume was working when I bought it, but upon further inspection during the failure, I noticed the oiler wasn't dripping. So I increased it. A lot, actually, for a while to ensure lube got everywhere... but I don't really see lube coming out. I see evidence of it on the main way, but I can't tell if it's getting to the ball screw. Now it's dripping once per 15 seconds or so. About double the recommended dosage. The excess will probably flow somewhere...

    I removed one steel bracket holding the rear bellow from the rear of the X on one side (it's cramped in there...didn't want to disassemble everything, and one screw wouldn't allow me to remove that annoying wire shield) and peeked through the small hole without bending all the brackets holding the bellow.

    Well, I know what a well-lubed ball screw ought to look like - it's usually glistening with oil, and nice and shiny. This one looked... dry and had a mysterious white film on it. I really didn't get a good look though. I could be wrong. But I was expecting glistening, surely.

    Can anyone tell me how to inspect the X-axis ballscrew for lube without taking it significantly apart? Like, for example, where should I look to see the excess oil dripping? Isn't there some sort of tube feeing into the ballscrew nipple? Or does hardinge just drip onto the ballscrew from somewhere?


    Torin...
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    www.walker-tech.com

  2. #2
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    In a normal lube system there is metering devices at the end of each lube point, these have a small fine filter in them that clog over time, the only solution is to replace the meter if this is the problem.
    They have an orifice size number stamped on them.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  3. #3
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    What is it? A CHNC?

  4. #4
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    Yes, sorry. I assumed people would just know that. :-)

    It's a CHNC1 circa 1986? using the 810T Siemens control using OIL, not water-based coolant (ser no 2625, iirc)

    I was up inside the rear bellow trying to get a peek at the ballscrew because when I twist it from the front access panel using an allen key, it doesn't turn very smoothly - I feel little ... bumps? And wonder if the ball screw or the ball bearings inside aren't somehow galled. Anyway, while I was up in there looking at the ball screw, I didn't see the glistening shiny tracks of the ballscrew. Instead, it looked rather dry and had this white film in the bottom of the track. That could be remenants of white lithium grease, or simply my imagination. But at any rate, NOT seeing the shiny glistening surface of a ballscrew groove concerned me so now I want to check to see that it's being lubed properly.

    My CHNC1 drawing shows three separate lubrication tubes going to the block that I believe connects to the ball screw nut. Somehow, but the drawing isn't clear to me, but I'm guessing the tube somehow connects through this block to the top nipple of the ballscrew nut. I am reluctant to remove the bellow for fear of damaging it - it's quite cramped in there, but if necessary, I will.

    Strangely, the hardinge documentation says *nothing* of how the X-ball screw is lubed. For that matter, it also doesn't appear to say how to replenish the reservoir that supplies the X-ballscrew with lube. I have a tank for the hydraulics, and I have an air-line lubricator. I suspect it is the air-line lubricator that lubes the X-axis, and not a direct feed from a pump. That also would explain the 1/4 lube lines. Such a large tube should only be required if air is the delivery mechanism. Otherwise, 1/16" lines would be in order with the little metering units as Al suggested.

    I will try tonight to slide the motor to loosen the belt (disengage from the motor) so I can feel the ball screw turn without any cogging from the belt. Correct me if I'm wrong, but the ball screw should be butter-smooth, shouldn't it? If not, I might be looking at a ball-screw replacement. Yay.


    Torin...
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    www.walker-tech.com

  5. #5
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    there are many models of Hardinge lathes, good thing for you is that I am currently retrofitting 2 similar machines, mine are chnc II SP's heres a link to the thread. http://www.cnczone.com/forums/vertic..._mach_3_a.html

    Look at my pics to help:

    The 3 air lines on the back are not for the ballscrew only one is. The only way to check is to take off the black plate, once done you will have a small air line in the middle that feeds directly to the ballscrew. Loosen the ballscrew and back the ball screw out (by turning the screw) so you can get access to the nut and air line, remove the air/oil line, is there oil in it? If not then your lines are clogged. Goto the front of your machine, on the left hand side there should be a panel with the air/oil reservoir, one of those lines feed oil to your ball screw, not sure which, so loosen them all and back feed the oil and clean out the line, my oil reservoir was super nasty. Take some pics and post them so I can further help ya .

    And yes it should be very smooth, and if you feel detents then it might not be your ball screw that shot, it may be the thrust bearings in the ends, I think one of mine are bad. There should also be oil all over the ball screw atleast where it travels. Look at my pics and see what I mean. One is brownish cuz the guy used water based coolant EWWW.

    Mike

  6. #6
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    Check this out, and look near the end, there is a full diagram of the oil line lube system

    http://www.hardingeus.com/usr/pdf/Pa...09500-0049.pdf

  7. #7
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    Quote Originally Posted by mike^3 View Post
    Check this out, and look near the end, there is a full diagram of the oil line lube system

    http://www.hardingeus.com/usr/pdf/Pa...09500-0049.pdf
    Hey so what was causing the bumpy feel? I have exact same symptoms and would love to know!

  8. #8
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    Re: How can one determine if X-axis ballscrew is being lubed without taking it apart?

    FYI for anyone in the future reading this.... I isolated this to the motor, I assume it is a permanent magnet motor. I think there is probably nothing wrong with the machine.

  9. #9
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    Re: How can one determine if X-axis ballscrew is being lubed without taking it apart?

    Quote Originally Posted by dbsharp View Post
    Hey so what was causing the bumpy feel? I have exact same symptoms and would love to know!
    It was the belt cogging as expected. At the time, I was inexperienced and reluctant to remove the belt because the manual showed adjusting proper tension using a dial indicator to a high degree of precision (a few tenths maybe, or something like that) and was something I didn't initially want to get into if I didn't need to... but I eventually took off the belt and turned the ballscrew with an allen key - it was silky smooth as expected.

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