Does a filament sensor degrade/fail over time

[manuel42]

I've bought a cheap filamentsensor from aliexpress.
It seems to be a spring which creates contact if the filament is in, and no contact if the filament runs out.



Does the spring work when the filament is always in there, or do those sensors fail over time?

[beanflying]

Hi Manuel welcome to the forum. We do have an area for 3D printing if you want to take a look and a bit of a mini monster rambling thread on 3D printing in this section https://www.eevblog.com/forum/3d-printing/

On the filament sensor I had one fail on my CR-10S but I suspect in this case it was caused by me pulling filament out from the extruder through it (so backwards) and it damaged the blade and the switch failed. So I designed and built a new 3D printed housing to take another one I had on hand and included a Teflon guide for the filament while I was at it so I hope the lever is better protected.

As to failing over time there is very low voltage and current so it would be very unlikely for the contacts to fail, failure would likely be more like mine a mechanical issue.

[manuel42]

Hi and thanks for the welcome.
I wasn't sure about which forum, but i'll use the 3d one the next time.

For the sensor, i guess i'll just use it and would report back if there are any issues.

cheers

[Ian.M]

It appears to be based on a sub-miniature microswitch with a short lever arm operating its actuator.  As the actuator is protected from the friction and wear of the passing filament, and the switch wont be directly breaking significant current or voltage, the microswitch's service life is likely to be good.

However if mounted close to the extruder, as sub-miniature microswitches are rarely hermetically sealed, you may get a buidup of out-gassed plasticizer from the melted filament on its contacts, so if the controller doesn't provide sufficient wetting current for the switch, its likely to develop problems if the printer is either used very infrequently or is heavily used.   Reliability will also be impacted if the switch wiring is repeatedly flexed.

As the original poster (O.P.) in a topic, you have the ability to move it to another subforum, e.g  3D printing, as Beanflying suggested. See https://www.eevblog.com/forum/blog/what_s-this-move-topic-icon-all-about/

[manuel42]

I've moved the thread to 3D printing.

I'm actually going to mount the sensor a bit away from the printer.
Filament is on a shelf on the wall and the sensor is just in front of the filament. Then there is about one meter to the printer.
The idea is to send me a push notification to the phone and to have enough time to pause the print for filament changing.

edit: This sensor is not integrated in the 3d board, but rather connected to a standalone arduino.

[CatalinaWOW]

This type of sensor tends to be reliable.  But murphy can strike anywhere. 

A filament sensor seems a little like a solution looking for a problem to me.  When you start a print you should have a good idea of how much filament is still on the reel and take appropriate action at that time.  Filament is cheap enough that trying to utilize the last few centimeters is kind of pointless, and my personal experience with re-starting prints has not been good.  That leaves a break in the filament as the use case for one of these sensors.  Again, my personal history is zero problems with this issue.

[AmnevaR]

I don't use filament sensor too. Prusa slicer shows a length of the filament I'll need 
If a filament spool is close to the end before print, then I just count windings and multiply them by πD.
Number of windings X 3.14 X spool diameter

[manuel42]

I don't use filament sensor too. Prusa slicer shows a length of the filament I'll need 
If a filament spool is close to the end before print, then I just count windings and multiply them by πD.
Number of windings X 3.14 X spool diameter

I was not aware of the prusa slicer feature (I do have a mk3s) and i also did not know this neat trick.

I'm aware that this is an artificial problem to solve but if it works it might be handy.
Besides this, i just started out with electronics/microcontroller and do not have great understanding yet. This seemed to be a simple enough yet useful application to toy around.

[AmnevaR]

I'm aware that this is an artificial problem to solve but if it works it might be handy.
Besides this, i just started out with electronics/microcontroller and do not have great understanding yet. This seemed to be a simple enough yet useful application to toy around.

Yes, go for it! Looks like an interesting project!

I also often use my old phone as a camera to look after printer when I'm away from home. Things could go wrong when you least expect it

Volumetric characteristics in Prusa Slicer are pretty accurate. I think other slicers have similar features hidden somewhere too.

[CatalinaWOW]

In Cura meters of filament used appears in the lower right of the screen.  If you have entered the size and price of the reel it also displays the material cost of the print.

[manuel42]

Just a quick update. The sensor is in place and works so far.



I currently cannot send push notification since i'm still waiting for my wifi-arduino.
Also i'm using an empty spool as a filament guide on the printer and plan to print a dedicated guide instead.