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aubustou

Filament jammed in print core

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Hello,

 

I bought an Ultimaker 3 one month ago and I have a constant problem of jamming/gindring in Printcore AA with PLA. All 2 hour long prints are half done because of this.

Actually, the filament is stuck because of an increase in diameter from 2.85mm to 3mm around the Printcore. Friction in boden tube, retraction prevented, grinding in the feeder, filament jammed.

 

That makes me quite astonished because I haven't changed anything in the Cura profile, nor on the printer. I never had a problem like this on Ultimaker 2+...

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The increase in diameter happens to me also but it's not a problem for me.  I can still print just fine.  Is your "third fan" working?  The one in the door of the UM3 print head?

 

You should have gotten a second AA core.  Have you tried that to see if there is something wrong with your core?

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Quote

The increase in diameter happens to me also but it's not a problem for me.  I can still print just fine.  Is your "third fan" working?  The one in the door of the UM3 print head?

 

Yes, it is working.

I suspect the diameter because when I remove the boden tube, the filament gets stuck precisely when I try to push in the thicker part.

 

I'll try with the provided second AA core. Thanks for the tip. Launching a print and getting back to you.

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There's tons of causes of grinding of filament back at the feeder but this one - filament grows to 3mm - is not something I've heard of much before.  Are you sure that's the issue?  how do you know?  when it happens is the filament stuck in the core?  Can it slide up and out?

 

This growth in filament size may be unrelated is what I'm trying to say.  There are about 15 causes of failed extrusion on my list but not this cause as I've only seen it be a problem when the print is over.  Maybe we should look into other issues?  maybe I should give you the complete list?

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Hi,

sorry, because of my humble English ...
This thickening happens in every Hotend. Without this, a retract would be largely ineffective ... (In principle, like a syringe: there is a hole at the bottom, but at the top it is sealed by a moving piston - here filament -)
Otherwise, once liquefied, it would immediately run out of the nozzle unrestrained.
But the important thing is that it happens in the right place! Here's it, right at
Metallhotends, a big risk if too often in quick succession too much material
is pulled back. Thus, the temperature moves with the excess material across the temperature barrier into the cool zone - which is fatal. There, this thickened material can no longer be transported into the hot zone, because too cool and filament is too thick. It is then stuck and can only be pulled out.
Something is also conceivable, if the fan for the Hotendkühlung not enough cooling air at the Hotend can pass (Dirty, Eingehaust and too high temperature, or generally too high ambient temperature - PLA is very soft even at very low temperatures). It can not be a malfunctioning Hotenendlüfter, since the problem does not occur after 2 hours or so, but within minutes (after 3-4 minutes, the temperature is already more than critical ...).
I would guess. I hope you understand somewhat what I mean ..

Greetings, Digibike

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Yes, I understood quite a bit. The filament is thick over a large distance along it, around 5cm starting from the hot end. I never had this problem for over a year on an Ultimaker 2+.

 

Well my Ultimaker 3 is brand new. I bought it in past May. Therefore, I don't think it's a lack of maintenance because I used it less than 5 hours.

 

I definitely think there is a problem with cooling in the hotend, but the fans are working correctly...

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12 hours ago, aubustou said:

Yes, I understood quite a bit. The filament is thick over a large distance along it, around 5cm starting from the hot end. I never had this problem for over a year on an Ultimaker 2+.

 

Well my Ultimaker 3 is brand new. I bought it in past May. Therefore, I don't think it's a lack of maintenance because I used it less than 5 hours.

 

I definitely think there is a problem with cooling in the hotend, but the fans are working correctly...

Did you also check the third fan, the little one at the back of the nozzle? Your description of phenomena is exactly what happens when this fan fails: heat traveling way too far up into the filament, and softening this before the nozzle, so it can't get into the nozzle anymore. Maybe some piece of plastic got stuck into the fan? Or a loose electrical wire?

 

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On 6/7/2018 at 1:58 PM, geert_2 said:

Did you also check the third fan, the little one at the back of the nozzle? Your description of phenomena is exactly what happens when this fan fails: heat traveling way too far up into the filament, and softening this before the nozzle, so it can't get into the nozzle anymore. Maybe some piece of plastic got stuck into the fan? Or a loose electrical wire?

 

 

The little one at the back of the nozzle? Err, what fan at the back of the nozzle? There is one in the Ultimaker 2 but not on the 3...

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5 hours ago, aubustou said:

 

The little one at the back of the nozzle? Err, what fan at the back of the nozzle? There is one in the Ultimaker 2 but not on the 3...

 

The equivalent fan on your UM3 is the front fan. It should keep the upper part of the print core from getting too hot. If filament hairs get tangled in it, it could stop running.

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6 hours ago, fbrc8-erin said:

 

The equivalent fan on your UM3 is the front fan. It should keep the upper part of the print core from getting too hot. If filament hairs get tangled in it, it could stop running.

Ah okay. I don't have an UM3, so I didn't know that fan has changed location. In my UM2 I once found that it had sucked up filament hairs: it looked like a coloured PLA spider web, although not enough to stop the fan yet. The bearings of these little fans also tend to wear out fast, much faster than bearings of big fans. First they get noisy and slow down, they wobble visibly, and then they totally stop due to too much friction in the damaged bearings. This was a very common problem in early Pentium computers (1995...2000). This could also happen if dust from clothes accumulated in the fan bearings, or inbetween the blades. So it is something I still look out for, if overheating might be one of the causes of a problem (but of course, there could also be other causes).

 

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Ok, I understood what happened. I forgot to mention one major point: I bought a Box3D enclosure along the UM3.

I wasn't sure about the electric fan so I haven't plugged it. The sound reduction was great for me and I didn't see the problem with temperature.

Turning on the electric fan on the enclosure solved the problem.

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