<p>I had problems with jamming PETG due to retraction.  My model had many retraction moves, such that the amount of filament used during a printing move was less than the retraction distance.  I found that several trips through the feed gear flattened the filament, which caused two problems.  </p>

<ol>
<li>The flattened (or ovaled) filament had trouble fitting through the round holes and tubes, and</li>
<li>Since it was thinner, the filament was not gripped as tightly so there was less force pushing it.</li>
</ol>

<p>I reduced my feed gear pressure and the problem stopped.</p>

<p>PETG is not as stiff as PLA.  The multiple trips through mangle flattened it.</p>

CC BY-SA 4.0
2019-07-13T21:33:31.050Z
2019-07-13T21:33:31.050Z
cmm
<p>Recently I had this problem where I needed to change filament from PLA to PET-G or similar. And... filament jam. After playing around with different settings and speeds and still getting the same results I had to clean everything. And again during a print, it jammed.</p>

<p>I brought a new nozzle, heating cartage, Teflon (PTFE) tube and some additional components(fans, new wires and so on) but still was the same. Now I'm waiting for a new set of hotend Mk8<sup>Design Needed</sup> kit. </p>

<p>A week after the order and still waiting, I played with retraction a little. By default, it was set to 0.8&nbsp;mm on Sli3er but I had set it to 4-6&nbsp;mm because it gives the best results and no stringing. I changed it again to 1.5-2&nbsp;mm and... no more jamming at the cost of getting stringing. I'm using PLA which I never had experienced strings before.</p>

<p>So, in summary, the problem occurs due my retraction setting. Either I have to live with strings and no jam problems or no strings but jamming problems during printing.</p>

<p>Have someone had same problem as me? How did you fixed it? </p>

<ul>
<li>Printer AlfaWise U30(bowden type) but it's no longer the same. </li>
<li>Motherboard: MKS 1.4 Gen A4988 + DRV8825 Stepper drivers(no problems here)</li>
<li>PID(Autotune), Calibrations and so on done correctly.</li>
<li>Firmware latest marlin 1.1.9 (Tried bugfix but the same)</li>
<li>Sofware for slicing PE Sli3er (Tried Ultimaker Cura with same model and same problem)</li>
</ul>

CC BY-SA 4.0
2019-07-13T17:49:12.447Z
Would you please provide some additional things to make it easier? You said Mk8, do you mean a Makerbot Mk8 Hotend? Or did you update to an all-metal hotend? What is your standard printing temperature? What is your retraction speed?
Trish
CC BY-SA 4.0
2019-07-13T17:49:23.150Z
There are more settings to fight stringing, e.g. lower print temperature. PETG is more prone to stringing opposed to other types of plastic.
0scar
CC BY-SA 4.0
2019-07-13T20:12:37.193Z
I wrote what I changed. I haven't touched the hotend. It is original what Alfawise had. They used makerbot mk8 hotend (I believe so) but not quite sure about. Because of that I ordered a new one and different. Alfawise doesn't like to share information about they products. The firmware wasn't open source like marlin. Sorry about the temperature or printing. For PLA is 200-220(recommended) So between those temp. It's still the same. Retract is default in sli3er (35mm/s) I tried from 25 to 50 and nothing... same
fluSneez
CC BY-SA 4.0
2019-07-13T20:21:13.503Z
The most accurate link to hotend:
https://www.amazon.com/Longer-Printer-Extruder-Creality-Alfawise/dp/B07PB2P5N1
fluSneez
CC BY-SA 4.0
2019-07-14T04:11:34.017Z
Not an answe, but assuming PTFE is a bowden setup, you definitely need at least 4-6 mm of retraction to avoid stringing. 0.8-2mm is not going to cut it anywhere but a direct drive extruder, and I'd be doubtful that it's even really sufficient there. So you should try to fix this right.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2020-09-24T16:04:54.220Z
I had same issue when switching to PETG.
Perry Webb
CC BY-SA 4.0
2020-09-24T16:23:46.947Z
With a Reprap x400 I could retract 6 mm, but this did not completely get rid of the stringing.  Retracting to 20 mm jammed the extruder at the first retract.
Perry Webb
<pla><diy-3d-printer><extrusion><petg>
Retraction Jamming Problem!
fluSneez
# Retraction Jamming Problem!

(Asked by: username_0 on 2019-07-13)

Recently I had this problem where I needed to change filament from PLA to PET-G or similar. And... filament jam. After playing around with different settings and speeds and still getting the same results I had to clean everything. And again during a print, it jammed.

I brought a new nozzle, heating cartage, Teflon (PTFE) tube and some additional components(fans, new wires and so on) but still was the same. Now I'm waiting for a new set of hotend Mk8Design Needed kit.

A week after the order and still waiting, I played with retraction a little. By default, it was set to 0.8 mm on Sli3er but I had set it to 4-6 mm because it gives the best results and no stringing. I changed it again to 1.5-2 mm and... no more jamming at the cost of getting stringing. I'm using PLA which I never had experienced strings before.

So, in summary, the problem occurs due my retraction setting. Either I have to live with strings and no jam problems or no strings but jamming problems during printing.

Have someone had same problem as me? How did you fixed it?

* Printer AlfaWise U30(bowden type) but it's no longer the same.
* Motherboard: MKS 1.4 Gen A4988 + DRV8825 Stepper drivers(no problems here)
* PID(Autotune), Calibrations and so on done correctly.
* Firmware latest marlin 1.1.9 (Tried bugfix but the same)
* Sofware for slicing PE Sli3er (Tried Ultimaker Cura with same model and same problem)

**Tags:** pla, diy-3d-printer, extrusion, petg
> **Comments:**
> **username_1**: Would you please provide some additional things to make it easier? You said Mk8, do you mean a Makerbot Mk8 Hotend? Or did you update to an all-metal hotend? What is your standard printing temperature? What is your retraction speed?  
> **username_2**: There are more settings to fight stringing, e.g. lower print temperature. PETG is more prone to stringing opposed to other types of plastic.  
> **username_0**: I wrote what I changed. I haven't touched the hotend. It is original what Alfawise had. They used makerbot mk8 hotend (I believe so) but not quite sure about. Because of that I ordered a new one and different. Alfawise doesn't like to share information about they products. The firmware wasn't open source like marlin. Sorry about the temperature or printing. For PLA is 200-220(recommended) So between those temp. It's still the same. Retract is default in sli3er (35mm/s) I tried from 25 to 50 and nothing... same  
> **username_0**: The most accurate link to hotend: https://www.amazon.com/Longer-Printer-Extruder-Creality-Alfawise/dp/B07PB2P5N1  
> **username_3**: Not an answe, but assuming PTFE is a bowden setup, you definitely need at least 4-6 mm of retraction to avoid stringing. 0.8-2mm is not going to cut it anywhere but a direct drive extruder, and I'd be doubtful that it's even really sufficient there. So you should try to fix this right.  
> **username_4**: I had same issue when switching to PETG.  
> **username_4**: With a Reprap x400 I could retract 6 mm, but this did not completely get rid of the stringing.  Retracting to 20 mm jammed the extruder at the first retract.  

---

## 1 answers

### Answer by username_5 on 2019-07-13. Score: 3

I had problems with jamming PETG due to retraction. My model had many retraction moves, such that the amount of filament used during a printing move was less than the retraction distance. I found that several trips through the feed gear flattened the filament, which caused two problems.

1. The flattened (or ovaled) filament had trouble fitting through the round holes and tubes, and
2. Since it was thinner, the filament was not gripped as tightly so there was less force pushing it.

I reduced my feed gear pressure and the problem stopped.

PETG is not as stiff as PLA. The multiple trips through mangle flattened it.


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