If you’re experiencing objects having the bottom layer having jagged / visible lines that are not smooth, that can only mean that the heated bed is incorrectly leveled, meaning there’s a greater distance between the nozzle & the build plate, this results in having extruded filament not mending together properly.
This can be remedied by going through the leveling calibration process with the 0.3 mm spacer card we assign with every Craftbot 3D printer. First of you must make sure to increase the distance between the brass nozzle and the build plate as much as possible to avoid damage to the kapton sheet applied build plate, this can be done by tightening the black knobs found under the heated bed.
Now, you must select the ‘3 bull’s eye‘ icon within the settings tab. This will initiate the calibration procedure, going to three designated positions where you must set a minimal distance between the nozzle and the build plate using the spacer card. The distance must be as much that you can freely move the spacer card between the bed and the nozzle with little resistance. You must do this distance calibration on all 3 locations. Once done, you should carefully check if the nozzle runs into the build plate and if the distance is different on multiple locations, if not then you successfully leveled your build plate!