I think it means that I put them together, how I dont know yet.
There are a couple of ways to concatenate files. G-code files are text files, so you can open them using any program that deals with text. On windows, Notepad works just fine. There is probably some sort of code editor associated with .gcode files, so if you double click on the files, they will likely open. To use an editor to concatenate files, open both files in a text editor (separate windows) then copy and paste one file at the bottom of the other. Save the file and you are done.
A simpler way (once you have figure it out) is to use a command line command. There are lots of pages on the web that describe the process. Google “How to concatenate multiple text files into one in Windows.”
BTW, I got this message after trying to get Fusion 360 to do a NC program with tool change for the MPCNC… should I worry about it or just try and see what happens?
Not exactly sure what you did. If you used Setup/Manual NC then it does not work. I tried several commands from this menu, and nothing appeared in the .gcode file. I don’t know if this is because I have the “personal” version of Fusion 360, or if it is an issue with the Guffy postprocessor. Beyond that, Fusion will not let you combine files with different bits, so even if NC commands worked, you’d still have to figure out how to concatenate the files.
In my opinion, on the MPCNC there are a lot of reasons to not put a bit change into a single g-code file and instead use a single file for each bit and just run them one after another. While I can think of a couple of reasons you might want to pay for Fusion 360, solving this particular problem is not one of them. In particular, I’m not sure you are going to get what you want out of a combined file with a bit change.