I built my own printer a while ago, Cartesian with fixed bed. Have printed several items successfully. Used other 3d slicing programs that had cura engines included and they printed fine. So, I wanted to try Cura 3.6 software. Have custom printer profile setup. It homes correctly, but second line of code that says Z15 lower build plate, well that tries to send my hot end through my fixed plate. Not Good.
When using Pronterface, Repeiter, or Craftware they know Z needs to go up , not down. I sure its simple, But so am I Want something non fiddley Don't want to correct G-code Pre run every time I print..