2D Contour Bug, CNC Router

[Cave_Master]

Hello,

I encountered a new one today.  Well into running a program today our CNC Router froze up.  I was standing near (within 6 feet) of the machine when I heard a low vibration and felt it reverberating through the floor.  I looked at the machine, the spindle was spinning above the part and the machine was not in motion (at least motion visible to the naked eye).  The machine control however was flying through code.    I stopped the machine and checked the drivers for alarms, there were none.   I jogged the machine and ran the spindle, all sounded good.  I then  opened the program I was running and re-saved it, starting just before I had the issue.   I ran this program and immediately the same issue occurred.   

I thought this was odd so I sent the two programs and a video of the machine to ShopSabre tech support.  The technician pointed out that there are many small moves in the code.   I didnt think anything of it, our programs are usually well over 100,000 lines and run time close to one hour.  He then showed me that we had tiny CW arcs (G2) followed by tiny CCW arcs (G3).

Here is the code that crashed it, our unit is G22 (mm)  This is occurring during a ramp in, I have leads turned off but ramp turned on.  

G2 X803.949 Y241.448 Z15.499 I6.45 J-0.068 F15000.
G3 X803.948 Y241.396 Z15.495 I6.449 J-0.089
G2 X803.949 Y241.448 Z15.491 I6.45 J-0.037
G3 X803.948 Y241.396 Z15.488 I6.449 J-0.089
G2 X803.949 Y241.448 Z15.484 I6.45 J-0.037
G3 X803.948 Y241.396 Z15.481 I6.449 J-0.089
G2 X803.949 Y241.448 Z15.477 I6.45 J-0.037
G3 X803.948 Y241.396 Z15.473 I6.449 J-0.089
G2 X803.949 Y241.448 Z15.47 I6.45 J-0.037
G3 X803.948 Y241.396 Z15.466 I6.449 J-0.089
G2 X803.949 Y241.448 Z15.463 I6.45 J-0.037
G3 X803.948 Y241.396 Z15.459 I6.449 J-0.089
G2 X803.949 Y241.448 Z15.455 I6.45 J-0.037
G3 X803.948 Y241.396 Z15.452 I6.449 J-0.089
G2 X803.949 Y241.448 Z15.448 I6.45 J-0.037
G3 X803.948 Y241.396 Z15.445 I6.449 J-0.089
G2 X803.949 Y241.448 Z15.441 I6.45 J-0.037
G3 X803.948 Y241.396 Z15.437 I6.449 J-0.089
G2 X803.949 Y241.448 Z15.434 I6.45 J-0.037
G3 X803.948 Y241.396 Z15.43 I6.449 J-0.089

I duplicated the contour operation and in one operation selected the two problem contours, and in the other selected the other 6 contours, posted it, and all was good.

Looking at my old code (and current code) we have very little G3 moves on these parts and in the section pasted above, those moves are full of G2 and G1 not G3.  Here is an example:

G2 X716.818 Y1784.311 I6.424 J-0.579
G1 X717.272 Y1788.461
G2 X717.313 Y1788.768 I6.412 J-0.701
G1 X717.935 Y1792.698
G2 X718.038 Y1793.211 I6.371 J-1.008
G1 X718.936 Y1796.911
G2 X719.087 Y1797.435 I6.268 J-1.521
G1 X719.672 Y1799.185
G2 X719.826 Y1799.6 I6.117 J-2.045
G1 X720.519 Y1801.28
G2 X720.724 Y1801.727 I5.963 J-2.46
G1 X721.537 Y1803.337
G2 X721.793 Y1803.796 I5.758 J-2.907
G1 X722.723 Y1805.316
G2 X723.003 Y1805.736 I5.502 J-3.366
G1 X724.047 Y1807.176
G2 X724.395 Y1807.615 I5.222 J-3.786
G1 X725.548 Y1808.945
G2 X725.911 Y1809.33 I4.874 J-4.225
G1 X727.168 Y1810.56
G2 X727.593 Y1810.941 I4.511 J-4.61
G1 X728.949 Y1812.051
G2 X729.425 Y1812.405 I4.086 J-4.991
G1 X730.876 Y1813.385

There was a quick work around, but I wanted to bring this to Autodesk's attention.  I dont really have a good way to check the code so for now if this happens we will only realize that in machining.

This is with parts that were made in the same file and with the same operations that were used back in July the last time this part was made.  This is why I believe it may be a bug.

[seth.madore]

Kip, it's quite likely something got changed, either in the Kernel or Fusion itself. Can you share a file that was producing this combination or G2/3's

[Cave_Master]

Sure thing.   I will email it to you.    Are you looking for GCode or a F3D file?

[seth.madore]

Both!