The V-Groove Exterior Overcut controls where the Blade Retractsfrom the Matboard(not the Fallout)on the Exterior cuts of the Outside Cut of the Non-Oval V-Groove.
The Exterior Cut is where the Blade Plunges or Retracts from the Matboard (not the Fallout).
If the Exterior Overcut on the Outside Cut of the V-Groove is cut Too Short, Increase the Exterior Overcut.