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Yet another blob and stringing problem SOLVED


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Posted (edited) · Yet another blob and stringing problem SOLVED

Hi there,

Update: solutions are in the end of this post

Currently I am experiencing blobs and even some serious stringing, specifically when using High quality settings on Cura 15.04.2.

I have been browsing forum for a while and experimenting with different retraction, print speed settings, lowering temperature, yet I did not manage to find solution.

Regarding blobs - they form where nozzle approaches new printing perimeter.

I am using Ultimaker PLA gray and bronze.

Printer is in mint condition, no mechanical problems.

Retraction works fine.

In the last photos (with bronze bracelet) I'm using freshly installed Olsson Block.

Here are the photos:

https://www.dropbox.com/s/9o6zzivh7n1p1he/DSC_0329.JPG?dl=0

https://www.dropbox.com/sc/x83brwaht2wz1gv/AACCyMvjiAIH4T_S4ObJQoq-a

https://www.dropbox.com/sc/vrtgte07z0lgrvt/AAB4WWiatzAJHT6YjMIdD52da

 

Solutions

Retraction did not work because I really had two problems with printer and I think this might be interesting to others.

1. After head reassembly I did not fully push bowden tube down to "slot" inside teflon coupler, the filament started grinding one side of the coupler, creating groove and thus causing more friction near nozzle. When motor wants to retract, filament is not aligned 100% to nozzle as a result friction prevents it from successfully retracting.

Had to replace teflon coupler, because even after correct reassembly and rotation of teflon coupler retraction did not work correctly.

2. When I assembling Olsson Block, I obeyed recommendations and did not fully tightened the Stainless steel coupler down to Olsson Block and left about 1 mm gap. That was mistake, I only needed to leave very tiny gap between coupler and block. (I do not want to go into details explaining why it created difficulties for retraction, You may realize by yourselves.

When I corrected these two problems, printer works perfectly.

Edited by Guest
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    Posted (edited) · Yet another blob and stringing problem SOLVED

    Print temp?

    Speed?

    Travel Speed?

    Retraction length?

    Layer height?

    Listing quite a few specs kinda helps. Or screen shots or cura settings.

     

    Excuse me for not being explicit.

     

    • I'm using Cura preset "High quality" (speed 50, travel 150, height 0.06)

      Tried increasing while printing 130% speed, nozzle started bumping into these blobs.

       

    • Temp 210. Tried lowering to 200, 195, with no success.

    • Retraction settings are default (firmware). I guess it was 4.5mm @ 25mm/s. Tried increasing it even to 5.5@45mm without no success.

     

    My observation is that while nozzle is leaving one print perimeter there is small deposit of plastic. And when it goes to the next perimeter, this small blob is being on the edge of the next perimeter.

    Attached Cura settings

    Edited by Guest
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    Posted · Yet another blob and stringing problem SOLVED

    Those blobs are from oozing as its traveling and is a form of stringing

    you can go through this article HERE

    Lower layer heights extrude the plastic a lot slower then higher layers. So the plastic has more time to heat up and therefore expands more. Some filament is worse then others.

    This means that you can print a lot cooler.

    You may have a bad roll as Ultimaker has had a bad batch go through or you may just need to test you printers limits. Some printers have a temp sensor that out a little.

    Printing two towers like in the article is a good way to learn what works best and uses only a small amount of material to test.

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    Posted (edited) · Yet another blob and stringing problem SOLVED

    Those blobs are from oozing as its traveling and is a form of stringing

    you can go through this article HERE

    Lower layer heights extrude the plastic a lot slower then higher layers. So the plastic has more time to heat up and therefore expands more. Some filament is worse then others.

    This means that you can print a lot cooler.

    You may have a bad roll as Ultimaker has had a bad batch go through or you may just need to test you printers limits. Some printers have a temp sensor that out a little.

    Printing two towers like in the article is a good way to learn what works best and uses only a small amount of material to test.

     

    I measured nozzle temperature with tester and readings are nearly the same ( diff -2C on tester, but that's probably because I hold it by hand against nozzle)

    Currently I'm investigating other similar threads in forum. I will update this thread when I find solution.

    Retraction settings - default. Retraction is working. Bowden tube stays tight.

    Nozzle - Olsson block (but it was same with original nozzle)

    Filament - Ultimaker Gray PLA

    Cura 15.04.3

    And I have done a few tests.

    One prepared GCODE from Ultimaker 2 temperature torture test

    TEST_PLA_TEMP_NP_2H01.gcode

    5a33147211d02_Torturetest.thumb.jpg.b1304163a88f2b787aa6387bc584b132.jpg

    Another I prepared myself with Cura + Tweak@Z

    While printing these on normal, occasionally I heard nozzle bumping into print.

    5a331473072d0_Towerstest.thumb.jpg.f95d81c4a1e070835c9e961df61fc4b4.jpg

    5a33147211d02_Torturetest.thumb.jpg.b1304163a88f2b787aa6387bc584b132.jpg

    5a331473072d0_Towerstest.thumb.jpg.f95d81c4a1e070835c9e961df61fc4b4.jpg

    Edited by Guest
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    Posted · Yet another blob and stringing problem SOLVED

    Updated - found the solutions for my problems

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    Posted · Yet another blob and stringing problem SOLVED

    Would you share the details? I also have similar issues from time to time.

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    Posted (edited) · Yet another blob and stringing problem SOLVED

    Would you share the details? I also have similar issues from time to time.

     

    I posted details in the original post. In the essence - carefully check head assembly - check nozzle, stainless steel/Teflon couplers and bowden tube (e.g. does it fit tightly Teflon coupler). There might be too much spacing in the assembly or parts may be misaligned. All of that create unnecessary friction.

    Edited by Guest
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