Material gets stuck in tube - solved

[oskarq 0]

I can't get my UM2 to print properly. The material gets stuck in the lower part of the tube after a couple of minutes.

 

I would imagine this to be caused by the temperature beeing to high together with a slow speed but I have followed other peoples settings where they have gotten good results. The printer is located in a quite small room that can get pretty hot sometimes, could this be a part of the problem?

 

Printspeed: 40mm/s

Temp: 190°C

layerheight: 0.2mm

 

 

[IRobertI 520]

First thing to check, is your third fan running? There's three fans on the head, one on each side and one at the back of the head. The one towards the back should turn on and stay on as soon as the printer is turned on.

 

[DidierKlein 729]

Isn't 190°c a bit low?

Try raising the temperature to at least 210°c... some say 230°c is a good temp too.

 

[gr5 2,172]

The material gets stuck in the lower part of the tube

 

The end near the feeder or the end near the print head?

If "print head" then definitely make sure that 3rd rear fan is working. It's on the print head - not the side 2 fans - the 3rd one in the back. It should come on as soon as you power on - even before the lights come on.

If it doesn't work, slide up the black mesh until you expose all the wires and connectors - the 3 fan connectors are black/red wire pairs. This area of the printer fails for many people during shipping - I don't know why. Two of the connectors are connected together with a short 50mm wire - those are the side fans. Tug and push on the wiring to the 3rd fan. Also if it still doesn't work, remove the larger cover under the machine - only 2 screws hold it on.

 

[illuminarti 18]

The point where it is getting stuck looks to be around where the clips hold the tube in place, so it's possible that there is a tiny constriction there due to the clip.

Also, your second photo shows a huge amount of chewed up plastic in the extruder driver housing. That shouldn't really be happening on a UM2 - the motor should be skipping rather than chewing up the plastic like that.

It could be related to the heating/fans, as suggested above, but I'm also wondering if you are simply chewing up the filament so much that it has physical damage that won't fit through the tightest part of the Bowden. Whenever you get under-extrusion and any sign of the filament getting chewed up, you need to remove the filament and cut off the damaged part.

If you remove the filament from the tube, what does the stuck part look like?

 

[jonnybischof 60]

Isn't 190°c a bit low?

Try raising the temperature to at least 210°c... some say 230°c is a good temp too.

 

That depends on the type of filament...

The UM blue should print perfectly fine at 210°C or lower. I'm using 200°C at the moment with UM blue, but I extrude much slower (40mm/s with 0.1mm layer height -> half the extrusion rate!), so I'd guess 210°C could be ideal for you.

/edit:

Bed temperature also matters. For me, 60°C works well with UM blue.

 

[oskarq 0]

Thanks you all for the insights and tips. The fan in the back was not spinning at all. After a little trouble shooting I found out that the reason for this was because the connector attaching to the arduino board was intalled the wrong way :mad: . After I flipped the connector the fan started to spin (for the first time...). Hopefully it will now work a lot better.

Regarding the chewed up material in the back. What can I do about this?

 

[illuminarti 18]

The chewing may stop, now the fan is working better.

Just watch for it happening, and remove the filament, and cut off any damage when it does happen. Clean out the extruder assembly of dust as best you can - canned air will probably help with that.

 

[IRobertI 520]

Now that the fan is running as it should that grinding you saw will hopefully go away as the filament will no longer get stuck. Before you start printing again clean out that mess. Pay special attention to the knurled bolt in the center and make sure there isn't a bunch of plastic in the knurls as that will make it harder for it to grip the plastic.

 

[oskarq 0]

No more getting stuck in the tube and grinding of material =D. Finally I can start printing things with quality and reproduce the results. Thanks for all the help!