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Y Axis Lag

Discussion in 'CNC Mills/Routers' started by Bigmontel, Jun 29, 2019.

  1. Bigmontel

    Bigmontel Well-Known
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    Can anyone explain how to fix the lag between my two Y axis’ when switching directions? It may be a bit hard to see in the video but its like both y axis’ are a half inch off or something on their screws??
    Any advice is appreciated. I’m scratching my head on this.
     

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  2. Bigmontel

    Bigmontel Well-Known
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    Black box and control are my jog tools.
     
  3. Bigmontel

    Bigmontel Well-Known
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    Another video
     

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  4. Bigmontel

    Bigmontel Well-Known
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    Are my videos not working?
     
  5. sharmstr

    sharmstr OpenBuilds Team
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    Video is working.

    Couple of things to check

    First, make sure that your gantry is square. Power off the motors close to one end. With a ruler, measure the distance from the end plate to the X gantry on both sides. If off, adjust to make square by spinning the motor coupling by hand.

    Second, double check your lock collar on the side that's lagging. Make sure its not loose.

    Let us know how it goes.
     
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  6. Bigmontel

    Bigmontel Well-Known
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    Thank you, I’ll give both a try and see how that goes.
     
  7. GrayUK

    GrayUK Openbuilds Team Elder
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    That "clunk", at the beginning and ending, of movement doesn't sound right. Sounds like there is play being taken up somewhere. :rolleyes:
     
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  8. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Sounds mechanical in nature to me too. Loose couplers/pulleys likely
     
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  9. RV6APilot

    RV6APilot Well-Known
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    I had a similar problem and found that 1. I didn't have the coupler mounted to the motor correctly. Make sure the set screw is on the flat part
    of the motor shaft and 2. make sure you have all the eccentric nuts and anti-backlash blocks tighten properly. Once I did this my machine was spot
    on.
     
    #9 RV6APilot, Jun 30, 2019
    Last edited: Jun 30, 2019
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  10. Bigmontel

    Bigmontel Well-Known
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    I’ll definitely check my couplers and blocks when i get home.
    I checked that my gantry was squared and that’s pretty much spot on.
     
  11. Bigmontel

    Bigmontel Well-Known
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    ok...update.
    1. I checked that I’m squared on gantry and pretty much every other angle.
    2. Pulled collars, screws, and flex couplings off Y axis. Then reinstalled.
    At this point, still getting same lag from one side with the sort of loud start and stop.
    3. Swapped connections from Y & Y2 motors at the motor connectors and now get lag on opposite side with same amount of start stop noise.
    4. Tried adjusting amps on the Y & Y2 on blackbox with no positive result.

    Even when turning off power and re-squaring the gantry once power is applied It’s a significant lag that forces my gantry to be out of square by about a quarter inch.
    The gantry rolls smooth and stays squared without the Y screws.

    Any ideas?
     
  12. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Shoot a video so we can listen and look a little closer please :)
     
  13. Bigmontel

    Bigmontel Well-Known
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    I’ll take video after work today to give a better idea.
     
  14. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Also, elaborate on how you test

    - feedrates used
    - etc

    As its impossible to 'lag' as both are literally in parallel on one signal, its something else... Just a question of what. Mechanical is most likely.
    But too high a feedrate can also skip steps
     
  15. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Also, output of Grbl settings ($$)
     
  16. Bigmontel

    Bigmontel Well-Known
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    So here’s a couple short clips of my issue.
     

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  17. Bigmontel

    Bigmontel Well-Known
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    I took video of my settings Peter, pretty much standard workbee 1010 settings because I’m not experienced enough yet to know what to change.
     
  18. sharmstr

    sharmstr OpenBuilds Team
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    For what its worth, Windows 10 cant play the video without paying for a new video codec. So, I only get audio.
     
  19. Bigmontel

    Bigmontel Well-Known
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    Hmm... ok. That’s almost as odd as my cnc issue.. thanks, I’ll try get a video people can actually see.
     
  20. sharmstr

    sharmstr OpenBuilds Team
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    Maybe others can see it. I'm only telling you whats happening for me.
     
  21. sharmstr

    sharmstr OpenBuilds Team
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    I just downloaded another video player and can see them now.

    I had the same thing happen two days ago. The sound its making is common with wiring issues. I had my axis rack, just like yours. Anyhow, I had moved my blackbox and one of the motor wires on one of the Y motors came loose (as in it pulled out a bit, but not completely out) and was arcing. I could actually see the sparks. Anyhow, check your wiring.
     
  22. Bigmontel

    Bigmontel Well-Known
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    Ok, good to know. So you had the noise and the weird lag issues?
    Ok, I’ll definitely give it a look. That would make sense since it changes sides when i switch motor connections.
     
  23. sharmstr

    sharmstr OpenBuilds Team
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    Yep. And it might not be at the blackbox. It might be at the motor. It might be somewhere in between the connectors.
     
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  24. Bigmontel

    Bigmontel Well-Known
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    You were spot on Sharmstr. Much appreciated.
    Took my x axis cable and used it on the laggy Y axis and it works like a champ.
    Thank you for your feedback, helped me out big time.
     
  25. sharmstr

    sharmstr OpenBuilds Team
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    Funny enough, when it happened to me I was pretty stoked. Up until then I had told people that was their issue without having any first hand experience with it. Glad you are sorted. Now, next thing you need to do is calibrate you steps per mm. You have the default settings which are a great starting point, but you need to dial it in. Check out the wizards in the Tools and Wizards menu.
     
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  26. Bigmontel

    Bigmontel Well-Known
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    I’ll definitely get more into dialing it in now that all the bugs are worked out. Thanks for the help.
     
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  27. Mushy

    Mushy New
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    Just thought I'd add my novice two cents to the mix as I came here with the same problem.
    One y axis always seemed to take the lead as it were.
    Checked all the wiring first and found one slightly loose connector so re-wired, problem still existed.
    Turns out the locking collar on the stepper motor wasn't perfectly lined up with the flat side on the motor drive(hope that makes sense)
    So there was just enough movement to get a half turn before it grabbed and worked properly.
    Took the whole lot apart lined up and seated everything properly and it runs beautifully.
    Hope this give someone else with a similar issue another option to check.
    Cheers
    Mush
     
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  28. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    A drop of loctite (non permanent type) between motor shaft and the pulley/shaft coupler prevents it rattling loose over time
     

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