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printing issues with original PLA versus Colorfabb XT

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I've received my Ultimaker 2 a month ago, and it has been printing almost non-stop. very satisfied, but now i'm running into some issues.

it is completely original apart from the UltiArjan Rail System i installed to get rid of some underextrusion issues.

i've printed the light saber and some other stuff in Ultimaker blue PLA, which turned out perfect.

I then switched the Ultimaker Red PLA, also went fine.

the one thing i noticed was that if my printer cooled down, the nozzle became clogged and i had to run the Atomic Cold Pull method which got material flowing again.

I then moved to my newest project; the 5 cylinder engine from thingiverse in double size. I printed the moiving parts in PLA red, which all turned out great. I then printed all the non-moving sizes in Colorfabb XT, which was even better. very satisfied with the results.

now when i switch back to PLA, nothing but issues. I have serieus underextrusion, and it seems there are other issues. when i switched back to XT, now also the XT is showing the same issues.

here are some examples;


wall is peeling off with XT

some of the prints;














it looks like quite bad layer adhesion and underextrusion. also the top is very badly printed. i then went back to retrying the print with XT, and now the top and bottom are perfectly smooth





but when i try to print smaller things, like gears, there is all kinds of "rubbish" attached to the gears;







any ideas what is going on here?




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When switching from filament types that have different print temperature make sure to purge the old filament with the new one at the highest temp of both. If you go from XT to PLA purge the head with the temp of the XT otherwise you will keep stuff in.

What temp do you print XT? I print at 235C-245C (depending on speed) and never have problems to switch back and forth.

Also Atomic purge alone doesn't really remove stuff stuck in the hole of the nozzle without needle. Use a small wire or acupuncture needle to really remove stuff and clean the outside of the nozzle with a brush.

A note about feeder: I noticed on mine that the knot on feeder was not deep enough and the filament was only touching the far end of the knot instead of being in the center. It was causing the filament to sometimes slide out of the grip of the know and the bearing when a lot of long retractions were involved.


I also see burned material on your last XT pictures. This show that maybe

A: some material is stuck inside and get out during the print

or B: the head is not clean outside and residues are sticking on your print

or C: your prints are warping upward, stick to the print head during the print and burn (fans too strong or too much ambient air flow).


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thank you for the reply;

to address some points;

i print XT at colorfabb's instructions, 40 mm/s, 250 degrees, fans off. no issues whatsoever.

when i tried switching back to PLA that is when the issues began.

i have just ordered some needles, hope that will help resolve issues. i always clean the head, but i also noticed every now and then a bit of XT will burn unfortunately.

so i tried a new strategy last night, will post below.


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so i was completely fed up yesterday evening and took apart the print head;

the reason behind that was the quality of my prints. i tried printing the stand for my engine, which is a 50 hour print, but after 10 hours in, the printer stopped extruding. i had to print at at least 225 degrees (ultimaker PLA) to get it to extrude and after some underextrusion i had to pump the temp temporarily up to 250 to get a decent flow again. this is the result before it completely gave up;








the pictures above are a mix of the parts i took out of the print head and took pictures of the seperate parts;










to me it seems the teflon spacer is just fine, but the copper print head has nothing but "gunk" in it. i used the method as described in a differnt topic using a burner to completely burn it clean. i cleaned the head, made it all pretty again, i could see through the small nozzle head, completely cleaned it, it all looked perfectly. print head was nice and shiny again. as you can see in the pictures there was a lot of debris in there and i burned all of that out.

put everything back together, started my print of the extruder yesterday, with the default print settings for PLA, so 50mm/s, 0.1 micron layers and 210 degrees with a heated plate of 60 degrees.

these are my results;




suffice to say, i'm not happy with these results..

when everything cooled down, i tried another print, but there was no extrusion, print head clogged again.

i don't know what's happening ... any ideas?


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Try opening the feeder and see that its clean inside. There might be some filament parts stuck in.

If the problem is not in the feeder than you should probably contact support and start by showing this thread. You may have a problem with your heat sensor. Having to boost temp at 250 to get some decent stuff out is not normal.

The support team is good. You may need to repeat some of the content you posted here but in the end they will find the issue. Good luck :)


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so the problem is not in the feeder.. although the stock one isn't much good. i'm printing a new one now that should make it better.

however, i did find a way to make it way better.

after cleaning the printhead yesterday night, and getting so frustrated in the morning, i gave the atomic cleaning method some more thought. i was using PLA to clean.. but what about using ABS?

so i heated the printhead to 260, placed some abs in it till it extruded, the did a quick pull, no cooling down.

came out al black. did that a couple of times until it came out nice and clean and it also extruded clean.

i then did it again, but now let it cool till 150.

came out clean.

put in pla again, factory default settings, so 210 degrees, and did a print.

while not perfectly satisfied, it seems it has resolved quite a bit..

seems i need to patent my own atomic cleaning method where you don't cool off the printhead and you only use ABS...

these are my current prints;




as you can see, most definate an improvement but it seems the top isn't filled out completely.




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ok, will play with the tension a bit, will also order some 618 for cleaning.

got some additional advise (seems i will not be patenting my cleaning method) to heat up the nozzle to 260, then do the atomic cleaning method but instead of cooling down to 90, cool down to 210.

so will try to see if i get it even cleaner after this print :)


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