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Cura 4.1 Quality is stringy and tree structure fails.

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Posted · Cura 4.1 Quality is stringy and tree structure fails.

I know not everyone wants to read the full story, so I'm breaking it down into two sections.

 

Short Version:

 

My Miniatures using Tree structures are are too weak at the connecting point and parts get knocked over by the extruder before they connect to the main part of the model. I do not want to add z hop to the printer as it effectively doubles the printing time.

 

Also, in this process, the parts are too stringy. I'm assuming I have to raise my temp, but I don't know for sure. Any help on either of these are appreciated.

 

Setup:

 

Software: Cura 4.1 attached to an OctoPrint Server on OctoPi

3D Printer: Iverntech D1 Kossel Delta with Heated and Self-Leveling bed. (Similar to Anycubic Kossel Delta with added features)

Filament: Inland Brand PLA+ 1.75mm (Print Temp 205C-225C)

Nozzle: 0.4mm (Will be switching to 0.25mm in the semi-near future)

 

Long Version:

 

I'm trying to print a few miniatures for a DND campaign that my cousin runs, and I can't seem to get the settings right in Cura. I've been playing around with the settings for the last 4 weeks now and I'm actually starting to get frustrated. Before the PLA+ I was running normal PLA and it printed "Okay" at best.

 

After playing around with the settings, I got the PLA+ quality to match closely to that of the normal PLA. However, now parts of the model on a tree structure (which I know is experimental) get knocked over by the extruder before connecting to the main model. I think the points are weak for easy cleanup, but its still knocking everything over. The theory that the support is too thin at connection is supported by another print where the model was increased to 125% scaling in cura and the structures were sound.

 

Also, When I'm printing the model gets blobs and stringy bits between "Floating" sections on that layer. what can I do to reduce both of these issues? Images and exported profile attached.

 

Any help or suggestions is greatly appreciated!!

 

IMG_0554.thumb.jpg.b9840aa97bcb73a78910ef184cdffa25.jpgIMG_0557.thumb.jpg.e39a8c15a527644c455af0d3655746c4.jpgIMG_0555.thumb.jpg.18dcb48080e7970643fbaa23d5523863.jpgPreview_Nameless_Hero.thumb.JPG.85253854eee883d54c987e39e1d7e8b4.JPGPrepare_nameless_hero.JPG.db5cdf18dd63da34a0d1ed738d2a650d.JPGModel_Profile.curaprofile

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Posted · Cura 4.1 Quality is stringy and tree structure fails.

Sorry I just skimmed and I'm only addressing stringing. 

1) Lower temp helps stringing more than increased.

2) Slowing down helps even more because there is less pressure in the nozzle

3) The most important is retraction.  Your models appear to be quite small so the default retraction settings are probably way off.  The key thing is: 

retraction minimum travel  (lower that maybe to 0?)

maximum retration count (raise that maybe to 100?)

 

Look at your part in layer view and turn on the checkbox to see "moves" in blue and note the dark blue versus light blue moves.  One is a retracting move (light blue) and the other is non-retracting.  You want to get rid of all the non-retracting moves between parts of your model.

 

Note however if you do too many retractions on the same exact spot of filament that you can grind it down to a point where you get a print failure (stops extruding).  This is less likely at lower speeds (means lower pressure in nozzle which means lower stress on filament at feeder).  But typically if the same spot of filament goes through the feeder back and forth more than 20 times it can cause a failure.  But if printing slow 100 times should be okay.

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Posted · Cura 4.1 Quality is stringy and tree structure fails.

Note also that smaller nozzles and longer nozzles leak less so string less.  A friend of mine has an e3dv6 0.4mm nozzle that leaks much more than my 3dsolex 0.4mm nozzle for this reason.  The "race" nozzles from 3dsolex have more internal geometry which means more surface area for the liquid filament to stick to which can reduce stringing (and ironically lower viscosity due to better heat transfer).

 

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Posted · Cura 4.1 Quality is stringy and tree structure fails.

One more thing - get a butane pen that makes a flame.  Put the flame over those strings for about 1/10 of a second.  It will make many of them disappear.  The remaining ones need to be removed mechanically.

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Posted · Cura 4.1 Quality is stringy and tree structure fails.

Thank you for the reply, I just got home and I'm about to try this for the stringing, thank you!

 

Also, the biggest issue for me is the parts that are falling off when knocked over by the extruder, do you or anyone else have any experience with this? Any hints or tips would be appreciated with that as well. At least to get going in the right direction.

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Posted · Cura 4.1 Quality is stringy and tree structure fails.

in Cura 4.1.0 I only have travels in dark blue and the light blue are support structures. How do I check for the different types of travel, and eliminate the non-retracting travels? 

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Posted · Cura 4.1 Quality is stringy and tree structure fails.

Alternatively; enable the ooze shield and print more models at the same time. The ooze shield will give it something to wipe the nozzle on and printing more models at once will allow for more time for the layers to cool.

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Posted · Cura 4.1 Quality is stringy and tree structure fails.

the antler-like constructs on the left photo were explained to me as "antennae" and result from there being a tiny bit of filament drooping from the nozzle as it approaches a wall. It deposits that drop on the perimeter of the wall forming the root of an antenna. Then the next layer the drop hits the prior drop, and so on, forming those upward-growing antlers.

 

So probably using a bit more retraction might help.

 

 

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