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  1. #21
    Join Date
    Nov 2014
    Posts
    729

    Re: accuracy issues over x axis

    For those of us who are more visual, can you post a photo of your machine and where these pieces are that you're cutting?

    David
    David
    Romans 3:23
    Etsy shop opened 12/1/17 - CurlyWoodShop

  2. #22
    Join Date
    Jan 2014
    Posts
    60

    Re: accuracy issues over x axis

    Quote Originally Posted by difalkner View Post
    For those of us who are more visual, can you post a photo of your machine and where these pieces are that you're cutting?

    David
    Sure, other things to note yesterday installed new pinion gear, and swapped racks with X and nothing has changed. Another thing I noticed is that one or both of the racks I had off had a decent bow in it I could mesh the teeth on both and rock them back and forth. How tight are most of you tightening down the pinion gear? Mine has always been relatively tight because if I don't crank them down I can push the Z axis a very small amount with the motors on and engaged. I'm still wondering if racks may be the issue, but before dumping more money at it, I'd like to know if anyone else has suggestions.

    Sent from my Nexus 6P using Tapatalk

  3. #23
    Join Date
    Mar 2003
    Posts
    35538

    Re: accuracy issues over x axis

    I don't see how it could be the racks.
    It could be 100 different things, but I think it's a mechanical issue causing it, that you're not seeing. I don't think throwing money at it will solve it, but you never know.
    The fact that you see the same thing in Mach3 and UCCNC almost surely means it's mechanical.

    Unless it's your g-code??
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

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

  4. #24
    Join Date
    Nov 2014
    Posts
    729

    Re: accuracy issues over x axis

    Photos help, at least for me. Out of curiosity, since the X cut is parallel to the X axis, or appears it should be, when it is making the cut then Y shouldn't be moving at all. Since these are long cuts can you watch the Y motors and see if they move at all? They should be stationary. You won't even have to be cutting material to find out, just put the bit an inch above the surface and run it dry. It sounds like it's mechanical, as Gerry said, but I would want to rule out that one motor isn't somehow moving during the cut.

    David
    David
    Romans 3:23
    Etsy shop opened 12/1/17 - CurlyWoodShop

  5. #25
    Join Date
    Mar 2003
    Posts
    35538

    Re: accuracy issues over x axis

    Put a V bit in there, and make two grooves the length of the table, one at each side of the gantry. Watch the DRO and make sure it's not changing during the cuts.
    The two grooves should be parallel over their entire length.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

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

  6. #26
    Join Date
    Jan 2014
    Posts
    60

    Re: accuracy issues over x axis

    Yup I am assuming mechanical too I have tested with and without gcode with the MDI and can still verify the error. I'll be in the shop tonight to test a couple more things.

    Sent from my Nexus 6P using Tapatalk

  7. #27
    Join Date
    Jan 2014
    Posts
    60

    Re: accuracy issues over x axis

    Quote Originally Posted by ger21 View Post
    Put a V bit in there, and make two grooves the length of the table, one at each side of the gantry. Watch the DRO and make sure it's not changing during the cuts.
    The two grooves should be parallel over their entire length.
    I'll try that tonight too

    Sent from my Nexus 6P using Tapatalk

  8. #28
    Join Date
    Apr 2008
    Posts
    51

    Re: accuracy issues over x axis

    Should you post your g-code to rule that out?

    I had issues in the past with my pinions slipping...I drilled through the pinion and the shaft and secured them with a spring pin

    Sent from my SM-G900V using Tapatalk

  9. #29
    Join Date
    Jan 2014
    Posts
    60

    Re: accuracy issues over x axis

    Here's the gcode I've been using on the tests

    profileTestingX.zip

    Sent from my Nexus 6P using Tapatalk

  10. #30
    Join Date
    Jan 2014
    Posts
    60

    Re: accuracy issues over x axis

    Ok bear with me spent all ####### weekend on this, I think I have figured it out. It started with me just out of a hunch measuring how far the z axis actually moved on top of the extrusion, which is what I used to have it calibrated to when I build the machine and guess what over the length of my calibration I was a 1/16th short. So I re-calibrated from the top of the extrusion not from the table with a vbit. Checked square in middle of table and I'm basically spot on square. I took my digital angle gauge along the top rail and somewhere in the middle range the steel rail bows down at first then back up again, and continues upward (also put a straight edge on it to verify). Basically I start going out of tram somewhere after the midpoint and it escalates over the rest of the length. Also it explains why I usually have ridges on my spoilboard after surfacing only on the right side of the table. I'm going to assume this is the problem since I have tested almost every suggestion and idea I could think of.

    Attachment 372194
    Attachment 372196

  11. #31
    Join Date
    Apr 2008
    Posts
    203

    Re: accuracy issues over x axis

    Attachment 372260 like this but mounted on the x axis and indicator on the smooth side of the rack. Sorry it took so long ot respond

  12. #32
    Join Date
    Apr 2008
    Posts
    203

    Re: accuracy issues over x axis

    then run yor x axis far left and far right to see how far out your rack is out of alignment.

  13. #33
    Join Date
    Jan 2014
    Posts
    60

    Re: accuracy issues over x axis

    Quote Originally Posted by davy182 View Post
    then run yor x axis far left and far right to see how far out your rack is out of alignment.
    Ok that makes sense, I think I will try that on all my Axis. I'm pretty confident it's the x axis rail causing my problems, but when I swapped racks they do have a bow to them as well.

    Sent from my Nexus 6P using Tapatalk

  14. #34
    Join Date
    Jan 2014
    Posts
    60

    Re: accuracy issues over x axis

    Quick update, got the new rails from CRP, installed them last night. Then over my lunch break ran home to test another cut and it seems the problem is fixed. Both parts seemed to match and line up. I will continue to test and verify with the larger project. But I wanted to thank all of you for the suggestions, and helping me narrow this down.

    Sent from my Nexus 6P using Tapatalk

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