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mariem

grinding issue, filament stuck in printing head.

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Helloo guys!

Just a small question,

It's the second time I have a grinding issue

The first time I was able to easily fix it by removing the bowden tube, cutting the filament at both extremities and removing it.

This time I cut the filament once again after removing the bowden tube.

My current issue is, The filament seems to be stock in the printing head.

I tried heating the nozzle and pulling on the filament but I'm worried I might cause damage or something..

What am I suppose to do?

 

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If you heat the head, and remove the Bowden tube at the printhead end, then you should be able to just pull the filament out of the nozzle. The only place it could possibly have gotten stuck is if the white PTFE coupler has lifted up inside the isolator nut (the thing with holes in), and plastic has gotten under the PTFE part, but above the nozzle. Is your teflon sitting higher, or at an angle or anything?

In that case, you might want to unscrew the nozzle, and take the ptfe part out to clean things, remove the filament and reseat it. If not, then the filament should just pull out of the hot end.

 

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I'm really bad with all those terms, ptfe couple and stuf... isolator nut...

All I know, I did heat up the nozzle, I remove the bowden tube at the top and tried to pull the filament out.

I could see the white part inside (coupler) moving up I think when I was pulling, I was worried I might break something so I stopped there.

Is that suppose to move?

Do I have to pull really hard?

 

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Yes, the white part is the coupler. Isolator nut the thing it sits in.

It looks like you had some filament stuck either in, or under, the coupler. Just make sure that afterwards, the coupler has settled back down straight inside the isolator, so that there's about a 1mm gap between the top of the isolator and the wide part of the coupler.

 

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Just make sure that afterwards, the coupler has settled back down straight inside the isolator, so that there's about a 1mm gap between the top of the isolator and the wide part of the coupler.

 

So is there a problem if that 1mm gap isn't there? My PTFE couple sits flush against the top of the isolator. No gap, and I'm not able to force there to be a gap due to the spring.

I suppose I could wedge a 1mm piece of just about anything between the two parts, but that seems like it would be a very bad idea?

 

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You adjust the gap by rotating the nut. The nut is not a normal nut - it is round instead of hexagonal and it has 6(?) holes through it that you can use a tool on to rotate the nut. The purpose of the nut is to raise or lower the nozzle - this is important for dual extrusion to get both nozzles the exact same height within .01mm or so. However dual extrusion has never worked on UM2 so it's a feature not needed.

My impression is that the gap should be 1mm *or smaller*. This is to keep the spring from pushing too hard and deforming the isolator. Maybe there is another reason that I don't know about.

BE VERY CAREFUL WHEN ROTATING THE NUT. It is not strong - there are brass and/or copper parts involved which are soft and easily ripped. Only rotate when the nozzle is at 180C (because the PLA acts like a strong glue in the threads if not hot) and if you seem to be twisting with much force consider taking it apart enough so the spring is removed also. In fact it's easiest to rotate the nut by sticking a thin screwdriver through two opposite holes which you can only do if you remove the white isolator first. Although this design is meant to be rotated with the head assembled so you can "level the 2 nozzles".

 

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Yes, the gap should only be created by the positioning of the threaded part of the nozzle block inside the isolator nut. The white ptfe part should always sit directly on top of the brass part, inside the isolator. If it isn't all the way down inside, then you end up with a gap between the two that plastic can expand into resulting in leaks and clogs. However as you screw the nozzle block up and down inside the isolator nut, then you are also adjusting the level of the ptfe coupler on top of the nozzle piece, and hence the gap visible above the isolator nut.

If the visible gap is too large that means the nozzle is quite high up compared to the base of the fan shroud, making it more likely that stray plastic will curl up behind the shroud, form a mass around the heating block.

If the gap is too small, then the block can get pushed down against the fan shroud, forming a heatsink that can make it hard to maintain proper extrusion temperatures evenly in the nozzle.

 

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