The weak infill is a bad problem. That’s cause infill is the backbone of the 3D print and plays a fundamental role. Both for the final robustness of the printed model and as a support for the layers that are supported. As already mentioned in the articles to avoid pillowing or holes on the faces of the print, and you must avoid as much as possible to have a weak filling.
Weak infill: Here are some tips
Let’s start by saying that normally the filling is printed much faster than the walls of the model. This speed is sometimes counterproductive and excessive.
The extruder cannot keep up and creates a phenomenon of underextrusion. Most of the time the mere 20%/30% reduction in speed solves the shortage of infills.
If the reduction in speed is not enough to have a more resistant infill, you can try increasing the percentage. Already passing from a 10% to 25% infill will make the filling much more solid and therefore more resistant.
Changing the plot can also have advantages sometimes. Choosing a thicker weave can strengthen the model without changing its settings.
Some software also allows you to change the thickness of the walls of the infill, which instead of being the width of the extruder are 2/3 times larger. This contributes exponentially both to reinforcing the model and to avoiding problems of inconsistency of the infill, which makes the infill weak.
Obviously, doubling the line that the software follows to spread the infill will cause the slicer to halve the number of lines used, expanding the open spaces. The recommendation we feel we should make is: if you decide to use the double sized infill line, remember to double the infill value, triple it, and so on.