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PTFE tube clogs with PLA  

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Craig
(@craig-6)
New Member
PTFE tube clogs with PLA

My MK3S worked well for months, but recently has been suffering from PLA melting in the PFTE tube and hardening there, messing up prints and not allowing my filament to unload.   I’ve taken the head apart several times and replaced the tube, and that corrects it for a little while, then the problem recurs.  

Can anyone help me fix this issue once and for all?

 

 

Posted : 02/05/2020 11:54 pm
JoanTabb
(@joantabb)
Moderator
RE: PTFE tube clogs with PLA

Could be many causes... 

In my case if I print with 0.8mm retraction I frequently get jams (At the BOTTOM of the PTFE) when I use 0.4mm retraction (with my Mk3's) I don't get jams. 

With my Mk2 MMUv2 (Bowden feed printer), the default is 4mm retraction, I use 2mm, again this seems to stop clogging. 

If I do get a clog, the first thing I try, is heating the nozzle to a high temperature and try pushing the filament through with the nozzle in mid air. this usually clears the clog... 
If the filament breaks off, I use a 1.5mm allen key, to push the filament through... 

Some people get clogs above the PTFE, this can be caused by high ambient temperatures. or having the printer inside an enclosure

some people get clogs due to contamination in, or on the filament, so far I have not had this problem...  (I have never used the Accupuncture needles... (I always lose them) )

Other people's experiences may vary!

(I have had self inflicted clogs, by trying to print PETG at PLA temperatures... that doesn't go too well...)
and I had adhesion problems a couple of nights ago...  I mistakenly put white PLA on the printer with a PETG print job...   the heatbed was simply too hot! I thought I was printing PETG... 
In my early days, a friend sliced a copy of the gear spinner, she used an ABS profile, and used PLA filament... Surprisingly  the bottom layer was rubbish, all warped buy the excess temperature,  the rest of the print was a bit messy, quite stringy, but when finished,  the gears still turned
round... 
Your best bet is to identify where the clogs are happening then we may be able to shed some light on the subject

Have you read the Prusa Knowledge base information https://help.prusa3d.com/en/article/clogged-hotend_2008

Regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 03/05/2020 12:20 am
Craig liked
Craig
(@craig-6)
New Member
Topic starter answered:
RE: PTFE tube clogs with PLA

@joantabb

Thanks so much for the advice...   Those are all excellent suggestions.  I'm not sure how to adjust the retraction level, so I better do a little research!

I did have a major ENDBLOB incident earlier where, upon removal, the thermistor in the hotend was damaged so I replaced it.   In hindsight, I never had this problem before this incident.   I used a thermocouple and DVM to measure my hotend and it always seems to be about 10 degrees cooler that the PRUSA control panel thinks it is.   ( If I set it for 200, the DVM reads about 190 )   I have no idea if this is a contributing factor, but I thought I would throw it in the clues-pile.  

I did a temperature calibration ( which passed ) and did another printjob afterwards, which clogged and failed shortly after.

Any feedback would be appreciated!   Thanks so much for your time

 

Craig

 

Posted : 04/05/2020 3:12 am
TT
 TT
(@tt)
Active Member
RE: PTFE tube clogs with PLA
Posted by: @joantabb

Some people get clogs above the PTFE, this can be caused by high ambient temperatures. or having the printer inside an enclosure

I'm also experiencing frequent clogs since I upgraded my MK3 to an MK3s, and I have my printer in an enclosure.  Is the consensus that when printing PLA I shouldn't be using an enclosure?

Posted : 18/07/2020 6:05 pm
JoanTabb
(@joantabb)
Moderator
RE: PTFE tube clogs with PLA

If the enclosure is raising the printer ambient temperature it will almost certainly cause problems.

other companies with BOX printers, like Raise3D,  also suffer from higher ambient temperatures Raise, for instance recommend that the top of the case, be left open when printing PLA! See Video ( )

I suspect if you leave the door open on your enclosure, you will be Ok! 

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 18/07/2020 6:33 pm
Peter M
(@peter-m)
Noble Member
RE: PTFE tube clogs with PLA

On https://www.thingiverse.com/   you can find a stl for a extra fan on the extruder, this cools it down very good, so no heat goes through the gears to the filament.

And ad a extra fan to your case, leave door open, and blow air in the case, you could try this first and then ad a extra fan on extruder.

To test you could try with a table fan and blow in the enclosure.(or top of enclosure).

And of couse clean your extruder, where the cooling takes place, there builds up a lot of dust.

 

You also could print with petg.

This post was modified 2 years ago by Peter M
Posted : 19/07/2020 5:15 am
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