Filament Drive wheel skipping - intermittent  

Re: Filament Drive wheel skipping - intermittent

I have the exact same issue...
Followed the same steps. Do not what is it

Re: Filament Drive wheel skipping - intermittent

Could it be that there are some leftovers of the taulamn filament in the pathway of the filament?
I had the same problems when switching from ABS to PLA. Because the ABS needs 255 degrees and PLA " only" 215, the were some remains in the pathway and that blocked sometimes the extrusison of the PLA. My solution was to load PLA filament via the menu, with the extruder temperatuur via the menu set to 255. I could see by the color of the PLA that was extruded that there were some leftovers of the ABS.

Let me here your results

Frans

Re: Filament Drive wheel skipping - intermittent

Hey Frans,
Using a higher temperature didn't help me..

what about you byron?

Re: Filament Drive wheel skipping - intermittent

So according to your giving info, the problem is not "before" the filament entering the PTFE tube, correct?
Did you replace the nozzle correct? Is it making contact with the heatbreak?

A simple test:
Did you try manually feeding (by hand) the filament? Unscrew the idler (2 screws with springs and washers). Then you are able to push trough the filament with heated extruder. There should be a little bit resistance when pushing the filament, but it should go smoothly with some permanent resistance as the filament melts and is pushed out the nozzle. This is a simple test for checking the pathway of the filament.

If you image the path of the filament (entering the PTFE tube in the heatsink, entering the heatbreak, entering the nozzle) there should be the obstruction.
Is the PTFE tube damaged? To check this you have to remove the extruder cover, take the extruder from the extruder body and remove the PTFE tube (don't forget to push down the ring of the entrance of the heatsink) and check the ptfe tube.

If ptfe oke the obstruction is further down and you have to disassemble the extruder to check (nasty job, but done with care no problem, special attention with the wires!!)

Let me here your progress

Frans

Re: Filament Drive wheel skipping - intermittent

Hey Frans
thank you for your help.

I tried with no success to push the filament manualy, it just stayed stuck in place.

I'm adding a photo of the tip of the filament, where it broke, in the extruder lager (silver filament) .

now i'm trying to disassemble the extruder nozzle, to check the pathway and the PTFE tube. I find it hard to unscrew the nozzle: the heating element is hard to grip, but I'll keep trying. adding a photo of the extruder uncovered.

Re: Filament Drive wheel skipping - intermittent

I know by my own experience how carefully you must handle. The wires are fragile!!!

You can take the extruder off by taking off the cover (and the fan) and then try to take off the PTFE tube (hold done the dark ring above the heatsink). You need 3 hands (my wife is always willing to help 😀 ). I use a little needle nose pliere to take off the PTFE tube. Check the tube.

If tube oke then comes the next step: take off the heatsink

There are 3 ways:
1. remove the extruder completely and disassemble (post how to are in the forum, I think from PJR in the MMU part) the thing.

2. remove the extruder by loosening the heat element and the thermistor from the heatblock and disassemble the thing.

3. remove the heatsink while the extruder is only loose by taken off the cover off the extruder carriage and gently take the extruder loose
I used a bahco (not a big one) for holding the heatblock and therefore holding the extruder in place so not to damage the wires . The bahco helps to hold the extruder to keep "inplace", working with so few space/working place. Place a peace of thick paper around the heatsink to avoid damage and with the thick paper around it, use a pipe wrench to turn off the heatsink. Do it gently. When unscrewed you can check the pathway.

At the end: place the extruder back and check, recheck that the wires oke, especially the two wires off the thermistor. They should be separated and they are thin and so very fragile. I use an spotlight to see if its oke.

Hope this helps, but please work very concentrated, try to think one step ahead, because the extruder is so fragile (not the aluminum, but the wires).

Check the images on internet how the composition of an extruder looks like. It will help you to visualize the handling

Succes, let me now your progress

Frans

Re: Filament Drive wheel skipping - intermittent

Could it be that there are some leftovers of the taulamn filament in the pathway of the filament?
I had the same problems when switching from ABS to PLA. Because the ABS needs 255 degrees and PLA " only" 215, the were some remains in the pathway and that blocked sometimes the extrusison of the PLA. My solution was to load PLA filament via the menu, with the extruder temperatuur via the menu set to 255. I could see by the color of the PLA that was extruded that there were some leftovers of the ABS.

Let me here your results

Frans

Hi Frans, I ran some filament purge through to insure no residue. Also tried some basic extrusion at 290 to try and burn out the excess. This did not help. 🙁

Re: Filament Drive wheel skipping - intermittent

Could it be that there are some leftovers of the taulamn filament in the pathway of the filament?
I had the same problems when switching from ABS to PLA. Because the ABS needs 255 degrees and PLA " only" 215, the were some remains in the pathway and that blocked sometimes the extrusison of the PLA. My solution was to load PLA filament via the menu, with the extruder temperatuur via the menu set to 255. I could see by the color of the PLA that was extruded that there were some leftovers of the ABS.

Let me here your results

Frans

Hi Frans, I ran some filament purge through to insure no residue. Also tried some basic extrusion at 290 to try and burn out the excess. This did not help. 🙁

Re: Filament Drive wheel skipping - intermittent

Could it be that there are some leftovers of the taulamn filament in the pathway of the filament?
I had the same problems when switching from ABS to PLA. Because the ABS needs 255 degrees and PLA " only" 215, the were some remains in the pathway and that blocked sometimes the extrusison of the PLA. My solution was to load PLA filament via the menu, with the extruder temperatuur via the menu set to 255. I could see by the color of the PLA that was extruded that there were some leftovers of the ABS.

Let me here your results

Frans

Hi Frans, I ran some filament purge through to insure no residue. Also tried some basic extrusion at 290 to try and burn out the excess. This did not help. 🙁

Re: Filament Drive wheel skipping - intermittent

I know by my own experience how carefully you must handle. The wires are fragile!!!

You can take the extruder off by taking off the cover (and the fan) and then try to take off the PTFE tube (hold done the dark ring above the heatsink). You need 3 hands (my wife is always willing to help 😀 ). I use a little needle nose pliere to take off the PTFE tube. Check the tube.

If tube oke then comes the next step: take off the heatsink

There are 3 ways:
1. remove the extruder completely and disassemble (post how to are in the forum, I think from PJR in the MMU part) the thing.

2. remove the extruder by loosening the heat element and the thermistor from the heatblock and disassemble the thing.

3. remove the heatsink while the extruder is only loose by taken off the cover off the extruder carriage and gently take the extruder loose
I used a bahco (not a big one) for holding the heatblock and therefore holding the extruder in place so not to damage the wires . The bahco helps to hold the extruder to keep "inplace", working with so few space/working place. Place a peace of thick paper around the heatsink to avoid damage and with the thick paper around it, use a pipe wrench to turn off the heatsink. Do it gently. When unscrewed you can check the pathway.

At the end: place the extruder back and check, recheck that the wires oke, especially the two wires off the thermistor. They should be separated and they are thin and so very fragile. I use an spotlight to see if its oke.

Hope this helps, but please work very concentrated, try to think one step ahead, because the extruder is so fragile (not the aluminum, but the wires).

Check the images on internet how the composition of an extruder looks like. It will help you to visualize the handling

Succes, let me now your progress

Frans

Thank you for all your comments Frans. Very detailed, and appreciated.

I would hope that after such small amounts of printing (less than 1kg) we would not have this kind of issue. But perhaps that is the case.

I will have to inspect this and the ptfe tube later.
I was having some success printing at 235 degrees after watching many layers and manually pushing the filament in by hand whenever a click was heard.

Thought that maybe the 235 temp was the ticket and got bold and ran an overnight print....disaster. we have filament extruded everywhere. somehow it came back against the nozzle and a humongous blob of melted PLA is all over the extruded and bonded to it. Spending today and tomorrow with a heat gun carefully chipping away to remove the buildup. Hope we do not have serious damage but it was a big error to run without supervision when a known trouble was not completely cured.

Re: Filament Drive wheel skipping - intermittent

Hey Frnas and Byron.

Not very good news from my side either:
I managed to open the clogged nozzle and to continue printing.
I did it by feeding the filament manually with great amount of force, ( which I already tried like a bazillion times before, but some how, when the extruder covers were off, I managed to do this).

the bad news: I ran test and calibration, everything is fine.

I started a new print, after not many layers, the same thing happend once again!!!
the extruder skipped lines, the print is to the garbage, and now i'm facing something( like yeasterday and the day before), which looks like a clogged nozzle, but its obviously not the real problem...

Re: Filament Drive wheel skipping - intermittent

Please check this to. I suggest that you only print while attendend 😯
shop.prusa3d.com/forum/prusa-i3-kit-building-calibrating-first-print-main-f6/-before-you-ask-troubleshooting-video-updated--t472.html#p39190

Re: Filament Drive wheel skipping - intermittent

Hello, I had the same problem. I built the MK2S on Christmas. I only did one calibration print and startet immediately a 11 hour print. After 3 days of perfekt printing over night I startet a print with supports, but I forgot to switch on support in cura. On the next morning I had a big lump around the head including the cables. I tried to clean all with a heatgun. I thought I damaged the thin cables from the thermistor, but after I separated them carefully I could print again. But since that problem all prints get stucked after some time of printing. The transport wheel is clicking.
At this moment I think the temperature of the head is ok, I thought one problem could be the regulation of the temp. But I don't think so. I am not really sure that the problem is caused by my fault to print a model with overhanging parts without supports. But after this I could only print little models.

I will try today to replace all parts of the head except the heatsink body. I ordered the heater cartridge, the thermistor, the heater block, the nozzle and the printed parts of the X axis. So 90% of the head is new after replace them. I hope it helps.

Regards,
Gerd

Re: Filament Drive wheel skipping - intermittent

Could this be a worn hobbed pully? Perhaps the other filament wore the furlings down on it and now it just slips because the other filament is softer and there is a gap?

Re: Filament Drive wheel skipping - intermittent

Unlikely (but indeed it can) if you cannot push through the filament by hand with a heated extruder. If that is not possible there must be an obstruction in the pathway of the filament.

Keep me informed 😀
Frans

Re: Filament Drive wheel skipping - intermittent

Apologies if this has been mentioned but try a cold pull. It works wonders, in fact I often do it on changing filament anyway as it give a nice clean change.

1)Take some (preferably white) filament and load it into the hotend.
2) Undo the tensioners
3) manually just squeeze a little more through (by pushing)
4) let the hotend cool down, any rubbish remaining in the nozzle or hot end will get stuck in the pla.
5) heat the hotend to around 80-90 (enough to soften the pla but not melt it.
6) physically pull it out, if done properly you will get a filament pulled out that looks like ====------===} the thin bit is stretched out filament the knob on the end is the nozzles inside profile. You should see any debris against the white quite easily.
7) repeat until it pulls clean.

If it pulls clean straight away then its not your issue but its a useful technique anyway, if the filament wont pull out increase the temp, if the thin bit is really long or breaks decrease the temp.

For more on the method google Atomic Pull or Cold Pull.

You may be surprised at how much charred debris is in there. Manual cleaning is a nightmare and you risk breaking the heatbreak.

Re: Filament Drive wheel skipping - intermittent

Hi,
I just started having the same issue tonight and it has been happening ever since.
I've been printing for a year now, never used anything other than PLA. Now, all of a sudden, a few layers into the print, the feeder wheel starts skipping and doesn't feed filament into the extruder any more. From the misprint tonight, it looks like it caught on a few times, there's a layer missing, then one complete one and so on, until it failed completely 3-4 of these weird cycles in.
When I unload the filament and load it again, everything works like a charm until it fails halfway into the next print again after 3 hours of flawless printing. This keeps happening to me the whole day today.
I tried changing filaments, tried tensioning the tension screws holding the idler, I tried multiple cold pulls and even higher print temperatures, but nothing seems to help.

cheers,
Ivan