Constant request to change filament even when sensor detects filament.
 
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Nartus
(@nartus)
New Member
Constant request to change filament even when sensor detects filament.

Hi all,

So I have had a MK3S+ for a few years now and I have encountered a strange problem.

During recent prints I have had the printer request that the filament be unloaded and reloaded. This issue can occur once in a while or several times in a row when the filament is loaded from a previous request. I have checked the guides seen at the following links: 

https://help.prusa3d.com/article/mk3s-keeps-prompting-filament-change_2129

https://help.prusa3d.com/article/ir-filament-sensor-troubleshooting-mk2-5s-mk3s_112226

During testing of the sensor, the Sensor Info screen reports 1 when the filament is there and 0 when its not, like it should. I have also watched the Sensor Info screen while a print is going and when it requests a filament change the filament sensor does not change to 0. It is possible for a brief moment it changes to 0. During one of my observations I did see the sensor report a 0 before going back to 1. In all other instances of my observation I never saw it go to 0.

I am sure that its not the filament having defects as its the same spool of filament I have printed with before this issue appeared. The only thing I can guess is that the filament sensor has gone faulty or when the printer is moving in a certain way the sensor reports a momentary 0 quicker then I can see it. I have also taken the filament and shaken it lightly to see if I get the behavior to happen with no luck.

Any advice would be appreciated.

Thanks

Napsal : 03/08/2022 1:54 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
RE: Constant request to change filament even when sensor detects filament.

this could be as simple as a faulty Filament Sensor wire. 

I am changing my filament sensor wire at the moment, and have only taken a break, to find some cable ties to complete the job

as the printer moves it flexes the wires repeatedly, and this can cause metal fatigue, leading to intermittent contact and the error you are seeing. 

you might be able to observe the setting on the LCD, and move the cable bundle behind the X carriage, to see the value change.

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Napsal : 03/08/2022 2:04 pm
Nartus
(@nartus)
New Member
Topic starter answered:
RE: Constant request to change filament even when sensor detects filament.

Just gave the wire bundle a few shakes/ light bends  with no change on the sensor info. Its still possible that it might be the wire. I don't think I have a spare cable as this was a pre-constructed printer when I purchased it. I can order a new one and still print just without the sensor for the time being.

Napsal : 03/08/2022 2:13 pm
Diem
 Diem
(@diem)
Illustrious Member

This can also be a loose, vibrating, plug at the Einsy end.  A quick check that it's firmly home is worthwhile.

Cheerio,

Napsal : 03/08/2022 8:40 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
RE: Constant request to change filament even when sensor detects filament.

I have been printing without the filament sensor for ages. 

I got my new cable from Zaribo, in England. 

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Napsal : 03/08/2022 8:43 pm
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