Hi, Artrans
Don't be in a hurry hear, You need to do some research on G-code, Lot's of info hear, Top of this page under Support, Documtation section you'll find Mach3 manuals that will give you lot's of info.
Your g-code will cut your rod in 3 part's as it is now, You need edit the dxf and remove some of the lines, Look at the second picture hear, This is how the outer part of the rod should be drawn.
Don't get frustrated, It took you awhile to learn the in's and out's on transmissions also, I'd Guess.
Chip