Major Infill Issues (no replies)

Hello,

I have been trying to get my infill correct for a few days now, and all I can manage isa few good layers and then it bubbles up and messes up!

I have tried altering:

Layer Height
Hot-End Temp.
Infill %
Infill Speed
Extruder steps/mm

I have attached images of some of the test cubes i have tried to print.

does anyone have any tips on how to solve this?

Its annoying when you see people on YouTube get their 2nd and 3rd prints to be perfect with the infill.

Thanks.