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Thread: CNC Accuracy

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  1. #1

    Join Date
    Mar 2021
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    1

    CNC Accuracy

    Hi,

    Was wondering is anyone has had a similar problem, I'm trying to help my brother with his cnc machine. its using a ball screw on the z and belts on the x and y, 1 motor on x & z and 2 on the y nema23's . Y and Z seems to work fine. When I move X 300cm in Mach3 it moves 300 but when I move it say 25 it only moves to 22. The annoying thing is when I move it 25 x 12 it lands on 300 again, its breaking my brain

  2. #2
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    Join Date
    Aug 2008
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    325

    Re: CNC Accuracy

    Is the axis calibrated correctly are the steps per inch set correctly and is there any mechanical slop in the axis / Lose preload nut ball nut sliding in its holder sounds like something shifts before screw moves ?

  3. #3
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    Join Date
    Jan 2005
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    12203

    Re: CNC Accuracy

    Quote Originally Posted by marlo086 View Post
    Hi,

    Was wondering is anyone has had a similar problem, I'm trying to help my brother with his cnc machine. its using a ball screw on the z and belts on the x and y, 1 motor on x & z and 2 on the y nema23's . Y and Z seems to work fine. When I move X 300cm in Mach3 it moves 300 but when I move it say 25 it only moves to 22. The annoying thing is when I move it 25 x 12 it lands on 300 again, its breaking my brain
    As gabedrummin has said it sounds like you need to calibrate each axis

    Open the Settings Tab ( Mach3 )

    Just above the Reset Button, you will see the Axis Calibration , just follow the instructions and you can then set the Steps Per mm or inch for each axis

    You need an accurate gauge to do this, for a rough setup you can use a tape measure then you will need a gauge block or something that has a precise measured number, you can look up some videos on YouTube on how to set step/per in Mach3

    The longer you make this measured movement the more accurate you can get your machine setup, 50mm works but 300mm would be better
    Mactec54

  4. #4
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    Join Date
    Apr 2005
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    252

    Re: CNC Accuracy

    Quote Originally Posted by marlo086 View Post
    Hi,

    Was wondering is anyone has had a similar problem, I'm trying to help my brother with his cnc machine. its using a ball screw on the z and belts on the x and y, 1 motor on x & z and 2 on the y nema23's . Y and Z seems to work fine. When I move X 300cm in Mach3 it moves 300 but when I move it say 25 it only moves to 22. The annoying thing is when I move it 25 x 12 it lands on 300 again, its breaking my brain


    Are you referring to cm or mm? when you say you ask for 25 and get 22 is it only the same part of your belt drive you get this error or is the error seen no matter where you do the move?
    I'll get it finished sometime after I start it.....

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