Integrated Filament Run-out sensor

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ABH
Posts: 182
Joined: Sun Aug 14, 2016 7:31 pm

Integrated Filament Run-out sensor

Postby ABH » Sun Feb 25, 2018 10:08 am


Jetguy
Posts: 2697
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: Integrated Filament Run-out sensor

Postby Jetguy » Sun Feb 25, 2018 1:06 pm

Is that the "official" Rais3D one specific to an N1? I ask because it looks like that JST-XH style connector harness for a double sensor and the housing looks like the white painted styrene that they make much of the rest of the printer plastic with.

Looking in the filament entrance, can you confirm if there is a metal guide wear ring (could be like a brass eyelet or other material)?
N1 example detector.jpg

Compared to these commercially available detectors that also have them which are also injection molded housing and nice connectors at $10 for pair.
DSC05026.JPG

DSC05027.JPG

DSC05028.JPG


They are showing it detecting clear filament which was and is a concern with optical based sensors. It's a good video and does show it detecting what could be hard to detect filament.

Questions that also come up given how some problems that came up with Prusa's trick optical sensor that people have managed to damage with nothing more than filament. How protected are the tiny sensors inside the filament path? I know they are not the same as the Prusa one but again, for an $89 kit, how much "wear and tear" will these take? https://shop.prusa3d.com/forum/original ... 12849.html

ABH
Posts: 182
Joined: Sun Aug 14, 2016 7:31 pm

Re: Integrated Filament Run-out sensor

Postby ABH » Sun Feb 25, 2018 3:32 pm

This is my own design with optical sensors.
I use the P2 connector on the main board and I suspect Raise3D will do the same for their optical sensor offering.
P2.jpg
E.jpg


I bought the cheap ones with the metal inserts that you have shown.
It requires quite some force to pull the filament through it. Therefore I decided to create my own with less friction. The optical interrupter is not in contact with the filament. I don't know if the filament will create wear traces in the plastic; if it does I can print a new :-)

Jetguy
Posts: 2697
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: Integrated Filament Run-out sensor

Postby Jetguy » Sun Feb 25, 2018 4:36 pm

What sensor did you go with that was able to detect clear filament reliably?

ABH
Posts: 182
Joined: Sun Aug 14, 2016 7:31 pm

Re: Integrated Filament Run-out sensor

Postby ABH » Sun Feb 25, 2018 5:21 pm

I used a Sharp sensor with a Near Infra Red LED at 950 nm. If you mask half of the filament diameter and place the the optical sensor accurately, then you can rely on refraction to obtain a quite good discrimination.

Jetguy
Posts: 2697
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: Integrated Filament Run-out sensor

Postby Jetguy » Sun Feb 25, 2018 6:08 pm

ABH wrote:If you mask half of the filament diameter and place the the optical sensor accurately, then you can rely on refraction to obtain a quite good discrimination.


That's my concern with the filament path and tolerance of the unit. Filament tends to remain curved because it it spooled warm during manufacture and solidifies as coiled on the spool. When using it, this curve of being spooled is now the natural shape of the filament. This in turn puts stress on any path of the filament that is straight. That's why the off the shelf sensor I linked and we both had have some drag to the filament because the guides were for an absolutely straight filament and so curved filament off a spool is arching and rubbing. For the same reason, I know and have seen and examples of how filament can wear into a plastic guide in short order. If it wears, that may change the filament path alignment and if that is critical to sensing, then we get false triggering or missed fault detection.

I absolutely agree with you. If you print the housing on a DIY method and it wears, you print another housing. If you buy the $89 kit, and it wears, is Raise 3D going to either give you the STL (technically a downgrade from an injection molded housing) and have you reprint the housing, or send new housings if you see where I'm going.

I'm not trying to knock your design. I was unsure if the original video post was a beta unit of the Raise3D version since to date, it's not shipping and we have limited final details and real world usage of that proposed solution. Now that I know this is a DIY design and very nice I might add, that changes a lot of the details around it.

ABH
Posts: 182
Joined: Sun Aug 14, 2016 7:31 pm

Re: Integrated Filament Run-out sensor

Postby ABH » Sun Feb 25, 2018 9:18 pm

That's exactly true. It is the curved shape of the filament that creates the friction.
I have tried to mitigate the wear by extending the 4 mm PTFE tubing all the way down into the casing. That means that most of the "straightening" take place inside the PTFE tubing. The PTFE tubing last for a very long time and if it eventually gets worn, then it is easy to replace. In the spool end of the box I have a wider opening that allow for a curved shape of the filament, as shown on the photo.
Rev2.jpg

This means that there is only small forces needed to keep the filament in place around the sensor.
The version I filmed was the first version with a smaller opening. Luckily it is so that if you feel a large friction then that means large wear, if there is almost no force needed to pull the filament through that means less wear. I feel very little friction, so I believe it can last for some time :)

Jetguy
Posts: 2697
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: Integrated Filament Run-out sensor

Postby Jetguy » Mon Feb 26, 2018 12:12 am

BTW, really nice print quality. I didn't think the one in the video was printed. Maybe it's the angle or just it's video, but I didn't see a single layer line or infill line in that shot. Only in the picture you posted of the tubes details, then you can see it's 3D printed.


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