<p>You'd have to ensure that the joining portion of the two filaments do not "bloom" or increase in diameter, which would happen if unconstrained at the melting and joining time. Alignment is also critical, otherwise you have a varying diameter from one color to the next at the point of join.</p>

<p>There's an item on ebay which is precision drilled and has precision machined mating surfaces to ensure alignment of the filament. The filament is extended through the two components, heated (in the case of the video, with a match) and the two metal parts are pushed together. The joining of the metal parts also cuts away the excess bulge of the melted filament, ensuring correct diameter.</p>

<p>In the case of the above item, the joining devices have to be threaded with the filament prior to the joining process and then have to be threaded off the filament by pushing them the entire length of the filament.</p>

<p>This would be okay if one were joining short lengths only. Consider how much fun it isn't to have to slide these two pieces over an entire full spool of filament.</p>

<p>A split device which would enable one to un-latch or otherwise open a clamshell to release the filament would require much more challenging machining to achieve the necessary precision, which is probably why we don't see such a product.</p>

CC BY-SA 3.0
2016-06-15T20:05:06.527Z
2016-06-15T20:05:06.527Z
fred_dot_u
<p>There is a device which can do what fred_dot_u describes in his otherwise explanatorily good answer: the <a href="http://www.i3dinno.com/easywelder-en-p186486.html" rel="nofollow">easywelder</a>, made by I3D Inno.</p>

<p>It fixes the filament in a separate part so that the faces are adjoined perpendicularly and then heats the joint electrically with a device that at first sight reminds me of a hair straightening iron.</p>

<p>I am not sure about the joint quality this machine produces, but I am skeptical whether the it is good enough for high accuracy 3d printing. Especially if you take the history of the device into account (he wanted to create a custom O-ring from Ninjaflex), which the inventor shortly describes on this instructable: <a href="http://www.instructables.com/id/Welding-tool-for-plastic-filaments" rel="nofollow">http://www.instructables.com/id/Welding-tool-for-plastic-filaments</a></p>

CC BY-SA 3.0
2016-06-15T20:38:37.077Z
2016-06-15T20:38:37.077Z
kamuro
<p>Here is a neat method I came up with:
- cut both ends diagonally
- insert them in a piece of heat-shrink tubing, making sure the diagonal cuts overlap
- protect everything but the overlap with Kapton tape
- heat the overlap with a heat gun. 
- you will need to monitor and experiment with the temperature. too much heat will deform and bubble the filament, too less heat will  result in a poor join
- use a multimiter with temperature probe.</p>

<p>How it works ?</p>

<p>The heat shrink tubing encloses the filament ends and also pushes them together when it shrinks. The diagonal cuts increase the joint area. Results are super strong and seamless joints. You might need to do a little sanding until you establish the right temperature for your setup.</p>

<p>I made a video how to do it :
<a href="https://youtu.be/eJeU9lXiQPE" rel="nofollow noreferrer">https://youtu.be/eJeU9lXiQPE</a></p>

CC BY-SA 3.0
2017-07-16T01:47:33.377Z
Rather than just posting a video link, it is better to describe answer and provide the link for more detail on the technique.
markshancock
CC BY-SA 3.0
2017-07-19T12:03:43.400Z
Nice method but it takes so much time it doesn't seem worth it to spare a few meters of filament. Time is money :-)
ON5MF Jurgen
CC BY-SA 3.0
2017-07-15T18:03:52.690Z
2017-07-19T11:04:38.117Z
2017-07-19T11:04:38.117Z
starlino
<p>idea is good and i know for sure many are working on it but if you want this to work smoothly you may need to fix the device (that is joining two filaments) somewhere near your cutter assembly (if any)arranged to cut the filament...this is the another way to perform the task automatically but you can do it separately with devices available to cut and join the two filaments together. </p>

<p>links below:</p>

<p><a href="http://diy3dprinting.blogspot.in/2014/07/fuse-clamp-filament-welding-device-for.html" rel="nofollow noreferrer">http://diy3dprinting.blogspot.in/2014/07/fuse-clamp-filament-welding-device-for.html</a></p>

CC BY-SA 3.0
2017-07-19T13:52:09.907Z
Please describe the process rather than linking it, links can become broken and information lost.  Links are fine as long as you describe the process here.  Right now I have no idea what your answer says.
tjb1
CC BY-SA 3.0
2017-07-19T12:57:47.517Z
2017-07-19T12:57:47.517Z
user7830
<p>I haven't tried this but it is something I have thought about. The simplest way to try this that I could think of was to try cutting the ends flat and then using a soldering iron or just the printers printing nozzle to melt the ends and then quickly press them together, then you could sand the filamelt to try and clean up the join. </p>

<p>I think what would work better than trying to get the width perfect would be to make sure your printer is doing infill when it hits the join so over or under extrusion wont matter as much or have the printer move to the side of the print and extrude in thin air while getting past the join. I have done this when swapping filaments during a print by pausing the printer, and changing the filament.</p>

CC BY-SA 3.0
2016-06-20T05:12:58.353Z
2016-06-20T05:12:58.353Z
user802599
<p>Is it possible to connect two pieces of 1.75 mm filament end to end, with no change in width? I am asking the question because I am interested in creating a multi-filament feeder to a single extruder, and I am curious about the process of changing filament while the 3-d printer extruder continues uninterrupted. My current best-guess at the optimal solution is to someone 'cut' one end of the filament and 'melt' it to the end of another filament.</p>

<filament><extruder><extrusion>
How to connect filament end-to-end?
J. Roibal - BlockchainEng
# How to connect filament end-to-end?

(Asked by: username_0 on 2016-06-15)

Is it possible to connect two pieces of 1.75 mm filament end to end, with no change in width? I am asking the question because I am interested in creating a multi-filament feeder to a single extruder, and I am curious about the process of changing filament while the 3-d printer extruder continues uninterrupted. My current best-guess at the optimal solution is to someone 'cut' one end of the filament and 'melt' it to the end of another filament.

**Tags:** filament, extruder, extrusion

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## 5 answers

### Answer by username_1 on 2016-06-15. Score: 5

You'd have to ensure that the joining portion of the two filaments do not "bloom" or increase in diameter, which would happen if unconstrained at the melting and joining time. Alignment is also critical, otherwise you have a varying diameter from one color to the next at the point of join.

There's an item on ebay which is precision drilled and has precision machined mating surfaces to ensure alignment of the filament. The filament is extended through the two components, heated (in the case of the video, with a match) and the two metal parts are pushed together. The joining of the metal parts also cuts away the excess bulge of the melted filament, ensuring correct diameter.

In the case of the above item, the joining devices have to be threaded with the filament prior to the joining process and then have to be threaded off the filament by pushing them the entire length of the filament.

This would be okay if one were joining short lengths only. Consider how much fun it isn't to have to slide these two pieces over an entire full spool of filament.

A split device which would enable one to un-latch or otherwise open a clamshell to release the filament would require much more challenging machining to achieve the necessary precision, which is probably why we don't see such a product.


---

### Answer by username_2 on 2016-06-15. Score: 3

There is a device which can do what fred\_dot\_u describes in his otherwise explanatorily good answer: the [easywelder](http://www.i3dinno.com/easywelder-en-p186486.html), made by I3D Inno.

It fixes the filament in a separate part so that the faces are adjoined perpendicularly and then heats the joint electrically with a device that at first sight reminds me of a hair straightening iron.

I am not sure about the joint quality this machine produces, but I am skeptical whether the it is good enough for high accuracy 3d printing. Especially if you take the history of the device into account (he wanted to create a custom O-ring from Ninjaflex), which the inventor shortly describes on this instructable: <http://www.instructables.com/id/Welding-tool-for-plastic-filaments>


---

### Answer by username_3 on 2017-07-15. Score: 1

Here is a neat method I came up with:
- cut both ends diagonally
- insert them in a piece of heat-shrink tubing, making sure the diagonal cuts overlap
- protect everything but the overlap with Kapton tape
- heat the overlap with a heat gun.
- you will need to monitor and experiment with the temperature. too much heat will deform and bubble the filament, too less heat will result in a poor join
- use a multimiter with temperature probe.

How it works ?

The heat shrink tubing encloses the filament ends and also pushes them together when it shrinks. The diagonal cuts increase the joint area. Results are super strong and seamless joints. You might need to do a little sanding until you establish the right temperature for your setup.

I made a video how to do it :
<https://youtu.be/eJeU9lXiQPE>

> **Comments:**
> **username_4**: Rather than just posting a video link, it is better to describe answer and provide the link for more detail on the technique.  
> **username_5**: Nice method but it takes so much time it doesn't seem worth it to spare a few meters of filament. Time is money :-)  

---

### Answer by username_6 on 2017-07-19. Score: 0

idea is good and i know for sure many are working on it but if you want this to work smoothly you may need to fix the device (that is joining two filaments) somewhere near your cutter assembly (if any)arranged to cut the filament...this is the another way to perform the task automatically but you can do it separately with devices available to cut and join the two filaments together.

links below:

<http://diy3dprinting.blogspot.in/2014/07/fuse-clamp-filament-welding-device-for.html>

> **Comments:**
> **username_7**: Please describe the process rather than linking it, links can become broken and information lost.  Links are fine as long as you describe the process here.  Right now I have no idea what your answer says.  

---

### Answer by username_8 on 2016-06-20. Score: 0

I haven't tried this but it is something I have thought about. The simplest way to try this that I could think of was to try cutting the ends flat and then using a soldering iron or just the printers printing nozzle to melt the ends and then quickly press them together, then you could sand the filamelt to try and clean up the join.

I think what would work better than trying to get the width perfect would be to make sure your printer is doing infill when it hits the join so over or under extrusion wont matter as much or have the printer move to the side of the print and extrude in thin air while getting past the join. I have done this when swapping filaments during a print by pausing the printer, and changing the filament.


---

