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Gantry strikes Limit Switch hard

Discussion in 'CNC Mills/Routers' started by Michael Bauer, Jan 3, 2023.

  1. Michael Bauer

    Builder

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    Good day,
    I have recently purchased and assembled a Lead 1515 and am running into a single issue with the X axis when Homing. The Gantry activates the Limit Switch and does not back off until the Y axis switch has been found. To my knowledge and from what I have found here on the forums, this is operating normally. My issue is that I have been through 3 limit switches so far on the X axis as the Gantry activates the switch and continues to move, depressing the arm until it pops out of the switch (breaking or deforming the plastic enough that the arm is no longer held securely and fall out again the next time the switch is activated, or depresses it enough that it is now jammed in the down position. I have checked and double checked the wiring and switch locations; all wires are where they are supposed to be. I have also verified in the troubleshooting tab that the proper switches are activating when depressed.

    Any assistance in this matter would be greatly appreciated. Thank you. IMG_8316.jpg
     
  2. Giarc

    Giarc OpenBuilds Team
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    Is it possible your x axis switch is plugged into the y axis slot? Is the Y stopping before it should?
     
  3. David the swarfer

    David the swarfer OpenBuilds Team
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    that is my first thought too

    my second thought is that the switch is there to be triggered but must not act as a physical stop, the frame of the machine must do that in the event of a failure to stop when the switch is triggered.
    like this
     
    Peter Van Der Walt likes this.
  4. Michael Bauer

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    I have re-verified again that the correct switch for the correct axis are plugged into the correct slot


    As for the location of the switches, my build is identical (for now) to the videos on the assembly page. I will note that by default $26 homing switch debounce delay is set to 250ms, reducing that down to 5ms has reduced the frequency of occurrence however, it has not eliminated the issue entirely.
     
  5. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    What is your homing seek and feet rates set to?
     
  6. Michael Bauer

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    Homing Search Seek rate is set to 2000 mm/min
    Homing Locate Feed rate is 100 mm/min
     
  7. Giarc

    Giarc OpenBuilds Team
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    Homing Seek rate is very fast at 2000mm/min. Try 500. Jog your machine close to the homing positions and then give it the homing command. That way you can use a reasonable seek speed but not have to wait an eternity for your machine to jog all he way back and up at 500mm/min. Then change your $24 to 50mm/min for more precise homing. You could probably then go back to 250ms for debouncing ($26).
     
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  8. David the swarfer

    David the swarfer OpenBuilds Team
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    to further reduce your homing wait time, always park the machine near home before you turn it off.
    a macro can do it with one click simplicity
    Code:
    G21 G17 G90
    G53 G0 Z-10
    G53 G0 X-10 Y-10
    
    that will move all axes safely to 10mm short of the home switches.
     

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