Thanks Thanks:  0
Likes Likes:  0
Needs Pictures Needs Pictures:  0
Picture(s) thanks Picture(s) thanks:  0
Results 1 to 7 of 7
  1. #1
    Join Date
    Apr 2009
    Location
    Kingswood
    Posts
    652

    Default Ballscrew Nut Re-fit

    My CNC re-furbish project on a Kondia turrett mill has languished for a few years.
    But, I can now devote some time to it and the first issue has arisen.

    The X-axis ball screw nut was separated from the screw after some problems.
    The shaft leading up the helix is Dia 25 mm, and I 'assumed' that diameter would allow the nut to simply slide off.
    Not so, the nut jammed immediately.
    Tried working it back and forth and eventually removed the ball return tubes and extracted the balls.
    Not easy because they are heavily greased - got 103 balls.
    Quite a few gouge marks in the shaft, but of no consequence because this area is non-utilized.

    Intend to clean it all up and re-fit with a central oil system.
    Included is new brush wipers if they can be obtained.

    Previously, the Y-axis nut but was removed by sliding onto a Dia 27.2 mm tube, retained on the tube while
    machining the screw, then re-fitted without any drama.

    Looking for suggestions:
    - source for brush wipers,
    - ideas on on how to get the nut back onto the helix.

    Thanks,
    John.

  2. #2
    Join Date
    Jan 2012
    Location
    Melbourne
    Posts
    85

    Default

    I managed to put back together a ballscrew once by cleaning everything up and then feeding the balls in through the tube hole. Keep going until they start coming out the other end, keep letting out and feeding new ones in until you think youíre letting ones out that are properly packed. The first few in wonít be well packed because youíll be struggling to keep the screw and nut aligned while you feed the balls in. Then fill the return tube with balls and bolt it back on.

  3. #3
    Join Date
    Jan 2012
    Location
    Melbourne
    Posts
    85

    Default

    I managed to put back together a ballscrew once by cleaning everything up and then feeding the balls in through the tube hole. Keep going until they start coming out the other end, keep letting out and feeding new ones in until you think youíre letting ones out that are properly packed. The first few in wonít be well packed because youíll be struggling to keep the screw and nut aligned while you feed the balls in. Then fill the return tube with balls and bolt it back on.

  4. #4
    Join Date
    Apr 2009
    Location
    Kingswood
    Posts
    652

    Default

    Thanks for the suggestion, I wondered whether that was a viable method.
    My nut has 2 return tubes, with each end buried within the nut when the retaining clamp is fitted.
    It will need quite a bit of dexterity, possibly some ingenuity, but worth a try.
    One could possibly fill the nut with one tube installed, fill the the other nut at the work bench, hold the balls with a grease, then invert that tube and install.
    The nut will be full when all 103 balls are inside it and it revolves smoothly around the screw !

    I have started looking at Youtube clips and searching for suitable descriptions.

    John

  5. #5
    Join Date
    Apr 2009
    Location
    Kingswood
    Posts
    652

    Default

    Attached is one of the ball return tubes showing the damage inflicted by a previous worker (!). Ball Nut Return Tube Compr.JPG This tube, and its mate, would still operate but they are clearly not ideal. The other parts required are the end wipers - some wear/distortion. Got on to the Australian representative of THK ballscrews, they have no spares and claim trying to contact the factory would be pointless. Posted a thread on LinuxCNC Forum to see if anyone there can suggest a spares supplier. This post is just to see if anyone here might have a suggestion. As an aside, placed a query through Alibaba for bellows to keep swarf out of the nut in future. John

  6. #6
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    54
    Posts
    5,167

    Default

    What's the bore of the tube - it looks like the sort of thing that may be able to be bent around a mandrel.

    Michael

  7. #7
    Join Date
    Apr 2009
    Location
    Kingswood
    Posts
    652

    Default

    Michael,
    The problem with a new fabrication is the special machining at the ends - it would take multiple attempts to get it correct.

    One small step forward was a quote/order on a Chinese company through Alibaba for protective bellows.
    They were not too expensive, but could easily be not suitable.
    Report with photos when I get them.

    I found a Korean address/site that sells redundant and used electronic and associated mechanical components, including ballscrews.
    They do not have an English version of their website and it appears they do a lot of business after a walk-in inspection of the goods, with prices in Korean WON.

    Found on their listings a used ballscrew of the same type as mine.
    Price is not too high, but so far, they have not answered my email.

    Any suggestions on how to get assistance with contacting a Korean company ?

    John

Similar Threads

  1. Ballscrew Run-out
    By electrosteam in forum METALWORK GENERAL
    Replies: 11
    Last Post: 17th Jan 2011, 07:38 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •