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

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.

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.

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.

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.