Problems with clogged Nozzle  

Problems with clogged Nozzle

Hi

I bought 3 Prusa Mini, with 2 I have problems.

In the case of the two mentioned, the printing temperature has to be raised significantly, otherwise the nozzle clogs and the extruder grates the material.

I have to print PLA with 230 degrees, if I lower the temperature  the nozzle gets clogged.

I tried 5 different materials, including the material samples from Prusa.

I opened the extruder and checked for contamination, checked the Bowden cable for resistance, checked the PTFE tube in the hot end, pressed material through the hot end by hand (went very easily),I´ve also done a cold pull…..  everything looks OK

This is how the problem is expressed

When I load new material (PLA) into the printer, I preheat the printer to PLA (215 °).

The material runs through the hotend without any problems and comes from the nozzle.

If I now start printing, the printer cools the nozzle to 170 °, performs the meshbed leveling, and then heats up again to 215 °

if it then begins to print, the nozzle is usually directly blocked, possibly printing continues for a few minutes at the latest, then the nozzle is blocked. (First layer distance fits!)

After a short time it clicks from the extruder, the motor loses steps.

The preload of the ball bearing in the extruder has also been changed several times without success

But if I set the temperature to 230-235 ° after the meshbed leveling, the print runs through without any problems.

If I didn't know better I would say that the hotend is too cool. But that can not really be, because when loading the material with 215 ° it runs through the hotend without any problems.

As I have already written ,3 minis were bought, with 2s I have this problem, one works without any problems.

I own two more Prusas, an MK2.5s and an MK3S with MMU2, so I'm not a newcomer to 3D printers

Does anyone have comparable problems

Ps: Sorry for my bad english, google translator is my best friend