The nozzle becomes clogged in the smoothing mode

Question

My nozzle gets clogged when it starts to do smoothing. Settings below:

Answer 1

The filament conducts heat (not much, but it does), so the heat from the hotend travels backwards towards the cold part. Usually the filament during print moves forward faster than the heat travels backwards, so there is always fresh, cool filament on the back.

In your case, since you move filament 12% of the normal speed (which is not fast already in an Ender 3), the forward motion of the filament is too slow and the heat travelling back softens the filament (50 °C are enough) and it clogs.

The solution is to use Polymaker PLA, which is not cheap, but it has been treated to completely avoid this issue, since it doesn't soften at 50 °C but at 100 °C so that even when printing slow it will hold up.