<p>In this case I would like to first recommend replacing your PTFE tube with a better quality product. Unfortunately, the quality:price ratio is as to be expected here. My reasoning:</p>

<p>PTFE has great thermal properties for a polymer, just like ABS. In fact, the <a href="https://en.wikipedia.org/wiki/Glass_transition" rel="nofollow noreferrer">glass-transition state</a> begins at relatively the same temperature between the two materials. ABS starts transitioning at <a href="https://www.matbase.com/material-categories/natural-and-synthetic-polymers/commodity-polymers/material-properties-of-acrylonitrile-butadiene-styrene-general-purpose-gp-abs.html#properties" rel="nofollow noreferrer">about 105&deg;C</a> and <a href="https://www.matbase.com/material-categories/natural-and-synthetic-polymers/engineering-polymers/material-properties-of-polytetrafluoroethylene-ptfe.html#properties" rel="nofollow noreferrer">about 127&deg;C</a> for PTFE.</p>

<p>However PTFE, traditionally, has a much higher <a href="https://en.wikipedia.org/wiki/Melting_point" rel="nofollow noreferrer">melting point</a> at about 327&deg;C as opposed to the usual 125&deg; we use in 3D printing.</p>

<p><strong>My Point</strong>: I think the hardware you currently have has low-quality PTFE.</p>

<p>PTFE can be recycled for re-use in other PTFE products. In recycled PTFE, you can lose a lot of the desired properties in the material (true for any material). This includes both the ideal "friction-less" and thermal resistance we need in 3D Printing.</p>

<p><strong>What I think happened:</strong> The higher print temperatures of ABS transitioned the PTFE into its glass-state. As the throat expands, the path of least resistance in the assembly is towards the extruder motor since the nozzle holds more pressure.</p>

<p><strong>I would not recommend "fixing" this problem with a retainer!</strong> By forcing the PTFE throat to stay in position, you could potentially force the PTFE to expand in other ways. Most likely resulting in constricting the filament, leading to grinding of filament on the drive gear and clogging of the nozzle. Worst case, you end up with gooey PTFE in your nozzle and/or around your retainer.</p>

CC BY-SA 3.0
2017-01-09T16:14:49.627Z
2017-01-09T16:14:49.627Z
tbm0115
<p>I believe the throat tube goes PTFE side (open end) down. That way the conical edge on the other end helps to guide the filament as it enters the tube. If it's PTFE side down, then the PTFE portion buts up against the nozzle which acts as a natural stop. It remains captured within the metal portion of the throat tube.</p>

CC BY-SA 4.0
2024-07-17T20:28:30.850Z
2024-07-17T20:28:30.850Z
Pᴀᴜʟsᴛᴇʀ2
<p>I see, you want to Block the tefflon tube from going Up and Out of the extruder. Yes I see no reason why you would not fid a nut cap. Drill a hole and have it work. There is likely a special nut cap with a pre existing hole in it already but I decided the keywords was asking for bad results on a work computer. </p>

<p>The only thing I can see happening is you will 1) possibly not have the clearance. 2) have a larger thermal mass.</p>

<p><a href="https://i.sstatic.net/UG4iP.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/UG4iP.jpg" alt="enter image description here"></a></p>

CC BY-SA 3.0
2017-01-09T16:15:03.723Z
2017-01-09T16:15:03.723Z
MakerModder
<p>I've tried using a throat with a PTFE tube, but encountered the problem described in this <a href="https://3dprinting.stackexchange.com/questions/904/teflon-tubing-in-nozzle-throat-coming-out">question</a>. It seems only a small amount of excess pressure in the extruder is enough to force out the inner tube. This makes me worry that with this particular part, I won't achieve a reliable configuration (and I'm experiencing some binding with the original plain steel throat, so a PTFE liner seems worth exploring).</p>

<p>I was wondering about the advisability of using a retainer to apply some pressure at the cold end - a nut with a washer soldered on maybe.</p>

<p>My goal is to prevent the teflon tube from rising up, so I can use this part and retain some resilience against excess extrusion pressure. I was assuming I had a slightly sub-standard throat part (in a pack of 6).</p>

<p>However, I now wonder if the problem was caused by too high a temperature (this is ABS filament) and maybe the teflon will be too soft to function as designed, so if I go back to PLA filament, maybe it is more likely to work without modification.</p>

<p><img src="https://i.sstatic.net/Kw6bM.jpg" width="200"> 
<a href="https://i.sstatic.net/Zj61nm.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/Zj61nm.jpg" alt="Extruder"></a></p>

CC BY-SA 3.0
2016-12-31T21:30:55.280Z
Why do you think you need this modification? I am not sure what you are trying to accomplish. That said so long as it's outside of the melt zone... else use metal.
MakerModder
CC BY-SA 3.0
2017-01-08T21:34:00.213Z
@SeanHoulihane I have temporarily closed this question as it is currently unclear what you are asking. I believe you're trying to prevent the teflon tube from being forced out, but I'm not sure. Seeing as how this question has been active for a little while now, I would recommend trying to make your question a little clearer. I will keep tabs for a few days and re-open if it becomes better. If I forget, don't be afraid to PM/ping myself or another moderator. Thank you.
tbm0115
CC BY-SA 3.0
2017-01-09T16:15:24.337Z
@Sean Thank you for updating your question. Hopefully our answers help.
tbm0115
<extruder>
Retainer for PTFE in throat
Sean Houlihane
# Retainer for PTFE in throat

(Asked by: username_0 on 2016-12-30)

I've tried using a throat with a PTFE tube, but encountered the problem described in this [question](https://3dprinting.stackexchange.com/questions/904/teflon-tubing-in-nozzle-throat-coming-out). It seems only a small amount of excess pressure in the extruder is enough to force out the inner tube. This makes me worry that with this particular part, I won't achieve a reliable configuration (and I'm experiencing some binding with the original plain steel throat, so a PTFE liner seems worth exploring).

I was wondering about the advisability of using a retainer to apply some pressure at the cold end - a nut with a washer soldered on maybe.

My goal is to prevent the teflon tube from rising up, so I can use this part and retain some resilience against excess extrusion pressure. I was assuming I had a slightly sub-standard throat part (in a pack of 6).

However, I now wonder if the problem was caused by too high a temperature (this is ABS filament) and maybe the teflon will be too soft to function as designed, so if I go back to PLA filament, maybe it is more likely to work without modification.

![](https://i.sstatic.net/Kw6bM.jpg)
[![Extruder](https://i.sstatic.net/Zj61nm.jpg)](https://i.sstatic.net/Zj61nm.jpg)

**Tags:** extruder
> **Comments:**
> **username_1**: Why do you think you need this modification? I am not sure what you are trying to accomplish. That said so long as it's outside of the melt zone... else use metal.  
> **username_2**: @SeanHoulihane I have temporarily closed this question as it is currently unclear what you are asking. I believe you're trying to prevent the teflon tube from being forced out, but I'm not sure. Seeing as how this question has been active for a little while now, I would recommend trying to make your question a little clearer. I will keep tabs for a few days and re-open if it becomes better. If I forget, don't be afraid to PM/ping myself or another moderator. Thank you.  
> **username_2**: @Sean Thank you for updating your question. Hopefully our answers help.  

---

## 3 answers

### Answer by username_2 on 2017-01-09. Score: 1

In this case I would like to first recommend replacing your PTFE tube with a better quality product. Unfortunately, the quality:price ratio is as to be expected here. My reasoning:

PTFE has great thermal properties for a polymer, just like ABS. In fact, the [glass-transition state](https://en.wikipedia.org/wiki/Glass_transition) begins at relatively the same temperature between the two materials. ABS starts transitioning at [about 105°C](https://www.matbase.com/material-categories/natural-and-synthetic-polymers/commodity-polymers/material-properties-of-acrylonitrile-butadiene-styrene-general-purpose-gp-abs.html#properties) and [about 127°C](https://www.matbase.com/material-categories/natural-and-synthetic-polymers/engineering-polymers/material-properties-of-polytetrafluoroethylene-ptfe.html#properties) for PTFE.

However PTFE, traditionally, has a much higher [melting point](https://en.wikipedia.org/wiki/Melting_point) at about 327°C as opposed to the usual 125° we use in 3D printing.

**My Point**: I think the hardware you currently have has low-quality PTFE.

PTFE can be recycled for re-use in other PTFE products. In recycled PTFE, you can lose a lot of the desired properties in the material (true for any material). This includes both the ideal "friction-less" and thermal resistance we need in 3D Printing.

**What I think happened:** The higher print temperatures of ABS transitioned the PTFE into its glass-state. As the throat expands, the path of least resistance in the assembly is towards the extruder motor since the nozzle holds more pressure.

**I would not recommend "fixing" this problem with a retainer!** By forcing the PTFE throat to stay in position, you could potentially force the PTFE to expand in other ways. Most likely resulting in constricting the filament, leading to grinding of filament on the drive gear and clogging of the nozzle. Worst case, you end up with gooey PTFE in your nozzle and/or around your retainer.


---

### Answer by username_3 on 2024-07-17. Score: 1

I believe the throat tube goes PTFE side (open end) down. That way the conical edge on the other end helps to guide the filament as it enters the tube. If it's PTFE side down, then the PTFE portion buts up against the nozzle which acts as a natural stop. It remains captured within the metal portion of the throat tube.


---

### Answer by username_1 on 2017-01-09. Score: 0

I see, you want to Block the tefflon tube from going Up and Out of the extruder. Yes I see no reason why you would not fid a nut cap. Drill a hole and have it work. There is likely a special nut cap with a pre existing hole in it already but I decided the keywords was asking for bad results on a work computer.

The only thing I can see happening is you will 1) possibly not have the clearance. 2) have a larger thermal mass.

[![enter image description here](https://i.sstatic.net/UG4iP.jpg)](https://i.sstatic.net/UG4iP.jpg)


---

