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Underextrusion problem ... again

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Hello and sorry for starting a new topic about underextrusion.

My underextrusion problems appear on parts of the model where the printer is using retraction and when its coming back. Every wall is after retraction is underextruded.

The next underextrusion problem when the printer starts the walls of a new layer, every start of a new layer is underextruded....

Take a look at the pictures please:





As you see the other part of the model is really nice.

What can i do for this problem?

PS: z-hop was enabled with 0.075

LH was 1mm and 1.5 mm, temp was 210-230, speed was 50mm(1-2 pic) and 25mm/s(3-4 pic)

Thanks in advance.


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Ok a couple of questions first. What is "LH"? Is it layer height? If so then that is at least part of your problem. I have never heard of anyone printing with1.0mm thickness let alone 1.5mm. I wonder if it is possible.

What shell thickness are you using?

What is your retraction speed and distance?

In your 1st pic you seem to be saying that at some heights the new layer is being started on an inner wall and at other heights it is starting on the outside wall. What did you configure to make that happen?

In pic 2 are you using the same layer height below and above the hole; they look different to me.

If you have two windows close to each other then in my experience the short run between the two windows can be quite difficult to get printed nicely. Best done at 20mm/s, definitely not 50mm/s.

I would suggest you try again with LH of 0.3mm, speed of 20mm/s and temp maybe 210 although I am assuming that is UM blue filament which I have not used.


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Hello sir, thanks for the fast answer and sorry for my slow answer, i wasnt available last days....

ok, LH is layer height, but instead 0.1 mm and 0.15 mm i accidently wrote 1 and 1.5. shell thickness is always around 0.4 mm.

Retraction speed? huh, didnt even know that i can adjust it, it's just by me at the default retraction checkbox enabled. I found your options in the expert mode and they are the default too, 1.5 mm minimum, 0.02 min extrusion, combing enabled.

At 1st pic, i didnt configure anything, cura sliced it that way (but it had not a lot infill and the new layer didnt started every time at same point). Sorry if i wrote it wrong, some heights are starting on the other side of the model, not really inside.

In pic 2, again i dont know that i can even print a model with different layer heights, at same time. But, its the same layer height, i currently dont remember, but maybe i rised a bit the temperature, that could be the reason for the different heights.

I just noticed that the printer after retraction need some time to extrude the same amount like before retraction, you can see at pic 3 that the whole wall is underextruded. The house model is printed at 25 mm/s.

Sorry, but my english is not great :)



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I would double the shell thickness, 0.4mm is not enough for me.

You can change the retraction settings in the tune menu on the UM2 (or for the material).

How old is you UM2? Has it printed a lot? If you have trouble with retractions you might need to check your teflon (if it's deformed it will struggle more with retractions)


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It's not really old, 1.5 month already, still didn't printed out the first filament. I will try it with bigger shell thickness.

I dont know if this is a big problem for the quality, but i have the filament grinding problem since the first print. I updated the firmware but nothing changed.





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It's not really grinded (grinding means that the filament is really damaged), maybe you can reduce the pressure of the feeder a bit with the white 'buttons' on the feeder, but i don't see that as a problem.

After 1.5 months your teflon should be still very good

If you need to test on your specific model you can use cut off bottom in Cura so that you don't need to print the part that doesn't show problems


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