Clear all

Flexible filament not detected  

New Member
Flexible filament not detected

I'm experiencing a strage behaviour. Trying to print a combination of PETG and Flex (Extrudr 58D). I'm using MK3/MMU2S with latest firmware.

As soon as the Flex is to be printed, the printhead doesn't detect the filament properly (or this is what I assume). Filament comes pouring out, but the lateral movement (either the pre-print stripe in single mode) nor on the wiping tower starts. All I get is this.

I tried to follow other forum suggestions, but no change. To me it seems as if it's transported well but not recognized at the nozzle. The MMU2S detects and feeds fine.

Any suggestions?

Posted : 04/08/2020 11:49 am
Trusted Member
RE: Flexible filament not detected

Since flexible filament is squishier, it may not be pushing the extruder idler gear out far enough to trigger the filament sensor at the extruder. Remove the tubing to the extruder, bring up the sensor info menu, then loosen the screws on top to allow the IR sensor assembly to slide, then adjust it until it triggers when an actual piece of flexible filament is pushed in. I found it to be very touchy, and it might not be possible at all with sufficiently soft filament.

Posted : 04/08/2020 2:51 pm
New Member
RE: Flexible filament not detected


Hi, I had the same behavier with my MK3S too. After reliable work with TPU it starts after months. Loosen idler screw is mandantory while printing flex. In my Case this was not enough. I have to readjust the IR sensor. My hint is: when printing flex the Filament Sensor must be able to detect the Filament. This may Work with hard PLA but flex is squezed a little and this can bei a problem with flex. The printer is sill working with non- flex and cause a lot of headache.


Posted : 06/08/2020 9:37 am
Active Member
RE: Flexible filament not detected

Thanks for the tip, you have helped me a lot!

Posted : 04/09/2020 3:47 pm