Extruder problem

Hi folks, I've come here with a printer issue, just like many
I was adjusting and configuring my first printer, and as it goes, I've encountered a Problem First layers machine prints very good and precise. No gaps, no missed parts, holes etc. I would say they are as good as one could expect from my printer.
The picture changes dramatically after some ten minutes of printing. It looks as if extruder runs out of filament. Extruder's gear is turning like normal, but nothing coming out. Then it goes okay for some minutes. Then again - no filament. The further go, the worse printing becomes. Please, have a look at the attached photo.

I would thought that extruder is clogged, but I never changed filament yet, and never put there anything except filament.

What would you advice?

First need to know: Material, temperature, type of hotend, does it have a fan, type of extruder.

Sounds like you are using a metal hotend without a fan cooling it.

You need cooling turned on in your slicer. It will slow down the print when a layer takes less than a certain time. This allows the filament to cool a little and not just blob up.

Sure, pla, 185/65, simple metal hotend 0.5. Extruder is from plastic, for 3mm filament. Fan is present. Printing speed is 30mm/s.
I've just tried printing big part, and found it seems connected issue. Filament flow seems very irregular. Please, have a look at the printed first layer (or rather raft, but that shouldn't matter).
To me it looks as if I should through out my plastic extruder, and buy a good one, from metal, and for 1.8mm filament...
I have tried to increase temperature up to 195, tried in increase flow factor. To no avail. Any ideas?

Can you post a picture of your extruder and hotend assembly? I don't think the problem is the extruder. When you mention a fan present you mean for the hotend or for the part been printed?

Maybe obvious, but it's happened to me... Is your filament feeding OK? Nothing jamming up the spool? No tangles in the filament? Is there enough pressure pushing the filament against the extruder gear?