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Stringing on a new level but why?


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Posted · Stringing on a new level but why?

Alright, I don’t know what I should do right now and where to start! I did a stringing test on teaching tech and went perfect with the last two but when I am doing another stringing test with the settings in Cura i get a new spider nest!
What should I look for? Change? Something I have missed?
Here are all the settings >> https://youtu.be/MXZjUOUzSJY
Here are the retraction settings from Teaching Tech
https://imgur.com/a/vHjB06x

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    Posted · Stringing on a new level but why?

    What printer are you using?  You didn't mention, but are you printing PETG?

    Within those settings - the retraction distance does not change but for each level - 2 variables change.  For instance, from A to B the retraction speed increases from 25 to 30 and the z-hop goes from 0 to .2.

     

    Are you doing other tests where the retraction distance changes?  The 4.0 retraction distance would seem to indicate you have a bowden printer.  The default retraction distance (for example) of an Ender 3 is 6.5mm.  The retraction distance of bowden machines is effected by the amount of "slop" in the bowden system.  The tube slides in and out of each coupler, it flexes, the length of filament within the tube during a retract is different than the length during a prime.  A retraction distance of 4 with a normal amount of slop and you may be down to 2mm (or less) of actual retraction at the nozzle.

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    Posted · Stringing on a new level but why?
    16 minutes ago, GregValiant said:

    What printer are you using?  You didn't mention, but are you printing PETG?

    Within those settings - the retraction distance does not change but for each level - 2 variables change.  For instance, from A to B the retraction speed increases from 25 to 30 and the z-hop goes from 0 to .2.

     

    Are you doing other tests where the retraction distance changes?  The 4.0 retraction distance would seem to indicate you have a bowden printer.  The default retraction distance (for example) of an Ender 3 is 6.5mm.  The retraction distance of bowden machines is effected by the amount of "slop" in the bowden system.  The tube slides in and out of each coupler, it flexes, the length of filament within the tube during a retract is different than the length during a prime.  A retraction distance of 4 with a normal amount of slop and you may be down to 2mm (or less) of actual retraction at the nozzle.

    Hi!
    Thank you for your fast reply to my issues! 
    The printer that I am using is a Prusa Mini+, over 4mm will in retraction cause big extrusion issues as clogs and jams! The Prusa team told me never to go over 4.2mm, that will create issues such as jams and clogs!


    I am also printing PETG, its has been dried for 5h in an oven at recommended temperature from the filament maker.

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    Posted · Stringing on a new level but why?

    By all means stick with the manufacturers advice.

    PETG is stringy and I haven't found a way to eliminate all stringing.  I avoid Z-hop and print at 245 so the filament is more fluid.  That allows it to be retracted faster.  At 220 I would think you need to have a slower retract speed since the thicker plastic won't retract as fast.  Priming doesn't really effect stringing.  I print PETG at 35mm/sec with the outer walls at 30.  On real prints the type of Combing you choose will also have an effect.  With no z-hop and the nozzle traveling along pervious plastic, the stringing might be there but it's hard to notice until the nozzle crosses over air.  Dry PETG is good.  It gets even soupier than PLA when it has a high moisture content.

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    Posted · Stringing on a new level but why?
    8 hours ago, GregValiant said:

    By all means stick with the manufacturers advice.

    PETG is stringy and I haven't found a way to eliminate all stringing.  I avoid Z-hop and print at 245 so the filament is more fluid.  That allows it to be retracted faster.  At 220 I would think you need to have a slower retract speed since the thicker plastic won't retract as fast.  Priming doesn't really effect stringing.  I print PETG at 35mm/sec with the outer walls at 30.  On real prints the type of Combing you choose will also have an effect.  With no z-hop and the nozzle traveling along pervious plastic, the stringing might be there but it's hard to notice until the nozzle crosses over air.  Dry PETG is good.  It gets even soupier than PLA when it has a high moisture content.


    Got it finally working after 6h of testing but got another problem, it’s a tiny hole at the start of the print! It is missing an tiny area when it starts printing for some reason and I can’t understand why! 
    You can see the gap in left corner! 

    look at this! 
    Filter out tiny gaps is on/off 

    combing all, not in skin 

     

     

    DB4F7789-271C-483E-BD25-25E5E7A11134.jpeg

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    Posted · Stringing on a new level but why?

    It looks like it’s not extruding there or that it’s just ignores it, can’t find it in the preview in the slicer! 

    578FD90D-7BA0-4C58-82B2-FF8D5D911CBC.png

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    Posted · Stringing on a new level but why?

    Wow.  You are having a heck of a time.  I have no idea why that would happen.  Usually something like that is the model, but it's just a calibration cube right?  Maybe there was a long combing move before it and that is the start of an extrusion?  Too much oozing during a combing move will cause a delay at the start of the first extrusion after the move.  You are confident it's not in the preview?  (right now I have more questions than answers).  I think we can safely rule out a knot hole.  That's as far as I'm willing to go right now.

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    Posted · Stringing on a new level but why?
    33 minutes ago, GregValiant said:

    Wow.  You are having a heck of a time.  I have no idea why that would happen.  Usually something like that is the model, but it's just a calibration cube right?  Maybe there was a long combing move before it and that is the start of an extrusion?  Too much oozing during a combing move will cause a delay at the start of the first extrusion after the move.  You are confident it's not in the preview?  (right now I have more questions than answers).  I think we can safely rule out a knot hole.  That's as far as I'm willing to go right now.


    Have had the same issue on 3 models now and don’t know really why! I am confident that it’s not in the preview but will make a recording of the preview tomorrow and all my settings again. 
     

    I will also try and record the start of the print so can see more clearly but it’s just after the skirt when it’s moving the nozzle in to start printing. Then this issue appears directly to the first layer/s and even with after infill it’s still there! 
     

     

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    Posted · Stringing on a new level but why?

    Post the gcode file that shows the hole.  With the model loaded in Cura use "File | Save Project" and post the 3mf file here as well.

    There are certain combinations of settings (coasting, combing, retract at layer change, retract before outer wall) that sometimes don't play well together.  Maybe something will stick out.

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    Posted (edited) · Stringing on a new level but why?
    6 hours ago, GregValiant said:

    Post the gcode file that shows the hole.  With the model loaded in Cura use "File | Save Project" and post the 3mf file here as well.

    There are certain combinations of settings (coasting, combing, retract at layer change, retract before outer wall) that sometimes don't play well together.  Maybe something will stick out.

    Oh, that is understandable when you say it!

    I will very happily post the settings file when I get home, later today 


    Thanks!

    Edited by BamseMaster
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    Posted · Stringing on a new level but why?
    15 hours ago, GregValiant said:

    Post the gcode file that shows the hole.  With the model loaded in Cura use "File | Save Project" and post the 3mf file here as well.

    There are certain combinations of settings (coasting, combing, retract at layer change, retract before outer wall) that sometimes don't play well together.  Maybe something will stick out.

    Hi!
    Here is all the files! Hope you can find where it goes bad!
     

    OPM_visual-method-cube.3mf OPM_visual-method-cube.gcode

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    Posted (edited) · Stringing on a new level but why?

    Coasting is usually nice for skins.  On walls and with combing turned on, there is the coast distance (during which the pressure in the heat chamber is allowed to fall off) then a retraction followed by the travel motion.  All of that means that the prime is not sufficient to get extrusion started right away and I believe that is what we're seeing.

     

    This shot is from the Gcode file opened in Cura.  That whole corner shows the coasting all the way to the top of the model.

    BUT within the 3mf file Coasting is not enabled.  (You were trying to trick us weren't you.)

     

    These are the relevant lines from the gcode file:

    G1 X99.8 Y98.959 E16.35658
    G0 F1080 X99.8 Y99.801

    The nozzle extrudes to X99.8 Y98.959 and then coasts to X99.8 Y99.801 which is about 1mm.

     

    There is a reason that Coasting is in the Experimental section.  Sometimes it has too much of an effect on the resumption of extrusion.  Large prints that have a lot of combing moves can have the same problem as the oozing while traveling can make for insufficient prime on resumption.

     

    Untitled.thumb.png.eb31473e7e8381f47dcccb21d8e20be3.png

    Edited by GregValiant
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    Posted · Stringing on a new level but why?
    5 minutes ago, GregValiant said:

    You were trying to trick us weren't you.

    😁

     

    Thanks for explaining the white space. I had wondered about that.

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    Posted · Stringing on a new level but why?

    Actually, I made it all up.  I have no idea if any of that is true or not.🤪

     

    Cura shows the extrusion moves and with coasting enabled there is no extrusion there.  The nozzle travels there so that little part is a continuation (vector wise) but there is no E in the line of gcode so the pressure just bleeds off across that distance.

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    Posted · Stringing on a new level but why?
    4 minutes ago, GregValiant said:

    Actually, I made it all up.  I have no idea if any of that is true or not.🤪

    😂

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    Posted (edited) · Stringing on a new level but why?
    2 hours ago, GregValiant said:

    Coasting is usually nice for skins.  On walls and with combing turned on, there is the coast distance (during which the pressure in the heat chamber is allowed to fall off) then a retraction followed by the travel motion.  All of that means that the prime is not sufficient to get extrusion started right away and I believe that is what we're seeing.

     

    This shot is from the Gcode file opened in Cura.  That whole corner shows the coasting all the way to the top of the model.

    BUT within the 3mf file Coasting is not enabled.  (You were trying to trick us weren't you.)

     

    These are the relevant lines from the gcode file:

    G1 X99.8 Y98.959 E16.35658
    G0 F1080 X99.8 Y99.801

    The nozzle extrudes to X99.8 Y98.959 and then coasts to X99.8 Y99.801 which is about 1mm.

     

    There is a reason that Coasting is in the Experimental section.  Sometimes it has too much of an effect on the resumption of extrusion.  Large prints that have a lot of combing moves can have the same problem as the oozing while traveling can make for insufficient prime on resumption.

     

    Untitled.thumb.png.eb31473e7e8381f47dcccb21d8e20be3.png

    Oh, so that’s what happened here then! Did not know I did not have coasting on there! Sorry! But that’s explains a lot with those small tiny holes at all my prints from yesterday and back! Must had accidentally turned of coasting…

     

    but did a slice with coasting and without it and it’s seems todo the trick in the slicer now for the fun part! 3D printing! Hope it will work out really good! 😀

     

    thanks for taking your time and helping me out! Appreciate it very much! 

    Edited by BamseMaster
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    Posted (edited) · Stringing on a new level but why?
    On 7/13/2021 at 12:34 AM, BamseMaster said:

    Oh, so that’s what happened here then! Did not know I did not have coasting on there! Sorry! But that’s explains a lot with those small tiny holes at all my prints from yesterday and back! Must had accidentally turned of coasting…

     

    but did a slice with coasting and without it and it’s seems todo the trick in the slicer now for the fun part! 3D printing! Hope it will work out really good! 😀

     

    thanks for taking your time and helping me out! Appreciate it very much! 

    Worked out really good! Thanks!

    retraction (1).gcode

    Edited by BamseMaster
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