Results 1 to 7 of 7

Thread: Backlash comp: does other axis pause during?

  1. #1
    Registered
    Join Date
    Oct 2004
    Location
    usa
    Posts
    24
    Downloads
    0
    Uploads
    0

    Backlash comp: does other axis pause during?

    I'm not sure if this is the right place for this question, but I have a question about backlash compensation :

    With the typical PC based G code to stepper pulse software, when the X axis has a backlash specified, how does it effect the motion of the other axis?

    Example: cutting a circle with X and Y, X has backlash compensation of a small amount. As the X axis gets to the point where it will reverse direction, ( the top of the cut ) the motor stops, then does a fast move on the opposite direction to cover the backlash, then it proceeds with the 'normal' cut speed.
    Fine.
    But does the Y axis stop while the X axis does the compensation? It should, I think.
    Also, does the axis lash compensation motion have predictable acceleration ramps and max velocity parameters to prevent motor stalls and dropped steps during the lash move?

    Are all of the popular products about the same in these regards? ( Mach2, cncpro, etc ).

    -Les


  2. #2
    Registered
    Join Date
    Jun 2004
    Location
    United States
    Posts
    450
    Downloads
    0
    Uploads
    0
    In turbocnc, yes the other axis pauses. There are no other settings (that I have found) to adjust the speed/time that it takes to do the compensation.

    Mach2, it has a setting for backlash, but from what I read in the manual, and what I have seen when using it, it doesn't actually correct anything while cutting. The manual says something to the affect that it will compensate by trying to keep the motion goibg in one direction. I'm assuming this is for the wizards that it supplies. But the only thing I can think of that could be done like that, would be drilling holes. Someone correct me if I'm wrong please.

    Not sure about any other software.


  3. #3
    Community Moderator ger21's Avatar
    Join Date
    Mar 2003
    Location
    Shelby Twp, MI....USA
    Posts
    22211
    Downloads
    0
    Uploads
    0
    I don't think any backlash compensation works really well. They may work ok for some applications, but not all. Your best bet would be to try to reduce or eliminate the backlash on your machine.
    Gerry

    Mach3 2010 Screenset
    http://home.comcast.net/~cncwoodworker/2010.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


  4. #4
    Registered
    Join Date
    Jul 2003
    Location
    southern indiana
    Posts
    126
    Downloads
    0
    Uploads
    0
    On mach 2, when the direction on that axis changes, the axis will travel an additional amount specified in the backlash screen at a speed that is a % or rapid.

    I am using it on my mill, as I have not yet upgraded to ball screws yet.

    It works, although is not as good as removing backlash to start with.


  • #5
    Registered
    Join Date
    Jun 2004
    Location
    United States
    Posts
    450
    Downloads
    0
    Uploads
    0
    Thanks ty1295 for that. I must have misunderstood the manual. Or maybe it was just an older version? Anyway thanks, once I get a new hard drive (mine went pffft) I'll have to check it out.


  • #6
    Registered RotarySMP's Avatar
    Join Date
    Mar 2004
    Location
    Vienna, Austria
    Posts
    1073
    Downloads
    0
    Uploads
    0
    Early versions of TurboCNC would stop all moving axis, apply backlash to the onethat was reversing, then continue. This of cause cause stalling of an axis running at full speed, asked to stop sudenly and then restart at full speed after a pause.

    Version 4 decelerates all moving axis to a stop, applies backlash to the one changng direction, then accelerates all axis back up to speed.
    Regards,
    Mark
    www.wrathall.com


  • #7
    Registered
    Join Date
    Oct 2004
    Location
    usa
    Posts
    24
    Downloads
    0
    Uploads
    0
    TurboCNC sounds like they implemented backlash the best way. Does anyone know if Kcam4 or cncpro do as good of a job? I think that this backlash feature is rather tricky to do just right.
    -Les


  • Similar Threads

    1. Ballscrew Basics
      By Swede in forum Linear and Rotary Motion
      Replies: 101
      Last Post: 04-16-2012, 09:09 PM
    2. 4020 4th axis problems
      By little bubba in forum Fadal
      Replies: 3
      Last Post: 06-13-2005, 10:08 PM
    3. Z axis backlash
      By maxxdog21 in forum Benchtop Machines
      Replies: 2
      Last Post: 03-01-2005, 11:12 PM
    4. Backlash with worm drives ?
      By andy_ck87028 in forum Mechanical Calculations/Engineering Design
      Replies: 9
      Last Post: 02-02-2005, 05:40 AM
    5. Z axis backlash adjustment help sieg x3
      By replicapro in forum Benchtop Machines
      Replies: 0
      Last Post: 11-07-2004, 01:13 PM

    Posting Permissions



    About CNCzone.com

      We are the largest and most active discussion forum from DIY CNC Machines to the Cad/Cam software to run them. The site is 100% free to join and use, so join today!

    Follow us on

    Facebook Dribbble RSS Feed


    Search Engine Friendly URLs by vBSEO ©2011, Crawlability, Inc.