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Bad results on front side of a PLA print only


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Posted · Bad results on front side of a PLA print only

Hi!
 

Any clues why the BACK of the print looks near awesome but the FRONT looks like CRAP?? (sides look ok too). PLA print on UM2E+ with latest official firmware and olson Ruby nozzle 0.4 printing at 50mm/s.

(Yes, I've checked the STL for manifold errros and the Gcode and both look fine)

The printer has an enclosure installed but I printed this with the door open and the ambient temperature is currently low, like 16-18ºC and since the rear part was printed fine, I don't think it's about too much heat, plus the PLA i'm using has a higher melting point than regular PLA...

20190326_094505.jpg

20190326_094456.jpg

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    Posted · Bad results on front side of a PLA print only

    They look about the same to me.  I think the difference is the angle of the light.  This is a shiny black filament which has the greatest contrast between reflected light (white) and background color (black).

     

    If you printed this in a matte filament (these are very rare) or if you printed it in white, it would look a lot better.  Because it is shiny black, tiny changes in the *angle* of the surface - ripples - stand out and are easily seen (but not easily felt or measured).  If this is a work of art I would recommend spray painting it with a gray primer and it will look 10X better.  Then you could paint it with a flat black paint if you really want black.

     

     

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    Posted · Bad results on front side of a PLA print only

    To reduce the ripples, the simplest solution is to set all the printing speeds the same and to slow it down to say 25mm/sec.

     

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    Posted · Bad results on front side of a PLA print only

    THey're DEFINETLY not the same finish and DEFINETLY nothing to do with the light angle hehe, you can feel the bad finish by just looking at it when on hand but of course also by sliding the finger or the nail over it....

     

    25mm/s sounds ridiculously slow, I set 50mm/s for overall speed but the outline, ie outmost permiter is at 60% of that, so it's even slower, so if the back wall is printed nice, I can't understand why the "front" comes so ugly! Let me take a closeup pic for you, without light "angles"...

     

     

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    Posted · Bad results on front side of a PLA print only

    In the first picture at the right side where it's most "crunchy" is that where your seam is? because it might look like it's you acceleration thats way to high at the beginning of each layer.

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    Posted · Bad results on front side of a PLA print only

    If it's the acceleration then it's the "stock" setting of the firmware/machine....it should happen to everyone :??

     

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    Posted · Bad results on front side of a PLA print only

    I am literally having the exact same problem as you. My post is a few down from here. 

     

    The solution that was offered to me is that the infill was printed too fast. 

     

    I have the issue with petg @ 50mm/s and pla @ 80mm/s. Unfortunately, I haven't had a chance to test. 

     

    Good luck! 

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    Posted · Bad results on front side of a PLA print only

    It's true that I have set the infill at 100% speed and that is 50mm/s but I dont' find it that fast. However I don't find that as an explanation as to why this would affect only the frontal wall considering there are 3 more walls, left right and rear, and frontal is the only one affected. Makes no sense to me :? PLus i'm using only 15% infill in that area. 

    Below that area, I was getting better results on a 80% infill, same print, just lower height. And the print was firmly stuck to the plate, although it's also true i've been complaining of bed rattling too much at 70mm/s prints, I thought 50mm/s would be OK....

     

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    Posted · Bad results on front side of a PLA print only

    (but hey, yours not even an Ultimaker! 😮 :))

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    Posted · Bad results on front side of a PLA print only
    17 minutes ago, bolsoncerrado said:

    However I don't find that as an explanation as to why this would affect only the frontal wall considering there are 3 more walls, left right and rear, and frontal is the only one affected. Makes no sense to me :?

     

    I'm not sure what effects if the print goes clock wise or caunter clock wise!


    But if it starts at the front left corner and moves caunter clock wise, the front side will be your starts surface, and if the speed or acceleration is to hige the surface will be effected and not neseserly the rest of them. 

     

    Your print looks tall and narrow. so the higer up you go the more sencetive it will be to changes in speed. and cause z-scaring.

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    Posted · Bad results on front side of a PLA print only

    Well I've installed the Tinkered firmware and reduced the onboard acceleration down to 1500mm/s... We'll see if that makes any difference...

    I'll report back asap.


    Thanks.

     

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    Posted (edited) · Bad results on front side of a PLA print only

    Same exact results on same places with Tinker firmware and acceleration reduced to 1500 using the same gcode... 

    So what is it? 

     

    can't be stability as the rear part still comes out perfect!

     

    temp? too cold then? shall I try with the door CLOSED instead??

     

    20190401_094619.jpg

    20190401_094615.jpg

    Edited by bolsoncerrado
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    Posted · Bad results on front side of a PLA print only

    Which slicer do you use?

    Can you show pictures of the layer view (for the particular areas), or in case of Cura: can you share a project file?

    Is there a significant amount of travel moves on the "bad" side or something like that?

     

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    Posted (edited) · Bad results on front side of a PLA print only

    It's simplify3D. We've been using it for all projects since we started back in 2014 and we still have to find a reason to try any other slicer... I don't really think it's a slicer issue:

     

    https://imgur.com/PgTwnq9

     

    The amount of "moves" seem quite simetrical to me, compared to back and front faces.

     

    Edited by bolsoncerrado
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    Posted · Bad results on front side of a PLA print only
    6 minutes ago, bolsoncerrado said:

    The amount of "moves" seem quite simetrical to me, compared to back and front faces.

     

    ok, at least one more thing that can be ruled out... 🤷‍♂️

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    Posted · Bad results on front side of a PLA print only

    Increased PLA temp to 230 *AND* closed the enclosure door for the whole print (while reduced bed temp from 60 to 50) and while results are still not perfect, they're indeed way better.... wow...

     

    20190402_091149.thumb.jpg.3dd828456903b46fa1b6f47475196268.jpg

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    Posted · Bad results on front side of a PLA print only

    Does this effect also happen when you print a simple square tower, without any details, and without curves? In single-wall shels, and double wall shells? If yes, that would definitely rule-out model-geometry specific causes.

     

    I have no explanation for this effect, since normally PLA is supposed to print better when cool? At least in my experience... Or are there strong and variable air flows in the environment of your printer? Which would cause sudden temp changes of the nozzle?

     

    What if you put a desktop fan in front of the printer, to provide plenty of cooling air: does it get worse, or better?

     

    Or vibrations that only occur when the nozzle is printing in front?

     

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    Posted · Bad results on front side of a PLA print only

    I can't find any logic either. 

     

    The printer has been active alone, no airflow no aircurrents no people walking by, just low ambient temp of around 17-18C for a relatively high temp PLA, no vibrations from other devices except the printer itself... And by being at 50mm/s and 1500mms acceleration I think I should be getting better results but oh well.... 😞

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