I have spent ages debugging this problem but I can't figure out what I am doing wrong.
I have a Wanhao duplicator i3 (Prusa i3 clone) and until recently I used Wanhao's adapted version of the Cura slicer. But it's quite an old Cura version and I wanted to make use of the improved supports in the new Cura.
Unfortunately it seems like I just can't get the infill in the newest Cura to work. I copied all the settings from my Wanhao branded Cura version and printed the same file.
This is the result:
The infill is shaped like many tiny pillars. They are super fragile and while they do support material to be printed on top, they hardly withstand any pressure.
I have gone through quite a few testing cubes each with some setting altered, but nothing seemed to help.
It can't be the printers fault as I have successfully printed test cubes sliced with the old Cura in between (and not only once). Increasing temperature or slowing down the infill didn't help either. Neither did increasing flow rate or switching to triangular infill pattern. Also I have tried printing with all speeds set to 50mm/s and it still failed.
My standard settings (from which I have created many test cubes with each cube having some settings tweaked):
Layer Height: 0.12mm Init. Layer Height: 0.10mm Wall Line Count: 2 Top Layers: 6 Bottom Layers: 4 Infill Line distance: 5mm (used to be 20% in old Cura, but this is very dense in the new Cura) Infill Pattern: Lines Infill Overlap Percentage: 20% Printing Temperature: 200° Build Plate Temperature: 60° Retraction: Enabled, Distance: 2mm, Speed: 60mm/s Speeds: Print:60mm/s, Infill: 60mm/s, Outer Wall: 30mm/s, Inner Wall: 60mm/s, Top/Bottom: 40mm/s, Travel: 100mm/s, Initial Layer: 20mm/s Combing Mode: All
This problem is most commonly caused by infill speeds which are too high.
Instead of printing lines, the filament is caught on one of the lines of the previous layer, leaves a blob there and only restarts extrusion when it hits the next line. Instead of extruding continuously the filament comes out in blobs at the locations where there's filament on the previous layer.
You can have good infill up to some layer and suddenly start getting this problem as of some layer. When the problem occurs the next layer is more likely to show the problem. It's snowballing.