Can't find it in the search area, but when I open a .stl set everything as desired, it makes 2 .nc files. At first I thought it might be for 3D Objects to mill both sides. What's it really for?
The Openbuilds Fusion360 post creates an .nc file per tool. so 2 files means you have 2 tools selected. This is commented inside the .nc files, which explains it all. They are plain text, you can read them with notepad. Also, the post options include an option to turn this behavior off, in which case selecting multiple tools would generate an error. Note this does not mean you cannot use multiple tools in your project, it means you have to manually post per tool since GRBL (the software inside the controller) cannot do tool changes.
