Running out of filament  

Re: Running out of filament

Hi Bernard, there are many variables

in an ideal situation, the end of the filament will not be anchored to the reel, and the filament sensor will be turned on and working perfectly...

when the printer gets to the roll end the sensor will trigger the filament runout process and the printer will move the extruder out of the way, and bleep, to let you know it's lonely...

you will attend immediately, press the control knob on the lcd panel, and the printer will unload the stub of the old filament, beep again and the LCD will instruct you to remove the filament.

you remove the empty reel, and put it on one side, to ponder it's fate later.

(A) you take your next part reel, mount it on the reel holder, find the end of the filament, trim it neatly at an angle, insert the end into the extruder, and follow the instructions on the LCD...

if you didn't respond immediately, the printer may bleep incessantly (or not) depending on your chosen settings on the lcd...

after about 30 minutes, the extruder heater will shut down but the heatbed will retain its normal temperature...

if this has happened, you will have to wait for the extruder to reheat, after initiating the filament change process, don't go away, wait for the filament to unload, and continue as above!

when the extruder tries to unload, there are two primary failure modes:-

(1) in the first, the filament does not get pushed out of the top of the extruder, but jams inside, because the tight curvature of the filament end causes it to miss the outlet...
in this case, open the bondtech idler door, reach in with a pair of long nose pliers, grab the filament above the bondtech gear, and press down, expelling some of the filament out o the nozzle, if you can't yet see the end of the filament in the bondtech housing, repeat, until the end of the filament becomes visible,then, still using the long nose pliers, pull the end of the filament out of the bondtech hatch, clearing the extruder.

refit the tension screws and springs, adjust to your preferred setting, and goto (A)

(2) in the second case, the filament sensor triggers late, and the end of the filament has passed the bondtech gears, and cannot be unloaded mechanically...
in this case, open the bondtech idler door, reach in with a pair of long nose pliers, grab the end of the filament and pull it out of the bondtech hatch, clearing the extruder.

of course, there is every chance that the end of the filament has been poked through a hole in the reel, and bent over
in the worst case, this can prevent the filament coming off the reel, and :-
* the tension of the bondtech gears pulling may damage the spool holder.
* the tension may break the filament and the bent end may jam in the top of the extruder... see information above
* the tension may lift the extruder and x axis, causing substandard extrusion... deal with this as appropriate...

Goto (A)

if I am around when the filament gets to the last layer, I try to locate the end of the filament, and cut a short length off with the aim of making the reel end process as painless as possible if you can find, and trim the end of the filament, it's also a good idea to try and straighten the last few centimeters, to aid unloading later...
whichever mode occurs, you will hopefully clear the problem, and the extruder will squirt out some waste filament... RESIST THE TEMPTATION TO PULL IT OFF THE NOZZLE...
The display will ask if the colour is clear? let's assume the filament colour is clear , at this point, grab the waste pile with your pliers and press the button to confirm that all, is well, this will cause the extruder to squirt a little more filament out, and then continue with the print. the waste pile will break off the extruder and remain on your pliers

if the filament doesn't load properly, use the other options on the lcd screen, to feed more filament through, or reload the filament, as appropriate

apart from that it;s generally easy peasy

hope this makes sense,

regards Joan

Re: Running out of filament

Wish this had been posted a few days ago, I didn't realise about the second squirt and had already broken off the first extrusion, just happened to be on a critical part of the print as well!.

So now, as Joan states, I let it extrude, but don't remove the strand, but get hold of it, wait for the head to start to move back towards the print and it does its second purge, then tug the strand which pulls it clean away from the nozzle, just before the printing re-commences, this way you get a clean continuation.

Re: Running out of filament

of course, there is every chance that the end of the filament has been poked through a hole in the reel, and bent over
in the worst case, this can prevent the filament coming off the reel, and :-
* the tension of the bondtech gears pulling may damage the spool holder.
* the tension may break the filament and the bent end may jam in the top of the extruder... see information above
* the tension may lift the extruder and x axis, causing substandard extrusion... deal with this as appropriate...

Support has told me that this is why my filament sensor failed. They said the hook on the end of the roll damaged the sensor as it passed. I now do as you do Joan; Clip the hook off once enough filament has unspooled and I can see it.

Re: Running out of filament

Interesting, because I have experienced it and it didn't work as you described. [these problems on another thread..] BUT: I put in a new reel of PLA, to ensure that I didn't run out, and started the print - something that takes about 50 hrs and that I had printed before with not problem]. The next morning I went up to check and found the extruder moving around in mid air with about 1.5" of empty space between it and the print, still happily not-printing along.

What happened was that the PLA *broke* and apparently ran out and the extruder didn't notice and just kept chugging along. Do I correctly understand that my printer *should* have stopped when the filament broke and it ran out? Since it didn't, is that something I should worry about?

Thanks! /bernie\

Re: Running out of filament

It is my understanding that if you have your filament sensor turned on, it should have detected that there was no filament and paused the print, asking you to reload the filament.

Check to see if you have the sensor turned on, under settings i believe from the LCD panel. If so I would check the wiring to make sure it is correctly connected.

Note that many people have probles with the sensor and turn it off. I have not had that experience. I run mine all the time.

Re: Running out of filament

The printer *should* stop only if the filament sensor is turned on. Settings, filament sensor on.

There were a couple of updates where it was off by default, I am unsure if that changed or not, as the last offical update was end of Nov and I have turned mine on now....

Check if it is on or off....

RE: Running out of filament

@joantabb

Thank you for the very thorough response! This was very helpful. 

RE: Running out of filament

I don’t know about your particular case but if the filament snaps just after the filament sensor but above the bond tech gears (a very short potential distance) then the sensor would register the presence of filament but the gears wouldn’t be pulling it through so it would think it’s still printing fine. 
‘However given the general reported problems with the normal filament sensors it’s far more likely to be a printer issue. 

RE: Running out of filament

I know this is an old post, but I came here as part of investigating why I had a similar experience to what @BernieC describes - the printhead happily dancing away with no plastic being extruded.

In my case, a MK3S+ on latest firmware, v3.11.0, I had to both enable the filament sensor under settings, as well as telling the printer to pause when the sensor is triggered - i.e. toggling "Settings -> HW Setup -> FS Action" to "Pause".

Hope this helps somebody.