Please help - PLA Filament stuck in brand new AA0.4 Print Core

[sproutdesign 5]

Hi,

 

I have just replaced my S5 print core, as PLA became stuck in my old one, and the same has happened on first use with a brand new print core.

 

With the brand new AA0.4 Print core, I successfully loaded white ColorFabb PLA which extruded ok, and had printed XY calibration OK.

 

Set it to do a weekend long print on Friday and left it while it the first support layer of PVA was printing from the other BB core.

 

Today it looks like the PLA was stuck even before it started printing and I cannot remove it.

 

Looking at the printer closely in the photos, a wide flange has formed in the filament around the top of the tube going into the print core, which also means the filament can't be pulled up through the head.

 

This also means I cannot remove the new print core or filament. It is absolutely stuck.

 

The front fan is spinning OK and inside the head is clean and free of obstructions or fibres.

 

This must be what had happened to the old print core with a different PLA, as when I tried a hot pull, the filament cracked rather than pulling out, breaking at this point and is impossible to remove.

 

I'm not keen for the same result with this brand new print core and would like to stop this happening.

 

Please can you suggest how to get the filament and new print core out, and what to try to fix the recurring issue?

 

Thanks in advance

Edited April 12, 2021 by sproutdesign

[Carbon 28]

Can you heat the print core? If you can this will help you remove the core.

 

Is the ColorFabb PLA you're using Ø 2.85mm?

 

 

[sproutdesign 5]

Hi,

 

Yes its 2.85mm 'Standard White', and the same happened with the old print core using 2.85 orange

 

The printer is otherwise working normally and I can heat the print core, but it is not possible to pull the print core out with filament that has formed a flange like this as it cannot move up or down and the gap between the print core and head is too small to bend the filament to pull the print core out.

 

I'd also really like to work out how this is happening in the first place. Recently updated the printer to 6.3.0

Edited April 12, 2021 by sproutdesign

[guna 0]

Hi,

 

same issue is happening with me, but i can able to print with ABS. Recently i got to know that my front fan of printhead is also not working properly.

[sproutdesign 5]

Yes I can see how the front fan not working could cause this.

 

But the front fan on my S5 is working OK.

 

I've been offered a back-to-base repair by the reseller, or a new head, but would really like to be able to fix it myself as the print core is brand new. 

[Torgeir 242]

Hi @sproutdesign,

 

You mentioned that the filament cracked when trying to pull it out, -so maybe your filament have attracted to "much" water from the air (some high humidity air)? In such case -PLA will/can be brittle. Also this can force melted filament to go upward into the "cold part" of the extruder. The filament might be kind of glued stuck and may lead to grinding the filament at the feeder wheel.

 

This happen when water affected filament arrive the heat block and the pressure inside the heat block violently rice..

When the nozzle is at the first layers, little happen at the nozzle, but on the top the melted plastic and water vapor will try to escape this way.

 

You might remove the bowden tube and the locking clip -then use a thin pointed pliers to remove the remaining filament.

Remember to heath up the block before try to removing the filament..

 

Have a look at this tread:

 

 

Thanks

Torgeir

[Torgeir 242]

5 hours ago, guna said:

Hi,

 

same issue is happening with me, but i can able to print with ABS. Recently i got to know that my front fan of printhead is also not working properly.

 

Hi @guna,

 

If the front fan is not working properly, heat will climb upward and heat up the upper "cold" side of the extruder.

This lead to that the filament start softening here and will soon be stuck. The feeder wheel will then grind into the filament and soon spinning free.

 

The forward cooling fan is there just to prevent this to happen and keeping the upper part "cold".

The fan may be blocked by collected "stringing" material into the fan blades. But can also occur due to an open wire in the two feeding wires for this fan, but if this happen the fan would normally not rotate at all.

 

Thanks

Torgeir

 

Edited April 12, 2021 by Torgeir
Text error

[JohnInOttawa 104]

Hmmm.  That seems annoying.  If it also happened with the old print core and another filament type, I would go out on a limb and say the issue is external to both the print core and the filament.  Back to that cooling fan.   There are degraded modes that do not involve the fan being completely stopped.  If it were me I'd be looking at that fan with magnification to see if anything is interfering with airflow or rotation.  I recently pulled nearly 30 cm of wound, hair fine filament from around my cooling fan. 

 

There are two ways I might go about removing this print core.  One at a time.

 

It's hard for me to get a true sense of the gap from your photo. Do you have room to get a very thin (credit card thickness or less) strip of metal in between the top of the print core and the structure of the print head?  If so, you might want to consider  heating up that thin strip and using it as a knife to melt/cut the PLA.   There is some risk of melting anything else you touch with your hot knife though.  You could employ a similar strategy with thin wire - again, unsure how much lateral room you have to work with getting the wire looped around the PLA might not work.

 

If you do succeed in severing the PLA, once the print core is out you can manually push the PLA down through the (now empty) print core opening and cut off any offending wide point.  That would still leave you with a blocked print core but I think you would be OK to navigate from that point.

 

John

 

 

[sproutdesign 5]

Thanks for all the suggestions.

 

After a lot of wiggling and pulling, I was able to pull the bowden tube up from the head - pulling the ground end from the feeder into the bowden tube.

 

That gave me a bit of slack and I was able to expose more of the filament by undoing the 4 long bolts on the head to increase the gap between the core and inside top of the print head.

 

That gave just enough space to bend the filament and pull the core out - the filament was actually not stuck in the core, just the melted collar it had made couldn't go up or down.

 

It could have been caused by moisture in the filament creating a backflow, and perhaps the filament was too far into the head while the first PVA layer was printing.

 

I set it up again after hot/cold pulls with the same filament having cut a couple of meters off it, and it printed without any problems.

[JohnInOttawa 104]

Great news!  Thanks for the update.