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Stringing starts at certain layer height


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Posted · Stringing starts at certain layer height

So I’m about to give up haha.

 

i got a used kobra 2 a month ago, and it worked like a charm! I decided I should replace the nozzle because it was getting a little worn and ever since it’s been stringing on every print. I must have done dozens of retraction tests and changing nearly every setting I can think of.

 

i printed the first one in the back, it came back perfect at 1mm so I used that to print the 4 corners test on the right which was perfect until the very top. I figured maybe it was the small tips making it mess up. So for fun I did one final test and I realized it seems like it fails at a certain layer height.

 

is this a cooling issue? 

IMG_5731.jpeg

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    Posted · Stringing starts at certain layer height

    Those strings are the kind that are super easy to clean up.  Personally I wouldn't care.  There are nasty strings and then there are this kind.  Having said that, I rarely get even this kind lately.

     

    Is this PETG?  PETG gets wet slowly over a month or 3 and strings more as it ages.  PLA does not need to be dried (DON'T DRY PLA - you are wasting your time).  That would explain your issue as it takes a month or 3 months or so and could coincide roughly with your new nozzle.

     

    Printing fast also increases this kind of stringing.  Printing with a high nozzle temp.  Printing without retraction.  Those are 3 things that can cause this.

     

    Also I'd look at the shoulder of the nozzle - the washer shaped ring around the nozzle hole.  Do you have a larger or smaller shoulder on the 2 different nozzles?

     

    I've pretty much never thrown away a nozzle.  I've been printing with a handful of printers for over 10 years now.  There are nozzles I prefer so there are nozzles that don't get used much.  But as far as I know they don't go bad.  They do accumulate gunk on the inside of the final passage.  A few cold pulls can fix that usually or I'll scrape the inside while at temp using a hypodermic needle.

     

     

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    Posted · Stringing starts at certain layer height
    25 minutes ago, gr5 said:

    They do accumulate gunk on the inside of the final passage.  A few cold pulls can fix that usually or I'll scrape the inside while at temp using a hypodermic needle.

    I think you have a lot more confidence about knowing what's actually inside your printer than I do. I've used a nozzle cleaner for mild buildup but I'm afraid I might hurt something if I shove it too far up there, especially now that I have a direct drive extruder.

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    Posted (edited) · Stringing starts at certain layer height
    7 minutes ago, Slashee_the_Cow said:

    I'm afraid I might hurt something if I shove it too far up there, especially now that I have a direct drive extruder.

    Creality sprite? Easy to disassemble and put back together. Not much you can hurt. There is a section of plsatic tube that has no part number I can find but seems to like to hord stupid bits of gunk. 

     

    Ask me how I know. 

    Edited by jaysenodell
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    Posted · Stringing starts at certain layer height
    5 hours ago, Slashee_the_Cow said:

    Have you tried putting another nozzle on it? If it started exactly when you changed the nozzle, the odds it's a dud nozzle are pretty high.

    Yes I ordered a dozen new nozzles and I tried 2 other ones. I might just order a new batch just incase. 

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    Posted · Stringing starts at certain layer height
    1 hour ago, gr5 said:

    Those strings are the kind that are super easy to clean up.  Personally I wouldn't care.  There are nasty strings and then there are this kind.  Having said that, I rarely get even this kind lately.

     

    Is this PETG?  PETG gets wet slowly over a month or 3 and strings more as it ages.  PLA does not need to be dried (DON'T DRY PLA - you are wasting your time).  That would explain your issue as it takes a month or 3 months or so and could coincide roughly with your new nozzle.

     

    Printing fast also increases this kind of stringing.  Printing with a high nozzle temp.  Printing without retraction.  Those are 3 things that can cause this.

     

    Also I'd look at the shoulder of the nozzle - the washer shaped ring around the nozzle hole.  Do you have a larger or smaller shoulder on the 2 different nozzles?

     

    I've pretty much never thrown away a nozzle.  I've been printing with a handful of printers for over 10 years now.  There are nozzles I prefer so there are nozzles that don't get used much.  But as far as I know they don't go bad.  They do accumulate gunk on the inside of the final passage.  A few cold pulls can fix that usually or I'll scrape the inside while at temp using a hypodermic needle.

     

     

    It’s PLA, the old nozzle I had initially looked like the hole was slightly larger and a little misshapen. I checked and it was .4 as well. 
     

    I’ve messed around and ran different tests with retraction speed, retraction distance, travel speed, coasting. My next attempt later today is to test the esteps but idk why that would change over a nozzle change 

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    Posted · Stringing starts at certain layer height
    1 hour ago, jaysenodell said:

    Creality sprite? Easy to disassemble and put back together. Not much you can hurt. There is a section of plsatic tube that has no part number I can find but seems to like to hord stupid bits of gunk. 

     

    Ask me how I know. 

    It’s a anycubic kobra 2. I’m just about at the point of disassembling the whole thing lol 

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    Posted · Stringing starts at certain layer height
    Just now, Stevens518 said:

    It’s a anycubic kobra 2. I’m just about at the point of disassembling the whole thing lol 

    Don't worry, he was talking to me. Just remember if you do disassemble it to either take a photo at every step, or better yet set something up to record a video of the entire process. That way when you're wondering how the fork you put it back together you've got the reference material.

     

    1 hour ago, jaysenodell said:

    Creality sprite? Easy to disassemble and put back together. Not much you can hurt. There is a section of plsatic tube that has no part number I can find but seems to like to hord stupid bits of gunk. 

    Don't think the E3V3SE has a regular one of those. The extruder and hot end are both under the same plastic shroud which is only a little bigger than the one that was on the hot end of my E3V2Neo, let alone if I'd bolted a Sprite to the top of it.

     

    1 hour ago, jaysenodell said:

    Ask me how I know. 

    I'm going to presume you wanted to order about a dozen replacements so you'd be good for a month or so but weren't capable of telling anyone what you wanted with a better description than "little bit of tube" so they had no idea what you wanted, but how do you know?

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    Posted · Stringing starts at certain layer height

    After you slice your calibration part, look at it in preview mode in "line type" mode.  All non-extruding movements (aka travel moves) are either light blue or dark blue.  Locate some of each.  Dark blue moves are non-retracting moves.  Light blue are retracting moves.

     

    Typically when the head moves from one "island" to another you get a retraction to avoid stringing.  Look at your part in preview mode and make sure the travel moves through "air" are all light blue.  If not then that could explain your stringing.  You can change your retraction settings to fix this - there are dozens of settings that affect retraction.

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    Posted · Stringing starts at certain layer height
    2 hours ago, Slashee_the_Cow said:

    Don't think the E3V3SE has a regular one of those. The extruder and hot end are both under the same plastic shroud which is only a little bigger than the one that was on the hot end of my E3V2Neo, let alone if I'd bolted a Sprite to the top of it.

    redit says it's the standard sprite. But redit is only correct a small fraction of the time redit thinks redit is correct. If it is the sprite, you can do the service on it pretty simple. I need to do it just to ruin my weekend of printing. 

     

    2 hours ago, Slashee_the_Cow said:
    3 hours ago, jaysenodell said:

    Ask me how I know. 

    I'm going to presume you wanted to order about a dozen replacements so you'd be good for a month or so but weren't capable of telling anyone what you wanted with a better description than "little bit of tube" so they had no idea what you wanted, but how do you know?

    Close but more me being unable to get any filament to load and nothing "up the snout" to clean it out. Had to pull it all appart and found the tube with all kinds of pla and petg globbed around it. top and bottom. Started looking for it online. nothing. picked it up and wipped it with a towel and all the globs fel off. Safe for now! I assume its just the same stuff the bowdens are made out of. I'm ignoring it for now. 

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