The problem of gaps, real holes on the horizontal closing faces, called pillowing, of our prints is a fairly common problem. Like all the common problems analyzed so far, there are not many causes that create it, so you get to the resolution rather quickly.
Pillowing problem: Increasing the top layers
Perhaps the most common cause is the too small size of the totally solid layer of closure, to be sure to close a model well we should make sure to set at least 6 “passes” of material and then 6 layers using the thickness 0.2 mm, go to 8 for layers of 0.1 mm and at least 10 for the thickness of 0.05 mm. The count is quite simple: multiply the height of our layer by 6, in the case of printing at 0.2 mm. A practical example, the value that we will have to set for the parts under and above the shell on the slicer that will form the G-Code will be 1.2 mm.
Already this shrewdness will minimize the chances of finding ourselves with the problem of pillowing, but, if it does not completely solve our problem we will have to consider other cases.
Pillowing problem: Increasing the Infill
Many times I have been unable to properly quantify the weight of printed objects. This happened especially in the early days when I used the 3D printer. The same happens with the calibration cube. Looking at it, our mind expects a certain weight and inevitably it is lighter.
This phenomenon that at first may seem strange is easily understood by analyzing the value we give to the infill. The infill, which translated means filling, determines how much our print will be “full” inwardly. A fill value of 20% means that our print will be “full” at 20%. That is, “empty” for the remaining 80%, the four-fifths of the inside of our print will be composed of air!
Obviously to save filament and time we are inclined to use the least amount of internal filling possible, so much so that the inside is not visible!
Many times, however, the infill is the only support to which the upper layer of closure can cling, missing that and not using the small tricks explained in the article on bridges and scaffolding, we can find ourselves with a result not really satisfactory, leaving real holes on a face that we would expect completely smooth.
To overcome this problem we will have to increase the percentage of infill (in the photo above the example of the adjustment with Cura), or change the texture, almost all slicers have the ability to use different textures for filling. Let’s choose the type of infill with the thickest weft, this will provide more support points to the extruded material. It will make it easier for the printer to print horizontally.
Pillowing problem: Use ventilation (if possible)
In case we don’t want or can’t increase the infill, we can use ventilation.
The ventilation of the newly extruded filament is essential when the nozzle has to travel great distances without supports: in fact, if the newly extruded filament is well ventilated, it solidifies immediately and remains in the suspended position in which we want it. Ventilation helps to eliminate Pillowing problems.
Pillowing problem: Underextrusion
In the event that the efforts made up to this point do not give the desired effects only 1 possible cause remains, the underextrusion! In this article we have dealt with the subject in depth.