Results 1 to 3 of 3
  1. #1
    tesla500 is offline Plastic
    Join Date
    Nov 2013
    Vancouver, BC

    Default Ballscrew backlash - Tree 325 CNC

    How much backlash is acceptable in ballscrews? I'm looking at a used Tree Journeyman 325 CNC, the X axis has essentially 0 backlash, the Z axis has 0.0005", but Y has about 0.002-0.003" depending on position. I think the thrust bearing is not pretensioned correctly and is contributing about 0.001-0.0015" of the total, based on indicating the end of the screw while jogging the axis. I didn't have time to figure out what backlash comp was set in the Dynapath 20 control, but judging based on how the screws turned when reversing, it's minimal, < 0.001"

    The machine appears to be in good condition, ex-Boeing equipment. Asking price is $4300. Does this seem reasonable? Could the backlash be reduced by reballing it, or is it a more major repair to get the backlash out?


  2. #2
    heat is offline Plastic
    Join Date
    May 2012
    Vanc., BC, Canada


    If the Y axis backlash varies .002-.003 all along the axis that would be a different problem than the backlash being "zero" everywhere except a particular section of the screw. That much backlash in just one section would indicate wear in that section of the screw. That would leave you with the option of having the screw re-ground (a number of shops advertise this service) or getting a new ballscrew.

    If it's even along the axis, then, yes, probably the thrust bearing needs to be tightened down - or replaced.

  3. #3
    hitandmiss is offline Stainless
    Join Date
    Jul 2010
    Rochester, NY USA


    Troubleshot a variable backlash issue (Y axis on a Mori MV-40).
    The screws holding the ball nut into it's bracket were stretched slightly and the screws holding the bracket to saddle were also loose.


Tags for this Thread


Posting Permissions

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