FINALLY, #121 "Filament not detected" errors started to occur almost regularly!


Yes, just after filling the Flux Survey and mentioning I did not have a problem with Error #121, my Flux decided to prove me wrong!

I used my machine daily, since day one 6 month ago, without any #121 until recently. The errors started to appear gradually, one error every 2-3 prints, then progressed fairly rapidly. Recently to many errors started to occur in the same print, which I resolved, like many others, by turning off the filament detection in the Expert mode.

@proclaim, I checked the filament switch visually, it looks OK, no visible wear and tear. I am suspecting the error is caused by switch contact oxidation with time and ambient humidity. I am sure these cheap switches don’t use gold contacts and it does not take much oxidation to cause false switch readings. I am not sure how the Flux software is detecting the switch response but maybe a simple “timing loop” could prevent these false readings. If the software waits 2-3 seconds for more switch readings before putting out the error message, it would resolve most of the #121, since when I hit continue when the error message is up, the printing continues until the next #121.


I had a similarly problem few months ago. I saw a tip of the feeder mechanical switch was worn out and leaned on one side of a filament. They sent me a replacement filament feeder and I’m sure that will need to be replaced after few months of printing.


Mine is not worn out, the filament is pushing it in fully but I am now getting frequently #121. I am suspecting, there is no buffer between the switch non-contact response and the software error message output. If they had a 3 second delay before they sent the error message, the false responses would disappear, at least in my case since when the error comes up, all I do is hit “continue” and the print continues normally until the next #121.


Fixed mine (temporarily?) with a drop of superglue on the top.
Printed about 9 KG so far.


I’ll have to do a good inspection of the physical switch because my flux no longer detects the filament unless I partially depress the manual filament feed button.


Hopefully the upgrade incldues an optical sensor, instead of pressure switch.


Or you can disconnect and printing without it as I do and waiting for an Flux+ upgrade kit.


I disabled filament detection during printing on Monday, and yesterday I disabled it entirely to make filament loading less tedious. Still don’t know what Delta+ is, but I’m keen!


No it doesn’t … I was unaware about the little switch until it broke - now with filament detection disabled I don’t miss it. Nice to have, but not necessary.


yes i know i upgraded using the kit all seems working well. thanks for your response