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Thread: CNC Accuracy issues

  1. #13
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    Default Re: CNC Accuracy issues

    Quote Originally Posted by Angelok View Post
    I'm not sure if this is the right place to be posting this, (I'm new here) so if it's not any suggestion on a better location would be appreciated.

    I recently purchased a used machine (Digital Tools RD-903-1) and for the most part it works well but it does give me some accuracy issues. It's have a 5' x 10' cutting area with stepper motor and a Porter Cable router, I'm using Vcarve Pro for the drawing and a older version of Mach3.

    What happens is if i cut a small circle say round 1.5" diameter, it isn't perfectly round, but if i cut that same circle over and over again it is constant. If I cut a larger circle say around 8" diameter it fine. I did a test, where I put a 4' x 8' sheet on the table and cut out 11" x 11" squares and there weren't all the same. It was only a small difference but it seems that the accuracy is different at different placed on the table.

    Does anyone have any ideas on what I can do or what the issue is.

    Thanks,
    How is the machine build 5' x10' is a big machine to be only using a router for a spindle, post a photo of the machine

    If your 11" x 11" squares where different you need need to check the calibration of each axes to get the steps/per set correct, or you may have backlash also

    Try cutting the 1.5" at a slower speed, it sounds like you have flex as well, it should cut the same as the 8" just may be getting flex and backlash going to fast when cutting

    Mactec54


  2. #14
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    Default Re: CNC Accuracy issues

    Quote Originally Posted by Angelok View Post
    Hello everyone,
    I want to say thanks to everyone here, this forum is awesome!
    I did some testing on my machine today to see if I could isolate some of the issues and I’m starting to think this may need more work than I anticipated.
    First what I did was set the machine to zero and ran a few patterns. I wanted to make sure that it went back to zero each time. It was perfect!
    The next thing I did was cut out some 10” x 10” squares. I cut out 24 pieces form a sheet 34” x 92” so 3 pieces along the Y axis and 8 along the X axis. (See attached)
    On the X axis they were all the same, not perfect with a bit of a bow but not my concern at this point (baby steps). The Y axis on the other hand… the first row was 9.9375” the middle row was 10” and the last row was 10.03125”. As the machine move to the right the cut get larger.
    I later did another test with 11.5” x 11.5” pieces and got similar results.
    What would cause the measurement to increase?
    Thanks
    Gantry Y Axes may not be square to the X Axes, the Y Axes may have a calibration problem or wear in the drive what ever that is, it looks like you have a light weight construction so expect to have flex as well

    Mactec54


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    Default Re: CNC Accuracy issues

    Quote Originally Posted by Angelok View Post
    Hey Peter, Thanks for the info. i think what your talking about is still a bit too advanced for me I've found some inaccuracies on my X axis. i'm not sure what it is yet but I feel much better about the machine now that I'm starting to isolate the issues. Once I have that figured out I'll look into what you were talking about.

    Once again thanks for putting in the time and sending the info.
    Don't get confused with what he has posted I believe Peter is confused himself, it is amazing what some people will post, I think what he post is over his head as well

    Mactec54


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CNC Accuracy issues

CNC Accuracy issues