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IndustryArena Forum > Machine Controllers Software and Solutions > G-Code Programing > Strange behaviour from gcode - Mach3, Fusion 360 adaptive
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  1. #1
    Join Date
    Dec 2017
    Posts
    5

    Strange behaviour from gcode - Mach3, Fusion 360 adaptive

    Hi everyone,

    I'm hoping that someone might be able to help be figure out what is going on with my Mach3 milling program, 3D adaptive tool path generated in fusion360.

    The adaptive tool path runs great for the first 47891 lines of code but somewhere on the next few lines the steppers make a noise like they've hit their hard limits and the machine coords are all pulled off, and by the time it runs a big linear move on line 47906, it's very obviously in the wrong place by several centimetres.

    I have soft limits (I think) correctly set up: before I start the program I set the machine coords to the hard limits of the X,Y and Z axes. I then switch on soft limits and jog until the soft limits come into play, correctly.

    I'm sure this is a super rookie question but it keeps happening despite the tweaks I've already made. I've been looking at different simulators and think that the issue lies in line 47892: G3 X-5.118 Y31.631 I-0.028 J0.8

    thanks in advance to anyone who reads this!

    full code file is here: https://drive.google.com/file/d/1O8e...ew?usp=sharing
    Last edited by pepsimxm; 04-01-2022 at 10:58 AM.

  2. #2
    Join Date
    Nov 2012
    Posts
    1267

    Re: Strange behaviour from gcode - Mach3, Fusion 360 adaptive

    What kind of a CNC controller are you using?

    I had a Chinese TB6500 board that would lose steps at one particular line of one particular G-code file. Worked perfectly fine otherwise. I guess that line had just the right combination of speeds/accelerations/voltages/frequencies to cause a glitch somewhere in the circuit.

    Try setting your feed rate override to 90% and running the file again.

  3. #3
    Join Date
    Dec 2017
    Posts
    5

    Re: Strange behaviour from gcode - Mach3, Fusion 360 adaptive

    Ran the program again and I believe the error actually arrives at line 47866: X-58.484 Y30.804

    For some reason the Y moves fine on that move, but the X stays put, the stepper making the weird noise like it is hitting its limits. Throws the X coords off by 58.484mm.

    I think that something in the preceding 1000 or so lines of code creates this error: I couldn't replicate the error by doing a "Run from here" from ~47000 but could replicate it when I ran from ~46000.

    Thanks CitizenOfDream; I get your logic and I'd give it a try, but the same exact error happened yesterday when I was running it with much lower feedrates. I'm not sure what CNC controller it is to be honest, it is a Denford Novamill that was converted to Mach3 by someone, not sure what they used.

  4. #4
    Join Date
    Jan 2018
    Posts
    1516

    Re: Strange behaviour from gcode - Mach3, Fusion 360 adaptive

    How good is the pc?. Not overworked?.
    I've never ran that many lines in Mach before.
    Can you possibly redo the cam program in Fusion and split it into parts of say 15,000-20,000 lines each?.
    Could be worth a shot.

    Not sure if it's that simple when doing 3D though.

  5. #5
    Join Date
    Dec 2017
    Posts
    5

    Re: Strange behaviour from gcode - Mach3, Fusion 360 adaptive

    Hi again, so I worked backwards incrementally from 47866, running the program from 47865, then 47847, 47804... etc

    I managed to narrow it down to this block of code. If I start the program AFTER this, then it runs fine. But if I run from BEFORE this, the problem happens.

    I don't know anything about gcode, but looking at these lines for anything that stands out, the only thing is the one line that is missing decimals (highlighted in bold below). I gave that three trailing zeroes but didn't fix the issue. Can anyone else make sense of this?

    G3 X31.582 Y-39.527 I-0.219 J-1.158 F800.
    X31.305 Y-40.246 I0.9 J-0.76 F791.
    G1 Y-40.384
    X31.308 Y-40.459
    X31.37 Y-40.596
    X31.467 Y-40.711
    X31.584 Y-40.804
    X31.716 Y-40.875
    X31.858 Y-40.925
    X32.006 Y-40.948
    X32.156 Y-40.952
    X32.441 Y-40.882
    X32.7 Y-40.746
    X32.92 Y-40.551
    X33.086 Y-40.31
    X33.19 Y-40.036
    X33.226 Y-39.745
    G3 X32.924 Y-39.319 I-0.475 J-0.017
    G1 X32.813 Y-39.282
    X32.7 Y-39.256
    G3 X31.58 Y-39.664 I-0.208 J-1.169 F800.
    X31.305 Y-40.384 I0.912 J-0.762 F791.
    G1 Y-40.486
    X31.312 Y-40.636
    X31.391 Y-40.763
    X31.496 Y-40.87
    X31.619 Y-40.956
    X31.755 Y-41.019
    X31.899 Y-41.062
    X32.048 Y-41.079
    X32.198 Y-41.077
    X32.473 Y-41.
    X32.723 Y-40.862
    X32.933 Y-40.668
    X33.093 Y-40.431
    X33.192 Y-40.163
    X33.226 Y-39.879
    G3 X32.944 Y-39.462 I-0.475 J-0.017
    X32.702 Y-39.384 I-0.474 J-1.065
    X31.585 Y-39.768 I-0.232 J-1.142 F800.
    X31.305 Y-40.486 I0.885 J-0.759 F791.
    G1 Y-40.624
    X31.308 Y-40.699
    X31.361 Y-40.84
    X31.455 Y-40.957
    X31.572 Y-41.051
    X31.703 Y-41.124
    X31.844 Y-41.175
    X31.991 Y-41.203
    X32.141 Y-41.209
    X32.429 Y-41.143
    X32.692 Y-41.009
    X32.915 Y-40.815
    X33.084 Y-40.573
    X33.19 Y-40.297
    X33.226 Y-40.004
    G3 X32.936 Y-39.583 I-0.475 J-0.017
    G1 X32.82 Y-39.542
    X32.701 Y-39.512
    G3 X31.583 Y-39.905 I-0.223 J-1.153 F800.
    X31.305 Y-40.624 I0.896 J-0.76 F791.

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