Strange extrusion between threaded parts
 
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enzo
 enzo
(@enzo)
Active Member
Strange extrusion between threaded parts

Hi,

please can anyone help me to understand why I get these extrusions in the middle of threads (attached photos)?

The .STL and g-code files are enclosed, too. They were made by Prusaslicer Version 2.4.0-alpha3+win64.

The g-code visualization of the layers execution doesn't show this strings: where are they added? The files are transferred to my Modix Big60 (fw Marlin 1.19) via Pronterface.

I enclose a comparable part without any thread that is printed correctly without strings in the middle. Because of this I guess the problem is in the generation of .STL from the thread libraries but I printed similar parts in the past with the same libraries and they were perfect.

Maybe some setting in the new version has to be tweaked?

Thanks for any help!

Best Answer by Neophyl:

That not technically stringing in the normal definition.  Thats your perimeters not sticking to the layers below and being dragged across to other points on the circle.  Stringing is fine left over filament as it does a travel usually.  

On your project when sliced, look at the preview.  All the dark blue areas are overhang and that is what is not adhering to the layers below as theres nothing below to stick to.  This is primarily due to your 0.3mm layer height.  For threads of this size you need to go lower, 0.15 should be sufficient but 0.1 would give a cleaner thread.

btw if your filament is really pla nx3 from extrudr then a higher temperature than 205 would be better.  That will improve layer adhesion which will help with newly laid down filament sticking to the previous layers.

Some other questions about your settings, mainly curiosity but why the 20 layer high 3 perimeter width skirt ?  Its not going to do anything and the brim will act to prime things just as well as the skirt.  

You must have really bad bed adhesion if your first layer needs to be 0.4mm thick and with over 0.8mm extrusion width.  What printer/bed surface are you using ?  That part on a mk3 wouldn't need any brim and a more 'normal' height of 0.2 with the standard extrusion width too.
Haven't seen such settings since the old glass bed days 🙂

Posted : 16/10/2021 3:15 pm
sylviatrilling
(@sylviatrilling)
Estimable Member
Pix and .3mf

You attached 2 stl's and 2 gcodes but no pictures came through. Also, a .3mf file would be more useful for figuring out what is going on. 

Posted : 16/10/2021 3:33 pm
enzo
 enzo
(@enzo)
Active Member
Topic starter answered:
Images and .3mf file

2 images were in the .rar. I enclose again them here with the .3mf file.

Thanks.

Posted : 16/10/2021 3:43 pm
Neophyl
(@neophyl)
Famed Member

That not technically stringing in the normal definition.  Thats your perimeters not sticking to the layers below and being dragged across to other points on the circle.  Stringing is fine left over filament as it does a travel usually.  

On your project when sliced, look at the preview.  All the dark blue areas are overhang and that is what is not adhering to the layers below as theres nothing below to stick to.  This is primarily due to your 0.3mm layer height.  For threads of this size you need to go lower, 0.15 should be sufficient but 0.1 would give a cleaner thread.

btw if your filament is really pla nx3 from extrudr then a higher temperature than 205 would be better.  That will improve layer adhesion which will help with newly laid down filament sticking to the previous layers.

Some other questions about your settings, mainly curiosity but why the 20 layer high 3 perimeter width skirt ?  Its not going to do anything and the brim will act to prime things just as well as the skirt.  

You must have really bad bed adhesion if your first layer needs to be 0.4mm thick and with over 0.8mm extrusion width.  What printer/bed surface are you using ?  That part on a mk3 wouldn't need any brim and a more 'normal' height of 0.2 with the standard extrusion width too.
Haven't seen such settings since the old glass bed days 🙂

Posted : 16/10/2021 4:13 pm
enzo
 enzo
(@enzo)
Active Member
Topic starter answered:
Strange extrusion between threaded parts answers

Hi Neophyl,

thanks for your answer. I'll try with this layer and temperature settings and let you know if this goes fine.

About your curiosity: I'm going on with many trials with different filaments so sometimes I forget to tweak some "not crucial" parameters as the skirt (needed for a previous print) and so for the .4 + over extrusion first layer which I tried on with a different filament.

I've a PEI covered bed in a Modix Big60 and usually prints adhere vey well, sometimes too much 🙂

Posted : 16/10/2021 5:33 pm
enzo
 enzo
(@enzo)
Active Member
Topic starter answered:
Print is perfect now!

Thanks a lot Neophyl, no "stringing" now and the thread is perfect!

Posted : 17/10/2021 5:24 pm
Neophyl
(@neophyl)
Famed Member

Glad you got it printing.  That is one big assed printer 🙂  I checked it out afterwards and I wish I could afford the Big40 from their range, although even the 650 shipping makes me wince lol.

Posted : 17/10/2021 9:06 pm
enzo
 enzo
(@enzo)
Active Member
Topic starter answered:
It's great but...

The biggest fun is building it! If you're into making I recommend it: a litlle effort but great satisfaction!

Posted : 17/10/2021 9:24 pm
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