UM3: is this underextrusion?

[paoletto 3]

So extruder settings are the same (cloned with Duplicate plugin in cura), filament is also the same (just different color). Right is extruder one, gold, and left is extrude two, orange.
What could be the problem? Fucked up printcore?
Last print i did i was looking at it while printing, and it seemed that things were good until the top layer. also, bottom layers are perfect.
I performed the cleaning procedure with hot/cold pulls very recently. as far as i remember this extruder always had this problem.

Edited April 8, 2021 by paoletto

[Carla_Birch 116]

Thats underextrusion yes, does the same filament print fine with the same settings if you use another AA core? If so i would say that the AA core might need to run a clean on it a few times as it could be its got something really burnt and stuck to the inside, do you use the cleaning filament or pla? i find the ultimaker cleaning filament to be much better at giving a deep clean.

 

It's also a good idea to make sure the outside of the nozzle is clean also.

[paoletto 3]

Thanks for the reply, yes i cleaned using PLA, and i in fact cleaned the outside of the nozzle with a blade (!), and it took me a while.. (i was planning to use a brass brush but couldnt find any quickly) I was planning to switch cores and test the other core with this filament/feeder. Will try that and report!

Edited April 8, 2021 by paoletto

[paoletto 3]

So this is what my printcores look like: the underextruding one is the one that seem a lot more consumed on the bottom

[paoletto 3]

So swapping cores seem to have solved it..
I guess i shall try to replace the nozzle before thrashing that right PC..

[Carla_Birch 116]

19 hours ago, paoletto said:

So swapping cores seem to have solved it..
I guess i shall try to replace the nozzle before thrashing that right PC..

You can replace the nozzle itself in the printcore, but it does come with the risk of breaking the printcore if you are not careful.

https://www.3djake.uk/micro-swiss/coated-nozzle-for-ultimaker-3?sai=6115

[paoletto 3]

Thanks for the link, i have indeed ordered one of those, and will follow mighty gr5 instructions to try replacing it. I will probably attempt a cleaning procedure before.
I wonder: what's the use of that red o-ring that is also in the pictures of the micro-swiss product?

[UlrichC-DE 109]

The red rings used to be delivered with the Ultimaker print heads.
In the meantime, this is no longer the case.
It was supposed to protect the print head from filling up.
But the ring is unnecessary, as it turned out.

 

More text about it:
https://support.ultimaker.com/hc/en-us/articles/360012099819-Remove-the-print-core-nozzle-ring

 

[paoletto 3]

so i managed to replace the nozzle without screwing the heatbreak.
It was somehow tight to put it back in, i had to use definitely more force than gr5 showed on the video, but i suppose a new aftermarket nozzle might just be different enough to fit slightly different in the thread.
In any case, it seems to print alright now, and the procedure is delicate but not too tragic imo. Worth trying if a nozzle is fucked up.

[JohnInOttawa 104]

If it doesn't leak and you get autolevel to calibrate then you're good to go.

 

WRT increased torque to set the new nozzle.  A few things that I found really reduced the torque for my MicroSwiss install.

 

1) when the old nozzle is removed, carefully clean the threads inside the heat break and heat block as thoroughly as possible. Also, the very top of the nozzle seats against an internal brass lip in the heat break.  Cleaning that as well  will also help make a better seal.

 

2) If you reassemble in two stages, you can first freeze the nozzle and warm the heat block, then thread the nozzle into the heat block until it is tight.  Once they are together, freeze that assembly and heat up the heat break before the final joining.  That will reduce the torque and give the best chance at seating the nozzle all the way, as it is much easier to feel when the nozzle 'bottoms out' in the heat break.

 

But like I said, if you aren't leaking and getting things to level, then it has all worked out fine for you.

 

J

[paoletto 3]

Thanks for the suggestion of using heat to ease the process.
I'm not sure, though, how to first tighten the heat block. I have left it loose until the very end, because i had to plug the wires before the process, or i couldn't fit them in anymore.
So essentially i screwed the nozzle in the heat block just enough so that the heat block would still sit close to the heat break, plugged the wires, then started to screw the nozzle further, while keeping the heat block aligned.
At the end i tighten the heat block.

Edited May 2, 2021 by paoletto

[JohnInOttawa 104]

Yes it is an interesting setup on the heat block and nozzle.  Normally when a machine screw joins two parts, the first part is not threaded, just the 'destination' part, so the screw pulls the parts together and doesn't end up jacking them apart.

 

The Ultimaker design with threads in both the heat block and the heat break requires that the heat block be fully threaded onto the nozzle first (fully torqued), which effectively makes that one assembly.  Then the heat break can be threaded on in a single assembly step without fear of the two parts working against one another.  This can be done with the parts in the print core frame and before the top level and 'trumpet' are reattached.

 

Your note on the heater and sensor wired reminded me, I have a very wordy post that describes my voyage through nozzle replacement including dealing with those stiff wires.  If you have trouble sleeping tonight, I suggest you read that post.  It ought to do the trick 😉

 

Stay well! 

 

John