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Homing Issue

Discussion in 'Control Software' started by mrjoedave, Feb 4, 2020.

  1. mrjoedave

    mrjoedave New
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    Hi Everyone,

    I am trying to get my BlackBox set up on my cnc and am using the latest version of Control also. I am having issues with the homing cycle. I have X & Y homing direction inverted (they travel in the negative direction), it was easier because of my wiring layout. The Z homes correctly, but when the X & Y home it fails.

    It appears the X backs off the switch (I did change the distance to 3mm from the default 1mm to see if that was the problem).

    The Y just depresses the switch and I get an error that tells me to check my wiring and my retreat distance (changed to 3mm).
    • Maybe related, I do have 2 steppers to drive the Y, and one of them isn't holding position. Maybe this is causing an error? Did I miss a dip switch setting while assembling the BlackBox, that would cause the stepper to not hold position, or is it a grbl setting?
    • Is there another reason why my homing cycle would be failing? I am using the Xtension Limit Switch kit, and I've checked the wiring a number of times.

    Let me know if there is some other info that would help with trouble shooting.
    • It is a custom build, but is just a belt X & Y with a lead screw Z. Nothing crazy.
     
  2. mrjoedave

    mrjoedave New
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    P.S. The machine has been operational for the last couple of years. I am just changing it over to the BlackBox to get some more juice in the stepper drivers and for easier set up. I had not previously had limit switches installed. It was previously an Arduino with a gShield.
     
  3. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    We recommend 10mm

    Also, check that all switches function correctly in the troubleshooting tab first (press and release by hand) - pay attention that you didnt for example wire X to Y as an example and its looking at the wrong switch when it errors


    - Check wiring on second motor, maybe its intermittent because of a loose connection.
    - Check current adjustment
    - Check mechanical issue: Loose shaft coupler / belt pulley, etc slipping on the motor shaft, or belt tension too low so it skips teeth
     
    #3 Peter Van Der Walt, Feb 4, 2020
    Last edited: Feb 4, 2020
  4. mrjoedave

    mrjoedave New
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    Thanks Peter. I will change the homing pull back distance to 10mm and go through your suggested troubleshooting.

    Regarding the stepper itself:
    • I have done a lot of continuity checks on the stepper and have found no issues there.
    • The current it also good.
    • Since I am a mechanical engineer, I assumed I screwed up the electrical or software side of things and didn't even think to check the mechanical stuff. With my controller swap I didn't do anything to the stepper, but stranger things have happened. The belt is tight, but I didn't check the belt pulley was still tight. I'll check that also.
    Thanks for the suggestions.

    -JD
     
    Peter Van Der Walt likes this.
  5. mrjoedave

    mrjoedave New
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    That did it! The pulley was loose on the primary Y stepper and adjusting the pull back to 10mm fixed the homing error.

    Since the Control software defaults the pullback to 1mm, it might be helpful to have the pop-up notes suggest it be set to 10mm. I Saw in the trouble shooting that it could be a problem, but thought that tripling it would be sufficient. Since I didn't think to measure the switch throw first, I didn't consider it would default to being an order of magnitude off. I am sure there is a reason for doing it that way, and the fact that I don't have a standard configuration for my machine compounds that. Seems like it could be an easy use-ability improvement to an already nicely thought out system.

    Thanks for the quick help! I've been bitten a few times by the lack of a home position, so I'm excited to fold this into my process.
     
    Peter Van Der Walt likes this.
  6. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    False :) see our profile definitions on OpenBuilds/OpenBuilds-CONTROL all are set to 5mm by default (which should always be enough, when someone complains we say try 10mm)

    1mm might be the Grbl default
     
  7. mrjoedave

    mrjoedave New
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    Sure, I suppose I am talking about the custom config side, so maybe it's pulling from the grbl defaults and etc etc. It doesn't change my point, which is that it defaulted to 1mm and a note in the hover pop-up would have made for a more user friendly experience. It's a minor suggestion, and I don't mean to take anything away from OpenBuilds, as I've been very happy with my purchase and support. So if I am an edge case, or my application is not the primary focus, disregard the comment. My feelings wont be hurt.
     
  8. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    We have a "CUSTOM" profile in the dropdown, which sets the important parameters: See OpenBuilds/OpenBuilds-CONTROL
     

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