<p>I managed to confirm the dragged layers were mostly due to <strong>under-extrusion</strong>.</p>

<p>I had a <code>faulty extruder</code> (clicking sound) and once I swapped it out it was greatly improved.</p>

<p>It's worth noting I also had a slight <code>z-wobble</code> issue so that could have played a role.</p>

<p>Hopefully this can help somebody out as I hadn't seen this kind of symptom in any of the print quality guides.</p>

CC BY-SA 4.0
2020-05-03T06:28:09.127Z
2020-05-03T06:28:09.127Z
Antoine Zambelli
<p>I'm trying to diagnose a print issue that <em>looks</em> like a missed layer (sorry, first-time printer here)</p>

<p><a href="https://i.sstatic.net/O4bIZ.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/O4bIZ.jpg" alt="side-view"></a>
and
<a href="https://i.sstatic.net/QOlZL.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/QOlZL.jpg" alt="top-view"></a></p>

<p>Specs:</p>

<ul>
<li>Printer: QIDI Tech X-Plus (direct drive).</li>
<li>Material: PLA.</li>
<li>Extruder temp: 200&nbsp;&deg;C.</li>
<li>Bed temp: 60&nbsp;&deg;C (70&nbsp;&deg;C first layer).</li>
<li>Print speed: 60&nbsp;mm/s (actually 48&nbsp;mm/s on non-infill because of <code>min_layer_time</code>).</li>
<li>Retraction distance: 2&nbsp;mm.</li>
</ul>

<p>Started from a new printer: I was getting imperfect prints (lesser version of this, functional part) and contacted QIDI support. They eventually replied that my bed was too low but I had since lowered the bed on a misdiagnosis. They supplied a slightly modified G-code but that also failed in a similar way.</p>

<p>Since then, I've been raising the bed bit by bit to try to fix this issue. I don't care about the little whiskers much, but the solid "connecting lines" are a problem.</p>

<p>Questions:</p>

<ol>
<li>Is this actually a bed-leveling/height issue?</li>
<li>What is this defect called (whatever the cause)? I've been googling but can't find something that looks like this.</li>
<li>Is there a better way of fixing bed height issues than just printing->tweaking bed height->printing?</li>
</ol>

<p>I'd appreciate any help diagnosing this issue - even if it's just the name of this problem. I have no experience disassembling/looking at hardware but I could always give it a shot.</p>

<h2>Update</h2>

<p>As per comments I took a look at <code>coasting</code> and ran some tests. I first re-leveled the bed manually (I'll call that height=0). I don't want to add tons of pictures so I'll show the baseline, and "bad" refers to similar failure as above.</p>

<pre><code>+--------+--------------+------------+-----------------------+-----------------+--------------+-------------+
|        | Combing      | Coasting   | Retraction distance   | Extruder temp   | Bed height   | Results     |
|--------+--------------+------------+-----------------------+-----------------+--------------+-------------|
| Test_1 | infill only. | off.       | 2.0 mm.               | 200 C.          | 0.           | Baseline.   |
| Test_2 | infill only. | off.       | 2.0 mm.               | 200 C.          | +0.05 mm.    | ~ Baseline. |
| Test_3 | off.         | off.       | 2.0 mm.               | 200 C.          | 0.           | Bad.        |
| Test_4 | infill only. | off.       | 1.5 mm.               | 200 C.          | 0.           | Bad.        |
| Test_5 | infill only. | off.       | 2.0 mm.               | 190 C.          | 0.           | TBD         |
+--------+--------------+------------+-----------------------+-----------------+--------------+-------------+
</code></pre>

<p>(+/- 0.05 mm height achieved with clicks of "fast leveling")</p>

<p>Test 1 external view:
<a href="https://i.sstatic.net/Mi53A.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/Mi53A.jpg" alt="test_1_out"></a></p>

<p>Test 1 internal view:
<a href="https://i.sstatic.net/amP77.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/amP77.jpg" alt="test_1_in"></a></p>

<h2>Update</h2>

<p>I think I've confirmed an <strong>under-extrusion</strong> problem. Here is a top layer printing I stopped partway through.</p>

<p><a href="https://i.sstatic.net/YCgJH.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/YCgJH.jpg" alt="test_5_top_layer"></a></p>

<p>This looks exactly like <a href="https://www.simplify3d.com/support/print-quality-troubleshooting/gaps-in-top-layers/" rel="nofollow noreferrer">Simplify3D's Guide</a>. So I manually pushed through, removed, and re-inserted the filament - and cleaned the nozzle with a brush.</p>

<p>I then ran a new print and noticed a clicking sound in the extruder (I don't know if it's new or if I simply noticed because I was focused on under-extrusion problems) - the print failed in the same "dragging" way as above, but the top layers were slightly better.</p>

<p>I'm now going through the list of possible causes of clicking extruder + under-extrusion.</p>

CC BY-SA 4.0
2020-04-23T21:41:20.577Z
It looks like the layer wasn't missed but failed to adhere and instead got dragged around until it stuck in the wrong place. This might be due to underextrusion at the start of the wall line, due to having lost (oozed) material elsewhere just before starting it. You say your retraction is 2 mm. Is your machine direct drive or bowden? If bowden that's way too low; minimum is around 5 or 6 mm. Also "combing" can cause this problem.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2020-04-23T21:48:24.920Z
@R..GitHubSTOPHELPINGICE it's direct drive (as per the printer specs). If combing is the same as `coasting` then it is enabled. Slicer `coasting: coasting replaces the last part of an extrusion path with a travel path. The oozed material is used to print the last piece of the extrusion path in order to reduce stringing.`. I think they're different?
Antoine Zambelli
CC BY-SA 4.0
2020-04-23T21:51:50.793Z
No, combing is not the same as coasting, and coasting is a **very harmful** option and probably the cause of this. It inherently causes underextrusion (total extruded material will be less than the nominal mass of the object). Turn it off. If you have stringing it means your retraction settings are wrong, not that you want to underextrude to compensate for it.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2020-04-23T21:54:05.067Z
I was *just* reading https://3dprinting.stackexchange.com/questions/5276/combing-and-coasting based on your first comment and was just about to give it a shot without coasting...which does seem very problem-prone. I'll update once I have a new print underway.
Antoine Zambelli
CC BY-SA 4.0
2020-04-24T02:00:05.077Z
I re-leveled the bed to run some tests. 1st test is combing + no coasting, it already looks *much* better. I'll try no combing + no coasting next and then play with bed height if needed...I'll update once I have a few tests done in case other newbies come across this.
Antoine Zambelli
CC BY-SA 4.0
2020-04-24T23:21:57.393Z
I managed to get one _much_ better print with: combing (infill only), no coasting, otherwise same specs. But since then it started having the same problem with every variation of parameters I try (no combing, retraction distance 1.5 mm, bed height + 0.05 mm) - any other ideas apart from coasting? I was thinking maybe turning off `retract after layer change`?
Antoine Zambelli
CC BY-SA 4.0
2020-04-25T01:01:31.820Z
I don't follow - with same settings, it went back to producing bad results? BTW you never answered if your printer is bowden or direct drive. That makes a difference to recommendations for this.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2020-04-25T01:16:03.387Z
@R..GitHubSTOPHELPINGICE I've updated the question with results, that'll make more sense! It's direct drive.
Antoine Zambelli
<print-quality><extrusion><layer-height><qidi-tech-x-plus>
Partially missed / dragged layers
Antoine Zambelli
# Partially missed / dragged layers

(Asked by: username_0 on 2020-04-23)

I'm trying to diagnose a print issue that looks like a missed layer (sorry, first-time printer here)

and

Specs:

Printer: QIDI Tech X-Plus (direct drive).
Material: PLA.
Extruder temp: 200 °C.
Bed temp: 60 °C (70 °C first layer).
Print speed: 60 mm/s (actually 48 mm/s on non-infill because of min_layer_time).
Retraction distance: 2 mm.

Started from a new printer: I was getting imperfect prints (lesser version of this, functional part) and contacted QIDI support. They eventually replied that my bed was too low but I had since lowered the bed on a misdiagnosis. They supplied a slightly modified G-code but that also failed in a similar way.
Since then, I've been raising the bed bit by bit to try to fix this issue. I don't care about the little whiskers much, but the solid "connecting lines" are a problem.
Questions:

Is this actually a bed-leveling/height issue?
What is this defect called (whatever the cause)? I've been googling but can't find something that looks like this.
Is there a better way of fixing bed height issues than just printing->tweaking bed height->printing?

I'd appreciate any help diagnosing this issue - even if it's just the name of this problem. I have no experience disassembling/looking at hardware but I could always give it a shot.
Update
As per comments I took a look at coasting and ran some tests. I first re-leveled the bed manually (I'll call that height=0). I don't want to add tons of pictures so I'll show the baseline, and "bad" refers to similar failure as above.
+--------+--------------+------------+-----------------------+-----------------+--------------+-------------+
|        | Combing      | Coasting   | Retraction distance   | Extruder temp   | Bed height   | Results     |
|--------+--------------+------------+-----------------------+-----------------+--------------+-------------|
| Test_1 | infill only. | off.       | 2.0 mm.               | 200 C.          | 0.           | Baseline.   |
| Test_2 | infill only. | off.       | 2.0 mm.               | 200 C.          | +0.05 mm.    | ~ Baseline. |
| Test_3 | off.         | off.       | 2.0 mm.               | 200 C.          | 0.           | Bad.        |
| Test_4 | infill only. | off.       | 1.5 mm.               | 200 C.          | 0.           | Bad.        |
| Test_5 | infill only. | off.       | 2.0 mm.               | 190 C.          | 0.           | TBD         |
+--------+--------------+------------+-----------------------+-----------------+--------------+-------------+

(+/- 0.05 mm height achieved with clicks of "fast leveling")
Test 1 external view:

Test 1 internal view:

Update
I think I've confirmed an under-extrusion problem. Here is a top layer printing I stopped partway through.

This looks exactly like Simplify3D's Guide. So I manually pushed through, removed, and re-inserted the filament - and cleaned the nozzle with a brush.
I then ran a new print and noticed a clicking sound in the extruder (I don't know if it's new or if I simply noticed because I was focused on under-extrusion problems) - the print failed in the same "dragging" way as above, but the top layers were slightly better.
I'm now going through the list of possible causes of clicking extruder + under-extrusion.

**Tags:** print-quality, extrusion, layer-height, qidi-tech-x-plus
> **Comments:**
> **username_1**: It looks like the layer wasn't missed but failed to adhere and instead got dragged around until it stuck in the wrong place. This might be due to underextrusion at the start of the wall line, due to having lost (oozed) material elsewhere just before starting it. You say your retraction is 2 mm. Is your machine direct drive or bowden? If bowden that's way too low; minimum is around 5 or 6 mm. Also "combing" can cause this problem.  
> **username_0**: @R..GitHubSTOPHELPINGICE it's direct drive (as per the printer specs). If combing is the same as `coasting` then it is enabled. Slicer `coasting: coasting replaces the last part of an extrusion path with a travel path. The oozed material is used to print the last piece of the extrusion path in order to reduce stringing.`. I think they're different?  
> **username_1**: No, combing is not the same as coasting, and coasting is a **very harmful** option and probably the cause of this. It inherently causes underextrusion (total extruded material will be less than the nominal mass of the object). Turn it off. If you have stringing it means your retraction settings are wrong, not that you want to underextrude to compensate for it.  
> **username_0**: I was *just* reading https://3dprinting.stackexchange.com/questions/5276/combing-and-coasting based on your first comment and was just about to give it a shot without coasting...which does seem very problem-prone. I'll update once I have a new print underway.  
> **username_0**: I re-leveled the bed to run some tests. 1st test is combing + no coasting, it already looks *much* better. I'll try no combing + no coasting next and then play with bed height if needed...I'll update once I have a few tests done in case other newbies come across this.  
> **username_0**: I managed to get one _much_ better print with: combing (infill only), no coasting, otherwise same specs. But since then it started having the same problem with every variation of parameters I try (no combing, retraction distance 1.5 mm, bed height + 0.05 mm) - any other ideas apart from coasting? I was thinking maybe turning off `retract after layer change`?  
> **username_1**: I don't follow - with same settings, it went back to producing bad results? BTW you never answered if your printer is bowden or direct drive. That makes a difference to recommendations for this.  
> **username_0**: @R..GitHubSTOPHELPINGICE I've updated the question with results, that'll make more sense! It's direct drive.  

---

## 1 answers

### Answer by username_0 on 2020-05-03. Score: 0 | Accepted answer

I managed to confirm the dragged layers were mostly due to **under-extrusion**.

I had a `faulty extruder` (clicking sound) and once I swapped it out it was greatly improved.

It's worth noting I also had a slight `z-wobble` issue so that could have played a role.

Hopefully this can help somebody out as I hadn't seen this kind of symptom in any of the print quality guides.


---

