Filament Change Flaw with runout  

RE: Filament Change Flaw with runout

From my understanding it should retract the remaining filament about a cm or so - enough so that you can grab it from the side sensor (where the spool holder is) and pull the remaining back out.......

RE: Filament Change Flaw with runout

Well this not works, as it really leaves only a few cm left 

RE: Filament Change Flaw with runout

Are you sure the side filament sensor is working properly then? Perhaps try recalibrating it.

RE: Filament Change Flaw with runout

Well it seems it is not working properly regarding the answers so far 😀 
I'll check that , thanks

Posted by: @john-3

Are you sure the side filament sensor is working properly then? Perhaps try recalibrating it.

RE: Filament Change Flaw with runout

I have the same problem. I think the extruder doesn't have enough force to push the filament back through the filament sensor during retraction, and instead, it starts grinding the filament as the extruder begins skipping.

RE:

Posted by: @ahrimaan

when you change filament when it runs out it purges some filament and then tell you to "remove Filament form the sensor".

So everytime i have to open the top lid, remove the PTFE Tube from the Nextruder and pull out the filament.
There must be a more elegant way of doing this.

This sounds like the side filament sensor has not detected the filament runout, and it only gets detected by the filament sensor in the Nextruder. In which case the Core One purges through the nozzle and then (I believe) complains that you should remove the filament from the side sensor. Where of course there is no filament, since it has already run out and it's just the side sensor malfunctioning.

A frequent cause of the side sensor getting stuck in "I see filament" mode is excessive friction on the little lever (which translates movement of the steel ball into movement of the flag that gets detected by the optical sensor). Favorite root cause: The magnet which sits inside this lever is actually a bit wider than the lever. If it sticks out too far on the lid-facing side of the lever, it will rub against the lid of the sensor housing once the lid is mounted.

To check and correct, you will need to remove the right side panel, remove the filament sensor from the panel, and open its lid. Make sure the magnet sticks out equally on both sides of the lever, about 0.5 mm each side.

RE: Filament Change Flaw with runout

Hi all , so I calibrated the sensor and both works correctly ...until the chamber heats up , then it shows always ON for the side sensor ..... I think I have to rebuild it again. 

RE: Filament Change Flaw with runout

If the sensor only gets stuck when the printer is warming up, the screw on the sensor lever, which must move freely, could be (and probably is) too tight. Try disassembling the sensor and loosening the screw a little. The assembly instructions also warn about this - just tighten it slightly.

RE: Filament Change Flaw with runout

RE: Filament Change Flaw with runout

I would love if they changed the logic here. Why do we have to rely on the side sensor only? 

I would like to have:
Filament runout detected on side sensor
Printer keeps printing until X mm of filament have been consumed (this should be less than the bowden length from the side sensor to the sensor on the nextruder)
Printer pauses and purges the remainder of the filament through the nozzle
You load new filament through the side sensor and into the nextruder
Nextruder purges the remnants of old filament through the nozzle and now only new filament is in the nozzle
Resume print

Right now it seems pretty cludgy and it's a pain to pull the filament, especially if it gets stuck. There's also no option to purge the filament through the nozzle, so if it gets stuck in the bowden tube I have to screw around with removing the bowden tube from the top of the nextruder during a print and risk having the printer lose position. 

This is a relatively easy software fix and could be written up in an afternoon. 

RE: Filament Change Flaw with runout

I wish Prusa would implement something like this: BTT SFS V2.0 Smart Filament Sensor that can detect snags or otherwise filament not moving during a print. 

RE: Filament Change Flaw with runout

They can. That's why they have the loadcell in the nozzle. If the filament gets snagged, the load on the nozzle drops, and it will pause. 

RE:

I found out that for me main problem is bent filament at the end - it's bent so that it can be inserted into a reel hole to be able to start winding when making it, that makes sense, but this sharp bend causes havoc, especially now that i have MMU3.  MMU unit's sensor does detect out of filament, but when pushing back this sharp bend prevents filament to go back into ptfe tube, so either it gets stuck with an error, or if i'm lucky it pops out at the side somewhere. I guess there's nothing that can be done regarding this, only "being there" when out of filament occurs and change it manually, or sometimes i just clip off that bent part (again, if i'm there...).

Hopefully indx system will solve this... ?

RE: Filament Change Flaw with runout

What I did last time is as the current filament is ending - I snipped the end so it was nice and straight, and then by hand pushed the new filament directly behind it - keep pushing all the way until the extruder grabs onto it - this way the printer doesn't know any different and continues printing as normal lol

Of course only works if you are at the printer during the time of current filament spool ending!

RE: Filament Change Flaw with runout

Posted by: @iftibashir

Of course only works if you are at the printer during the time of current filament spool ending!

Or you can use one of these: S1 Plus - Automatic Filament Loader

RE: Filament Change Flaw with runout

Posted by: @hyiger

 

Posted by: @iftibashir

Of course only works if you are at the printer during the time of current filament spool ending!

Or you can use one of these: S1 Plus - Automatic Filament Loader

Yeh, I did come across this previously, but I'm a cheapskate so stuck with the manual method! lol

RE: Filament Change Flaw with runout

For all with mmu3 “bowden speed loader” from printables is the best you can print. I can’t imagine loading filament without it…

RE: Filament Change Flaw with runout

Like I said, easy fix is to just purge the remaining filament through the nozzle (this is the logic I use on my custom printers). The filament is garbage anyway, what difference does it make if it's a 1.75mm piece, or a pile of plastic poop. At least with the poop option, I'm not cursing the printer out. 

RE: Filament Change Flaw with runout

Posted by: @krieger

Like I said, easy fix is to just purge the remaining filament through the nozzle (this is the logic I use on my custom printers). The filament is garbage anyway, what difference does it make if it's a 1.75mm piece, or a pile of plastic poop. At least with the poop option, I'm not cursing the printer out. 

Stefan at CNC kitchen actually tested filament made from cow poop (mixed into the plastic).