Under-Extrusion? Salmon Skin?  

Under-Extrusion? Salmon Skin?

Hi all,

Been printing in the last 2 weeks some miniature wargaming tanks. I bought a 0.25mm nozzle especially for this and the mk4 was giving me fantastic results. First 2 weeks went very well. Printing time per 15mm tank takes about 3 hours, 0.05mm layers and pretty low speeds; I'm a patient man. Filament used is dried Polymaker Polyterra PLA @195°C.

Speeds used are the following. Maybe the infill is still a bit high but okay, it's not that the tanks will be trown around by the Hulk.

couple days ago, I started getting this weird texture on my overhangs but only on one side of the print; looked everywhere and most common would be the 'salmon skin' problem, the other thing I noticed is the top layer is full of holes, that looks like under-extrusion.

Things i already tried:

• 3 cold pulls, nozzle looks fine. - No improvement
• tried 205°C, 215°C and 220°C.- No improvement
• lowered the speeds even more, all down to 20mm/s. - No improvement
• checked belt -tension. The were a little losse but still very much ok. - No improvement
• checked all the parts for loose screws. - No improvement
• checked both of the nozzle-screws but nozzle was tight. No movement whatsoever. - No improvement
• went to layer height of 0.1mm (picture below, right one) - Salmon skin gone
• trying another brand of filemant now (currently printing) - currently running

Printer is on a isolated concrete slab on a fixed table. Filemant is dried and in a closed box. Nozzle is only been used with about 300-400gr. filament in total. Could it already be worn out??

I'm just baffled by the fact thats it's been running 2 weeks non-stop with fantastic results and all the sudden, no chenge in settings, it started doing this...

Maybe someone has had the same problems and can already share some information. Many thanks already!

left tank & middle tank : 0.05mm layer height 195°C

right one is 0.1mm layer height and 195°C

The salmon skin?: