Unanswered Smallest gap between printhead and bed

Hi All,

I have a Robo3D Beta and the switch that should tell the printhead to stop prior to hitting the printbed was set too low, I have raised it up and now when I home the printhead it doesn't smash itself into the print bed. I'm wondering though what the initial gap should be between the printhead and the print bed. 1/8" ? 1mm? 1"? Any guidance is appreciated. --Barry Steenbergh