Extrusion stops during first layers when printing large objects

[fade 1]

Hey,

I have the following problem and I really don't know what to do now. My ultimaker 2+ prints without any issues when printing small objects. However when printing a larger object with a big base area the nozzle just stops extruding after approx. 10-15 min (which is usually during the first layer or the beginning of the second; see picture). When this happens I have to remove the filamet as it is continously fed into the nozzle, then gets bulged (see picture) and in the worst case cools down inside the tube (and you will never get it out of the tube again).

The thing that makes me wonder the most is that I have no problems with smaller objects when using the exact same settings.

My settings are:

 

• Voltivo Excelfil Transparent PLA 2.85mm
  
• Temp: 210C (I've tried 230, but same problems)
  
• Layerheight: .1
  
• Initial Layer: .27
  
• Line width: .35
  
• Print Speed: 50
  
• Top/Bottom Speed: 20
  
• Top/Bottom thickness: .8
  

 

I appreciate any help guys. All my larger objects are waiting :-).

Cheers,

fade

[SandervG 1,357]

Hi @Fade,

Thank you for your message, lets see if we can move any closer to the origin of your issue

Do you also have a photo of one of your successful prints?

Do you have some more information on why your filament stops extruding? I understand this is part of your question too, but do you know if it starts grinding at the feeder? Can you manually pull out the filament from your feeder when it has stopped extruding without using the lever? Is there a lump at the end of your filament? Is your nozzle clogged?

You say it stops extruding, but also that you have to remove the filament cause it keeps being fed into the nozzle. Well, it has to go somewhere, it doesn't disappear Looking forward if you can shine some light on anything that behaves out of the ordinary when your print stops.

Thank you!

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Hi SandervG,

thank you for your fast reply :-). Please see the picture for a succesful print and I also attached another picture of a bulgy filament end.

As far as I understand this problem, at some point the filament does not exit the nozzle anymore and the feeder keeps on feeding. Then the lump starts to grow inside the extruder until it becomes too big and the feeder starts grinding into the filament.

I have no idea why the extrusion stops after printing without any issues for a while. Very odd is also that after the problem occured, I perform the change material process (which means I remove the filament, cut off a bit and insert the same filament) the extrusion works just fine and I can start the next print (then, if it is a smaller one it prints without a problem).

I calibrated the bed, did the atomic method several times and cleaned the bowden tube.

Looking forward to your reply.

[geert_2 432]

The heat seems to travel unusually far up in the filament? Have you verified if the little fan at the back of the nozzle is working while printing?

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Hi geert_2,

thanks for the hint. It seems like it is not working. I read about this issue a couple of times before, which makes me wonder why the fan isnt working for so many people. Other than that I am not sure why this problem only appears when printing large base layers.

Anyways...I will fix the back fan and keep you updated if my problem is solved with that.

[IRobertI 468]

On large prints your head stays close to the hot bed for a longer time which makes the issue worse, that's why you're seeing it more on large prints.

I'm sure it will be solved with a new/fixed fan. Make sure the fan is actually broken and that it's not just a wire that is pushing into the blades (or a stray piece of plastic).

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Hi IRobertI & geert_2

thanks for your hints. It really was the back fan, the prints are just fine now.

The connector J34, to which the fan is usually connected does not deliver any voltage when measuring. So after a little forum search I reconnected the fan to J22, which also delivers 5V.

Thanks so much for your help guys.

PS: There also was a stray piece of plastic in the fan ;-)