PLA Filament gone bad?
Hello all.
Over the last couple months I didn't do much printing and the i3 was left gathering a little dust. I found some more projects to print and begun printing, only to find that the print quality seems to have degraded and I was struggling to get quality prints.
Usually I could leave the filament in place from a previous print and then continue on without having to load/unload the filament (I always left it in the extruder after each print because no mention was made about it).
However, now I have to unload the filament and reload it, otherwise the extruder struggles to get the filament out. I thought it was a temperature issue, but the nozzle reaches temperature ok, and once un/reloaded it seems to flow ok - at least initially.
The next problem is that the prints have a sort of mottled appearance, almost as if there's not enough plastic coming through.
I thought maybe the nozzle was blocked and since I was unable to perform the "yank" technique I bought some spares from Prusa. However the new nozzles didn't change anything.
I thought it might be a software issue since I had started using Simplify 3D, but then I got the same results from Slic3r as well.
I'm still using the Prusa roll of filament that came part of the kit and I recently read that humidity and environmental factors can affect filament - although in all honesty I thought "It's plastic, isn't it supposed to be waterproof?"
That being said, I wondered if me leaving the filament outside on the i3 for many months is the reason for the degraded printing. I was wondering if more experienced eyes would recognise the signs of degraded filament from the image here:
Since I still have a decent amount of Prusa filament I didn't want to buy some more yet until I had used up the old roll (being environmentally aware) and would politely ask the community if they could confirm my suspicions about the filament *OR* if they recognise the print quality as a result of a different issue that I've not yet discovered 🙂
Thank you for your time.
*edit* Forgot to say that I'm working with PLA filament. Doh!
Re: Filament gone bad?
Hi Robert
Depending on storage conditions, filament can degrade rapidly. It soaks up moisture from the air, and when heated, the moisture in the filament boils and steam is ejected instead of filament, and the result is what you see.
However, it may not be the filament, and a nozzle clean is worth trying. follow the relevant instructions from this page: https://ultimaker.com/en/manuals/149-atomic-method
When you pull the filament out, if the end is black or irregular, dismantle the extruder and check the PTFE tubing for any distortion or burning.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: PLA Filament gone bad?
Hi, Peter.
Thank you for replying.
I did try that method. I couldn't recall exactly the name of it so I referred to it as the "yank" method, in that you had to yank hard on the filament to pull it out of the nozzle.
The issue I had is that once it reached 90'c it just refused to come out and the force of pulling it out was causing the X axis rods to bend, so I gave up. That was the point when I decided to buy new nozzles - it seemed a safer choice rather than warping the rods.
Although it may not be much use, I have uploaded an image of the filament when it's unloaded from the extruder.
I will get some more filament since the original reel of PLA has been on the i3 since I bought it back in October last year, and with there being a Winter it's very likely that it would have degraded as time has progressed.
Until yesterday I was completely unaware that PLA can be affected this way. Perhaps this information should be made more wide-spread and included in the manual, advising users to seal it away when not in use for precisely these reasons? It could save a lot of unnecessary wastage of PLA and also wasted tech time with Prusa trying to sort out problematic prints.
Thank you again for your help.
Kind reagrds,
Robert
Re: PLA Filament gone bad?
Hi Robert
The filament photo doesn't look great; the nozzle form is missing from the end, but there are no black specks on it, so hopefully, the PTFE tube is OK - but you may end up replacing that if a new nozzle/filament still causes issues.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: PLA Filament gone bad?
Speaking from experience, that is the PTFE tube needing to be replaced. This is what happened to mine and was unable to "yank" clean the nozzle as well. Replaced the PTFE tube and all was good again.
Re: PLA Filament gone bad?
Richard
I agree that may well be the case, but Robert has hardly used the printer and I don't want to tell him to take the extruder apart until he has tried all other options.
Dismantling the extruder has proven difficult for some, resulting in replacement thermistors or other damage.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: PLA Filament gone bad?
This PTFE tubing...
does it go from just below the filament drive wheel all the way to the back of the nozzle>
is it 4mm OD, 2mm ID ?
what stops it coming out when the filament is withdrawn?
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
Re: PLA Filament gone bad?
Hi Joan
There is a cutaway image of the hot end showing the PTFE tubing here: http://e3d-online.com/Lite6 (scroll down a tad...)
At the top of the hot end, there is a black plastic ring in a brass (I think) insert. When the black plastic ring is lifted, it locks the PTFE tube.
You are correct regarding the tube dimensions.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: PLA Filament gone bad?
Several months? I get nervous if my filament is left out for more than a few days. Not sure why Peter wants you to do a nozzle cleaning, because in my opinion that is most likely a "water-logged" filament you have. Not sure if there is a remedy, for it though.
/Sascha
Re: PLA Filament gone bad?
Sascha
I think Robert is probably sorted; his last response was a couple of weeks ago.
If you would like me to explain why I suggested a nozzle clean, I will but the clues are there.
Sounds as though you keep your filament under water 😉 I have gone past the stage of worrying about damp filament and no longer bother to store it in a dry environment. For me, it tends to be the cheaper Chinese filament which degrades quickly and I no longer buy that.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: PLA Filament gone bad?
Ah, I didn't notice the thread age, sorry!
I have to agree about filament quality there. I bought a couple of eSun filaments, and besides them almost stinking during print (compared to the sweet candy-like scent of the Prusa PLA), both the surface finish and print quality is slightly worse. Nevermore 🙂
/Sascha
Re: PLA Filament gone bad?
My apologies for not re-visiting sooner. Finances prevented me from immediately getting a new reel of decent PLA and then life threw some other things at me to delay me further.
An update then:
After purchasing some new PLA and keeping it sealed away until it was needed I have found the quality of prints has profoundly improved. The layers appear to be good and I'm not seeing any weak layers from previous attempts.
As of yet I haven't replaced the PTFE tube. I'm seeing how it works without going that far, although I did get an extra one (kindly supplied by Prusa when I ordered some replacement nozzles).
My only remaining problem I have noticed is if I'm printing a large object the filament feeder appears to be trying to push filament through the nozzle at a faster rate than it can allow. This results in some "thunk thunk thunk" noise from the extruder, which I believe is the gear wheel skipping as the filament can't be pushed in any further.
I noticed this effect when I saw some sparsely printed layers and wondered why and then I reasoned that the software probably generated the gcode with an assumption of a certain flow rate and that the flow rate was higher than was capable of being squeezed through the print nozzle. I dialled back the speed to 65% and the "thunk" noise receded and the layers printed properly again.
Thank you all for your very valuable input and insights.
Re: PLA Filament gone bad?
Hi Robert
Great news, thanks for letting us know
It does sound as though you may still have a restriction in the extruder which will probably be resolved with a change of the PTFE tube and/or nozzle.
Changing this is not difficult, but rather time-consuming and needs to be done carefully.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: PLA Filament gone bad?
Both you and Richard have said that the PFTE tube could need replacing so I think I'll do that. I'll read up on it and see if I can get it done this week.
Thank you for the advice.
Kind regards,
Robert
edit:
Just changed the PTFE tube thanks to the guide here: http://manual.prusa3d.com/Guide/How+to+replace+PTFE+tube/82#_ga=1.193232490.655764189.1446353170 . The diameter was noticeably reduced which explains the struggle to keep the filament flowing. It didn't take too long to undo, but that's largely thanks to a motorised screwdriver. When I first did this with the allen key it took ages because it was so fiddly and with my hands I kept dropping it too.
Here's a picture of the new tube and original one for comparison:
