neburmine

Im new here so if i did anything wrong please tell me. So im trying to print this peace on my ender 3 and is should fit on the build plate, but i cant slice it because of the gray areas on the left and right. I tried slicing it in creality slicer and it worked. Only the print qualty of cura is better so id rader use cura, I was wondering does anyone know how to remove/make the gray boxes on the side smaller? I already tried to make the build plate bigger in cura but the boxes stay. Also have removed skirts. And tried changing some support setting but those things do not help.