<p>I am trying to print Benchy at 50% scale out of nylon (trimmer line). And all is ok, but there is under-extrusion when the boards are already printed, but before printing the roof. Sometimes it is so severe that the roof comes off under slight pressure.</p>
<p>I tried temperatures of 250, 255 and 263 degrees, 0.45 * 0.2 and 0.6 * 0.3 extrusion size, no fan and slight cooling, and have seen no difference except sometimes under-extrusion occurs at the window level, but sometimes slightly higher (but not at the roof).</p>
<p>I left nylon overnight in oven at 60 - 65 degrees, but it had not dried completely, as the hairs tell. The speed was 30 - 40 mm/s, the slicer is Prusa slicer, the printer is Kingroon KP3S.</p>
<p>Full sized Benchy prints perfectly, except it bends due to thermal shrinking. I printed it at 250 degrees, 0.6 * 0.3 extrusion and 80 speed, so the extruder is totally fine.</p>
<p>The small layer size itself is also not the cause, as the smoke stack prints ok (at least when cooled). It could be extrusion of the nylon during head movement due to water boiling and therefore insufficient amount of plastic where it should be, but I can not see any significant lumps of plastic anywhere else.</p>
<p>What it can be and how can I overcome this?</p>
<p><a href="https://i.sstatic.net/aBSkF.jpg" rel="nofollow noreferrer" title="255 degrees 0.6*0.3 40mm/s"><img src="https://i.sstatic.net/aBSkF.jpg" alt="255 degrees 0.6*0.3 40mm/s" title="255 degrees 0.6*0.3 40mm/s" /></a></p>
<p><a href="https://i.sstatic.net/Gw7UW.jpg" rel="nofollow noreferrer" title="The same benchy broken"><img src="https://i.sstatic.net/Gw7UW.jpg" alt="The same benchy broken" title="The same benchy broken" /></a></p>
<p><a href="https://i.sstatic.net/3kUqm.jpg" rel="nofollow noreferrer" title="Left: 263 degrees 0.6*0.3 30mm/s, right: 255 degrees 0.45*0.2 40mm/s"><img src="https://i.sstatic.net/3kUqm.jpg" alt="Left: 263 degrees 0.60.3 30mm/s, right: 255 degrees 0.450.2 40mm/s" title="Left: 263 degrees 0.6*0.3 30mm/s, right: 255 degrees 0.45*0.2 40mm/s" /></a></p>
<p><a href="https://i.sstatic.net/d4SUR.jpg" rel="nofollow noreferrer" title="100% 250 degrees 0.6*0.3 80mm/s"><img src="https://i.sstatic.net/d4SUR.jpg" alt="100% 250 degrees 0.6*0.3 80mm/s" title="100% 250 degrees 0.6*0.3 80mm/s" /></a></p>

CC BY-SA 4.0
2023-05-07T18:16:32.507Z
They are very good photos, but they *seem* to show different prints of Benchy. It might be a good idea if you could [edit] your question and where it says `enter image description here`, please add a brief description for the photos to illustrate what they show and/or why they are different.
Greenonline
CC BY-SA 4.0
2023-05-07T18:42:02.407Z
@Greenonline i added the descriptions as you said but they are not shown in the post.
Обедающий философ
CC BY-SA 4.0
2023-05-07T18:52:50.180Z
Yes, it is a bit of a bug. You have to add image hover tags (move the mouse over the image and the text will show). I have edited those in for you now. Please check that they are correct. Thanks :-)
Greenonline
<underextrusion><prusaslicer><nylon>
Underextrusion on small layers
Обедающий философ
# Underextrusion on small layers

(Asked by: username_0 on 2023-05-07)

I am trying to print Benchy at 50% scale out of nylon (trimmer line). And all is ok, but there is under-extrusion when the boards are already printed, but before printing the roof. Sometimes it is so severe that the roof comes off under slight pressure.

I tried temperatures of 250, 255 and 263 degrees, 0.45 \* 0.2 and 0.6 \* 0.3 extrusion size, no fan and slight cooling, and have seen no difference except sometimes under-extrusion occurs at the window level, but sometimes slightly higher (but not at the roof).

I left nylon overnight in oven at 60 - 65 degrees, but it had not dried completely, as the hairs tell. The speed was 30 - 40 mm/s, the slicer is Prusa slicer, the printer is Kingroon KP3S.

Full sized Benchy prints perfectly, except it bends due to thermal shrinking. I printed it at 250 degrees, 0.6 \* 0.3 extrusion and 80 speed, so the extruder is totally fine.

The small layer size itself is also not the cause, as the smoke stack prints ok (at least when cooled). It could be extrusion of the nylon during head movement due to water boiling and therefore insufficient amount of plastic where it should be, but I can not see any significant lumps of plastic anywhere else.

What it can be and how can I overcome this?

[![255 degrees 0.6*0.3 40mm/s](https://i.sstatic.net/aBSkF.jpg "255 degrees 0.6*0.3 40mm/s")](https://i.sstatic.net/aBSkF.jpg "255 degrees 0.6*0.3 40mm/s")

[![The same benchy broken](https://i.sstatic.net/Gw7UW.jpg "The same benchy broken")](https://i.sstatic.net/Gw7UW.jpg "The same benchy broken")

[![Left: 263 degrees 0.60.3 30mm/s, right: 255 degrees 0.450.2 40mm/s](https://i.sstatic.net/3kUqm.jpg "Left: 263 degrees 0.6*0.3 30mm/s, right: 255 degrees 0.45*0.2 40mm/s")](https://i.sstatic.net/3kUqm.jpg "Left: 263 degrees 0.6*0.3 30mm/s, right: 255 degrees 0.45*0.2 40mm/s")

[![100% 250 degrees 0.6*0.3 80mm/s](https://i.sstatic.net/d4SUR.jpg "100% 250 degrees 0.6*0.3 80mm/s")](https://i.sstatic.net/d4SUR.jpg "100% 250 degrees 0.6*0.3 80mm/s")

**Tags:** underextrusion, prusaslicer, nylon
> **Comments:**
> **username_1**: They are very good photos, but they *seem* to show different prints of Benchy. It might be a good idea if you could [edit] your question and where it says `enter image description here`, please add a brief description for the photos to illustrate what they show and/or why they are different.  
> **username_0**: @Greenonline i added the descriptions as you said but they are not shown in the post.  
> **username_1**: Yes, it is a bit of a bug. You have to add image hover tags (move the mouse over the image and the text will show). I have edited those in for you now. Please check that they are correct. Thanks :-)  

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## 0 answers

