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Y axis travel distance off. How to Fix?

Discussion in 'CNC Mills/Routers' started by jda70az, Oct 13, 2022.

  1. jda70az

    jda70az Well-Known
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    Hi.

    Hoping you guys can help me.

    What is the calculated steps/mm for a 1040mm ACME lead Screw?

    And just to let you know I don't have a computer hooked to my CNC machine. I am using Interface.
    But I can hook up black box to my computer and change GRBL settings.


    I checked my Y axis travel distance and it's off. Sent 28" =711.2mm actual distance traveled
    28.25 = 717.55mm. Off by 25.4mm.

    In black box it's set to $101 = 199.100mm

    So what's the math for setting this correct? I watched the videos and I'm still confused.

    is it 197.308?
     
  2. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    If its our Leadscrews, 199.1 steps per mm (Theoretical 200, but in practice the rolling process is a little off and its closer to 199.1)

    8mm pitch per rotation,
    1/8th microstepping of the BlackBox * 200 physical steps of the motor = 1600 microsteps per rotation.

    8mm per rotation at 1600 steps per rotation = 1600/8 = 200 steps per mm

    Rather than bothering to do the Math, just use the Wizard :)

    Use as long a distance as possible (the default 100mm is just a safe-ish suggestion to avoid crashes, longer distances = more accurate)

     
  3. jda70az

    jda70az Well-Known
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    So 200*(711.2mm / 717.55mm ) = 198.23 ?
     
  4. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Theoretically yes. Apply, reset the BlackBox, then test again
     
  5. jda70az

    jda70az Well-Known
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    That worked. It's only off now by 1mm
    Thanks man you are super helpful.
    I remember now, you explained this to me like a year ago but I forgot. :banghead:
     
    Peter Van Der Walt likes this.
  6. David the swarfer

    David the swarfer OpenBuilds Team
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