Problems unloading filament? FW 4.0.1  

RE: Problems unloading filament? FW 4.0.1

I have the same problem. I've been to using the next filament as a pusher and then purge for 5 minutes to get new filament loaded since I can't find a way to get the old filament out. Next time, I'll try to just do a warm pull after disabling the steppers.

RE: Problems unloading filament? FW 4.0.1

glad it's not just me pressing the wrong button.   I've found if I purge first, then unload it works and I'm able to remove the filament.  I personally think it's 'Ramming' in the wrong direction.

RE: Problems unloading filament? FW 4.0.1

Same problem here.

RE: Problems unloading filament? FW 4.0.1

Just powered off, then on since flashing and now it won't home correctly. Looks like the pinda probe is sensing fresh air 🙁 

Does anyone know how to downgrade the firmware? 

RE: Problems unloading filament? FW 4.0.1

Same here.  With mine it seems that when the extruder retracts the filament, it does not produce a clean tip.  The resulting knob gets stuck at the entrance to the PTFE tube.  Firmware upgrade and downgrade made no difference when I tried it with respect to this issue.

RE: Problems unloading filament? FW 4.0.1

Having the same issue

RE: Problems unloading filament? FW 4.0.1

There is no issue for this on Git yet, if you have this issue, please report it 🙂
- https://github.com/prusa3d/Prusa-Firmware-Buddy/issues

RE: Problems unloading filament? FW 4.0.1

With a few more tests, it seems that ramming may be chewing up the filament, making the unload action fail.

RE: Problems unloading filament? FW 4.0.1

all this about warm pull and using next as pusher seems fine,   but what about color change mid-print?

can't do anything there, I try to pause and it just sits there.

just a tad bit upset with this printer, along with poor layer quality, inability to color change and the what next I am not impressed.

        I have a 2.5s and a 3 so it isn't like this is my first go round

RE: Problems unloading filament? FW 4.0.1

@cdrskullbu

Your pinda probably died like mine did 3 days in. Mesh leveling in the air and wont move down in Z direction. Trying cutting all the zip ties and see if there is any undue stress on the Minda wire. When I got my replacement it worked straight away. I did read that another person had the same problem and they found a tie that was too tight and it started working again after he loosened it.

RE: Problems unloading filament? FW 4.0.1

Not sure if this is a filament related thing or firmware but I've been having issues unloading filament too. Seems like the tolerance of the little brass things that squeeze the PTFE between the hotend and the extruder often times dont let thicker/textured filament to pass easily. I've had some matte protopasta break off and a little bit of filament get stuck in the tube.  

With regards to ramming I just tested an unload. It initially rams in the opposite direction - almost like a retraction, then it rams properly and then it unloads. Not sure if the first initial retraction is new or not.

RE: Problems unloading filament? FW 4.0.1

Until the ramming / unloading is corrected, I've been slowing manually pushing the filament through the hotend then quickly pulling the filament out. this softens the end enough that it deforms to fit the PTFE tube. It seems the problem is just about dialing in the speed/force required to unload.

RE: Problems unloading filament? FW 4.0.1

Downgrading is possible, perhaps that will fix it.

https://forum.prusa3d.com/forum/general-discussion-announcements-and-releases/guide-how-to-downgrade-your-prusa-mini-firmware/

RE: Problems unloading filament? FW 4.0.1

I have found that if I run a print and dont unload the filament immediately after the print finishes I cant just do a unload filament. I will get a filament tip that is too large and it wont pass through the PTFE tube as it exits the hot end. The comments about the unload process doing a "reverse" ramming seem to be correct since when unloading the Mini seems to first "retract" the filament (I can see some filament reverse out, and then it tries to do the ram and unload, but I think in the first "reverse" ramming of filament causes a bulb to form at the tip of the filament and after that the filament gets stuck and it gets "stripped" at the filament feed gear since the filament can no longer pass through the PTFE tube. This happened every time I try to do a unload AFTER the printer has been idle for some time. This is a pain to try to un-jam because you have to take apart the PTFE tube connections to try to get the filament unstuck. Sometimes I have to take out both sides of the connections to try to unstick the filament.  It unloads properly when I unload immediately after the print finishes.
HOWEVER, I found that if the filament has been left in the printer for a long time then I found that if you FIRST do a "Purge" filament, then immediately after the purge do an "Unload" filament, then it has always unloaded the filament for me without problem and with a nicely formed tip that easily passes through the PTFE tube.

RE: Problems unloading filament? FW 4.0.1

I have found that if I run a print and dont unload the filament immediately after the print finishes I cant just do a unload filament. I will get a filament tip that is too large and it wont pass through the PTFE tube as it exits the hot end. The comments about the unload process doing a "reverse" ramming seem to be correct since when unloading the Mini seems to first "retract" the filament (I can see some filament reverse out, and then it tries to do the ram and unload, but I think in the first "reverse" ramming of filament causes a bulb to form at the tip of the filament and after that the filament gets stuck and it gets "stripped" at the filament feed gear since the filament can no longer pass through the PTFE tube. This happened every time I try to do a unload AFTER the printer has been idle for some time. This is a pain to try to un-jam because you have to take apart the PTFE tube connections to try to get the filament unstuck. Sometimes I have to take out both sides of the connections to try to unstick the filament.  It unloads properly when I unload immediately after the print finishes.
HOWEVER, I found that if the filament has been left in the printer for a long time then I found that if you FIRST do a "Purge" filament, then immediately after the purge do an "Unload" filament, then it has always unloaded the filament for me without problem and with a nicely formed tip that easily passes through the PTFE tube.
I hope Prusa reads this and tries to do some sort of fix for this since its kind of irritating to have to do a purge then unload.
BTW, I don't understand why the Prusa MINI doesn't have an option to just unload the filament right after a print. I assume that they are keeping the filament in the MINI so reprints are easy, or they felt that in a production environment filament changes for every print are not common. But unless they fix this unload filament problem it will remain a real irritation to have to do a PURGE followed by an Unload if your printer has been idle for some time. (I usually run a print and when I go to check on the print it would have been a long time since the print finished, so for me its very common for me to not unload the filament right after I print)

RE: Problems unloading filament? FW 4.0.1

The issue you have may be similar to this on Github: https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/30

Prusa always read issues reported on Github - that is the way to get their attention to a problem 🙂 

RE: Problems unloading filament? FW 4.0.1

Hi area51,

Thanks for the link to the Github issue. I posted my comment to Github, so hopefully a fix will be forthcoming. 👍 

RE: Problems unloading filament? FW 4.0.1

Have any of you attempted downgrading your firmware to see if that fixes anything?

RE: Problems unloading filament? FW 4.0.1

@g-j-sieben

Have not tried downgrading the firmware. Don't know where I read someones comment that they tried downgrading but were unsuccessful. In any case I'll just live with the purge/unload issue until a fix is made. The Mini is printing beautifully so don't want to risk messing things up since I found a workaround for this issue. Downgrading to 4.0 will probably introduce issues that 4.01 fixes. And in any case if I ever have to contact Prusa support directly, if I told them I'm on 4.0 they will probably just tell me to upgrade my firmware and let them know if that fixes the problem. Its always been my feeling that its best to use the most recent "official" release when reporting problems. 😀