Spindle running through stock instead of retracting and moving the next step above it. Gcode issue or something else?

[aokere]

Hello all, I'm trying to figure out what is causing our 3axis CNC's spindle to randomly plough through stock when moving to the next step instead of retracting and moving above it. I've attached photos of what this looks like, and where I stopped the machine the second time it happened. I ran the same file twice, and it did this action in different places each time. This has happened on our machine before, but lately it has been happening with a lot more frequency- to the point where I wouldn't be surprised if it happened on the next file I try to cut.

When this happens, it tends to cause the machine to freeze (we use LinuxCNC, and it will usually show that the spindle continues to move when it is not.) and forces me to restart the program. I've posted this to other forums first and the feedback I've gotten is that it seems to be a gcode issue. I simulate all my files every single time- this of course never shows up on the simulations. Has anyone had this happen? How can I locate the problem within the gcode?

This forum doesn't allow me to upload the exact .ngc file that is doing this (it accepts .nc but I dont know if it's possible to convert .ngc to .nc) so I uploaded the .f3d file, and the toolpath that these problems are happening in is under Setup3, Pocket2. 

Thank you!

[matty.fuller · Accepted solution]

If you ran the same file twice and got different outcomes I would say it is definitely your machine at fault and not anything going on in Fusion. It' conceivably possible that the Gcode is not resetting a modal condition or calling an incorrect tool offset, but if you ran the same file from the same starting conditions it should do exactly the same thing.

First step is to figure out where in the Gcode this is occurring and then inspect the code to see if the machine is or isn't doing what it's told. You should look for the block number it's at when the issue occurs and note that down, then take a look to see what's meant to be happening.

With regard to .ngc/.nc they're all just text files. You can change the extension or copy out the contents.