<p>Shoutout to @0scar for posting a photo of the filament sensor, that was super helpful. Also thanks to everyone else who pointed me to the filament sensor and resources around that.</p>

<p>I also tracked down <a href="https://www.printer3d.org/3d-printers/alfawise/alfawise-u20-large-format-3d-printer-review.html" rel="nofollow noreferrer">this review</a> which had great information around my printer's filament sensor as well. It turns out that the hole that goes to the sensor is way too big and there's a lot of play with the filament. As I jiggled the filament up &amp; down I could hear the sensor clicking on &amp; off, clearly indicating that if the angle of entry of the filament was too low, the sensor would not be depressed and this would continue to be a problem.</p>

<p>So for my next print, I did what that reviewer suggested and simply unscrewed the sensor &amp; taped it so it would not stop my print. My print was unsuccessful for other reasons (under-extrusion/failed to adhere to the build plate ), but at least I think I've figured out what's going on with my filament sensor. Thanks again everyone!</p>

CC BY-SA 4.0
2019-07-11T06:19:57.513Z
the clicking tells us it's mechanical
Trish
CC BY-SA 4.0
2019-07-13T01:08:42.567Z
Yes I agree, it's a mechanical filament sensor, not optical
steve
CC BY-SA 4.0
2019-07-10T23:40:09.657Z
2019-07-12T21:59:28.410Z
2019-07-12T21:59:28.410Z
steve
<h2>Background:</h2>

<p>I have an Alfawise U20 (CR10 clone) and am still somewhat of a noob, though I've been learning as much as quickly as time will allow.</p>

<p>The Alfawise U20 has "out-of-filament" detection, though I'm not 100&nbsp;% certain how it works. I think that there's a roller across from the toothed knob that drives the filament into the Bowden tube, and if the roller doesn't roll, that means the filament has run out(?).</p>

<p><a href="https://i.sstatic.net/ZBVMv.jpg" rel="nofollow noreferrer" title="Alfawise U20 extruder and filament run-out sensor"><img src="https://i.sstatic.net/ZBVMv.jpg" alt="Alfawise U20 extruder and filament run-out sensor" title="Alfawise U20 extruder and filament run-out sensor"></a></p>

<p>I've become fairly proficient printing with PLA but this is the first time I've tried printing with PETG.</p>

<h2>Problem:</h2>

<p>Almost immediately after starting a print, the printer pauses the print and displays message "Out of filament. Would you like to change filament?" There's not even time for the toothed knob to click, which I've seen when trying to print PLA too fast/too cold.</p>

<p>If I manually extrude some filament, it seems to work fine. When I resume the print, it will print for anywhere between ~2 seconds &amp; ~5 minutes before pausing again, prompting me to change filament.</p>

<p>I'm printing at 240&nbsp;&deg;C. I've seen opinions vary pretty far &amp; wide wrt how hot to print PETG, with some people saying you can print successfully as cold as 215&nbsp;&deg;C, and others saying you should crank it up to 250+&nbsp;&deg;C. <a href="https://rads.stackoverflow.com/amzn/click/com/B07QKPVBQ8" rel="nofollow noreferrer" rel="nofollow noreferrer">This filament</a> is rated for 230-250&nbsp;&deg;C extrusion.</p>

<p>Again, manually extruding filament works fine. No slippage, no clicking. Smooth extrusion.</p>

<p>I've read that PETG is extremely hygroscopic. Could my problem be caused by the filament having absorbed too much water? How would I even determine if this was the cause?</p>

<p>What else could be causing my problem? I've read some printers' "out of filament" detection have problems with translucent filaments?</p>

CC BY-SA 4.0
2019-07-09T03:20:19.013Z
Is your filament translucent? If so I suspect that's your problem. My understanding is that most "out of filament" detectors are optical.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2019-07-09T06:13:12.000Z
@R.. it's semi-transparent. There's a link to it in the OP
steve
CC BY-SA 4.0
2019-07-09T08:20:13.187Z
@R.. That was my first guess also. W.r.t. being gyroscopic, my largest printer is located in our laundry room, where laundry dries, I have my 2.2 kg PETG spools uncovered, no problem whatsoever.
0scar
CC BY-SA 4.0
2019-07-09T09:25:45.557Z
What kind of filament sensor do you have? Is it optic or mechanical? Please share a photo.
Trish
CC BY-SA 4.0
2019-07-09T14:41:43.487Z
Easy test for optical vs mechanical:  if it's mechanical then a sensor has to be physically touching the filament.  If you can't tell that,  then slide a piece of glass or clear plastic into that slot and see whether the error is reported.
Carl Witthoft
CC BY-SA 4.0
2019-07-09T14:46:13.973Z
Online reviews indicate that many of the firmware updates cause new bugs. I dunno whether your version generates spurious 'out of filament' notifications, but if you can find a forum page or two dedicated to this model, that might be the best place to ask.
Carl Witthoft
CC BY-SA 4.0
2019-07-09T14:49:44.623Z
Since it could be a bug, see if it reports that there is filament when there is no filament installed.
user77232
CC BY-SA 4.0
2019-07-09T16:23:26.823Z
@Trish I'm not sure what kind of filament sensor it is... I'm not even sure what they look like or where they're typically mounted 
steve
CC BY-SA 4.0
2019-07-09T16:24:25.303Z
@CarlWitthoft I haven't upgraded the firmware since I got it this past December. I've been wondering if I should try upgrading it, if that would fix it but now it sounds like maybe I leave it as-is 
steve
CC BY-SA 4.0
2019-07-09T16:33:12.563Z
I just noticed @0scar helpfully added a photo of the filament sensor!! Thank you!  I'll go investigate on my unit. I can't tell from the photo if it's optical or a simple switch, but it looks fancy soooo maybe optical?
steve
<extruder><extrusion><petg>
Printing with PETG, printer says it's out of filament when it clearly is not
steve
# Printing with PETG, printer says it's out of filament when it clearly is not

(Asked by: username_0 on 2019-07-08)

## Background:

I have an Alfawise U20 (CR10 clone) and am still somewhat of a noob, though I've been learning as much as quickly as time will allow.

The Alfawise U20 has "out-of-filament" detection, though I'm not 100 % certain how it works. I think that there's a roller across from the toothed knob that drives the filament into the Bowden tube, and if the roller doesn't roll, that means the filament has run out(?).

[![Alfawise U20 extruder and filament run-out sensor](https://i.sstatic.net/ZBVMv.jpg "Alfawise U20 extruder and filament run-out sensor")](https://i.sstatic.net/ZBVMv.jpg "Alfawise U20 extruder and filament run-out sensor")

I've become fairly proficient printing with PLA but this is the first time I've tried printing with PETG.

## Problem:

Almost immediately after starting a print, the printer pauses the print and displays message "Out of filament. Would you like to change filament?" There's not even time for the toothed knob to click, which I've seen when trying to print PLA too fast/too cold.

If I manually extrude some filament, it seems to work fine. When I resume the print, it will print for anywhere between ~2 seconds & ~5 minutes before pausing again, prompting me to change filament.

I'm printing at 240 °C. I've seen opinions vary pretty far & wide wrt how hot to print PETG, with some people saying you can print successfully as cold as 215 °C, and others saying you should crank it up to 250+ °C. [This filament](https://rads.stackoverflow.com/amzn/click/com/B07QKPVBQ8) is rated for 230-250 °C extrusion.

Again, manually extruding filament works fine. No slippage, no clicking. Smooth extrusion.

I've read that PETG is extremely hygroscopic. Could my problem be caused by the filament having absorbed too much water? How would I even determine if this was the cause?

What else could be causing my problem? I've read some printers' "out of filament" detection have problems with translucent filaments?

**Tags:** extruder, extrusion, petg

> **Comments:**
> **username_1**: Is your filament translucent? If so I suspect that's your problem. My understanding is that most "out of filament" detectors are optical.  
> **username_0**: @R.. it's semi-transparent. There's a link to it in the OP  
> **username_2**: @R.. That was my first guess also. W.r.t. being gyroscopic, my largest printer is located in our laundry room, where laundry dries, I have my 2.2 kg PETG spools uncovered, no problem whatsoever.  
> **username_3**: What kind of filament sensor do you have? Is it optic or mechanical? Please share a photo.  
> **username_4**: Easy test for optical vs mechanical:  if it's mechanical then a sensor has to be physically touching the filament.  If you can't tell that,  then slide a piece of glass or clear plastic into that slot and see whether the error is reported.  
> **username_4**: Online reviews indicate that many of the firmware updates cause new bugs. I dunno whether your version generates spurious 'out of filament' notifications, but if you can find a forum page or two dedicated to this model, that might be the best place to ask.  
> **username_5**: Since it could be a bug, see if it reports that there is filament when there is no filament installed.  
> **username_0**: @username_3 I'm not sure what kind of filament sensor it is... I'm not even sure what they look like or where they're typically mounted   
> **username_0**: @username_4 I haven't upgraded the firmware since I got it this past December. I've been wondering if I should try upgrading it, if that would fix it but now it sounds like maybe I leave it as-is   
> **username_0**: I just noticed @username_2 helpfully added a photo of the filament sensor!! Thank you!  I'll go investigate on my unit. I can't tell from the photo if it's optical or a simple switch, but it looks fancy soooo maybe optical?  

---

## 1 answers

### Answer by username_0 on 2019-07-10. Score: 2

Shoutout to @username_2 for posting a photo of the filament sensor, that was super helpful. Also thanks to everyone else who pointed me to the filament sensor and resources around that.

I also tracked down [this review](https://www.printer3d.org/3d-printers/alfawise/alfawise-u20-large-format-3d-printer-review.html) which had great information around my printer's filament sensor as well. It turns out that the hole that goes to the sensor is way too big and there's a lot of play with the filament. As I jiggled the filament up & down I could hear the sensor clicking on & off, clearly indicating that if the angle of entry of the filament was too low, the sensor would not be depressed and this would continue to be a problem.

So for my next print, I did what that reviewer suggested and simply unscrewed the sensor & taped it so it would not stop my print. My print was unsuccessful for other reasons (under-extrusion/failed to adhere to the build plate ), but at least I think I've figured out what's going on with my filament sensor. Thanks again everyone!

> **Comments:**
> **username_3**: the clicking tells us it's mechanical  
> **username_0**: Yes I agree, it's a mechanical filament sensor, not optical  

---

