Putting some canola oil onto the PLA filament to keep it from jamming, aka "KLUNK! KLUNK!".
And it works REALLY well.
I use the software-temp-mod on my Mini plus two extra fans on the extruder-stepper.
That already helped, but it was always close to stalling, even with high-end filament.
The reason for the jamming seems to be that the warm filament tends to stick to the inside of the steel-tube between motor and nozzle.
That's why the cheap, uneven/bendy PLA tends to stall significantly more often than the straight premium stuff.
So testing with a drop of oil on some tissue and rubbing a thin layer onto the filament worked great, I could not believe it!
Next step was to make an oiler to put into my filament's path.
It has pretty thick walls so it doesn't leak and the two openings have high internal walls, so the holes don't ooze either.
I sealed the insides with some 2K 5min. acrylate glue and put in a piece of plastic sponge.
Make sure to cut the sponge to the correct size and then punch a straight hole from hole to hole so inserting the filament dosen't get frustrating.
The put in some oil (not too much for now) and give it a go!
To keep the oiler from moving along with the filament I added a little ring to just tie it to my filament-container.
And I also made a smaller version that I only put a piece of dry sponge in to collect excess oil.
The printing process got a bit more smelly - namely the scent of popcorn
And I noticed that when you change filament or start printing after full cooldown, you sometimes get a small drop / smear of oil with the first line, but after that it all works fine.
Here are the STL-files.
https://dl.dropboxusercontent.com/u/128 ... _Oiler.zip
Print in 0,3mm layer / full infill / normal speed / thin wall option (worked for me and the lid fits perfectly).
https://dl.dropboxusercontent.com/u/128 ... _Oiler.png
https://dl.dropboxusercontent.com/u/128 ... er_Lid.png
https://dl.dropboxusercontent.com/u/128 ... _small.png
A friend has a Mini too and prints fine with a roll of filament that does not print right at all on my Mini.
I guess it's fair to assume quite a spread in tendency to CLUNK! amongst the printers.
So far I found that the motor seems not to be the issue, but the driver.
It seems to stall at a current too low to deliver sufficient force and I guess that there might be spread in the fine-tuning of the current-limit, namely a small trimmer-pot those drivers usually employ.
I haven't looked under the drivers' coolers, would be interesting to know which exact driver is on there…
Many times I've used 3rd party PLA with my UP MINI and have had to spend an hour cleaning out an extruder jam with a drill.
Tried your solution. Doesn't seem to work at all for me, though that may just be the filament - I'm testing filaform PLA.