Bad filament or bad settings?

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Bad filament or bad settings?

Post by dryeti » Sat Jul 26, 2014 6:25 pm

Hi all,

I have my M2 for some months and in general I'm quite happy with it. After running out of MakerGear filament I ordered a couple of rolls of PLA in different colors (the brand is NuNus). I would buy makergear filament but as I'm based in Europe shipping is quite expensive (in terms of money, time, environment,...). With this new filament I get quite bad results (see pictures).
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I'm wondering whether I just haven't found the right settings for the new plastic (I tried a lot) or whether its quality is just bad. Compared to MakerGear PLA it seems to be more viscous.
I'd appreciate your thoughts!

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Re: Bad filament or bad settings?

Post by dryeti » Sat Jul 26, 2014 6:35 pm

I forgot to mention that the problem varies from roll to roll. Using the same setting, e.g., the roll of transparent PLA performs much better than the gray one that you can see in the pictures.

Dale Reed
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Re: Bad filament or bad settings?

Post by Dale Reed » Sat Jul 26, 2014 6:49 pm

I believe the pigmented filaments (MG included) have slightly different temperature requirements from the "natural" filaments. On the pigmented ones, try running the extruder 5 degress or so hotter and see if that helps. Don't be afraid to run pigmented PLA even 10 degress hotter to get the same kind of adhesion and flow. If your run the bracelet and it has a very "matte" finish and it's easy to split it apart between layers, you probably need to bring the hot end temperature up a tad.

The pigment might also affect adhesion to the bed. Are you running it onto the bare glass? If so, bring the bed temp up a few degrees as well, or try a light misting of hairspray ("extremely monstrous super mondo ridiculous hold" varieties with lots of polymers in them work best) and see if that helps the filament stay down.

Having the filament sticking up into the nozzle path is a recipe for triggering a nozzle clog, or for knocking the extruder motor/extruder/hot end assembly out of line or loose (resulting in offsets in prints) or cracking the motor mount.

Hope this helps!

p.s.: Anybody have a reference for the conversion from tads to degrees Celsius?

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Re: Bad filament or bad settings?

Post by dryeti » Sat Jul 26, 2014 8:05 pm

Hi Dale,
thanks for your answer! I just tried another print at higher temperature but the problem remains (see picture).
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I also experimented a lot with different temperatures to solve the issue before, but it never really helped.
I also think that first layer adhesion is not the core of the problem. My guess was either overextrusion or underextrusion: it is weird, sometimes there seems to be too much filament - especially for the first layer - such that it piles up to chunks. Then, the nozzle runs into these chunks and spreads them around. On the other hand, sometimes the lines seem too thin or even missing.

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Re: Bad filament or bad settings?

Post by jimc » Sat Jul 26, 2014 8:14 pm

ive gotten real poor quality abs filament before. it just wasnt made from a grade of abs that adequate for 3d printing. it looked just like your failed prints. i took my hot end apart, cleaned it out and switched to another brand and it printed just fine.

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Re: Bad filament or bad settings?

Post by jsc » Sat Jul 26, 2014 9:39 pm

Having variant first layer quality is often a sign of an unlevel bed. With a clear, clean glass bed, try bringing up the bed manually almost touching the nozzle, and look at it from the side. Watch the nozzle and its reflection as you move the bed and extruder back and forth, and see if the visible gap grows larger on one side or the other.

If that is not the problem, then you can manually adjust the extrusion multiplier in the machine control panel while the first layer is being laid down. Try bringing it down to an unreasonably low amount, say, 70%, and then adjust it up until it stops being too thin.

Also, filament varies widely in quality. WIDELY. You may end up just chalking it up to experience.

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Re: Bad filament or bad settings?

Post by dryeti » Sun Jul 27, 2014 5:14 pm

After checking the bed leveling which seems ok, I followed jsc's advise for adjusting the extrusion multiplier.
I started at 70% as suggested which turned out not to be too unreasonable after all. Strangely, at 70% the print was much better -so I let it finish at this value.
The first layer still suffers from the incorporation of some of the chunks described above as you can see here:
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Nevertheless, the rest seems ok:
CAM00016sm.jpg (88.31 KiB) Viewed 4793 times
Now I'm wondering whether my settings are messed up or whether something is wrong with my nozzle (as 70% seems to be a big deviation from the standard value).
In case anyone finds time for a sanity check - that would be great - here is my fff file:
fff file - unlike in the file the extrusion multiplier was 70 for the print
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Re: Bad filament or bad settings?

Post by jsc » Sun Jul 27, 2014 5:24 pm

If 70% works for the first layer, perhaps your first layer z height is too low?

Try a print at a more usual extrusion multiplier (90-95%), but for the first layer, try clicking the Z screw knob counter clockwise one click when the skirt is going down. That will increase the layer height. If the first layer goes down okay, let it print for two or three additional layers to make sure you're not getting issues. If it looks good, then adjust your Z height screw appropriately.

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Re: Bad filament or bad settings?

Post by jsc » Sun Jul 27, 2014 5:30 pm

Looking at your FFF, some (possibly unrelated) things:

It is in the old format. That may be because it was originally generated on an old version, but if you have not, you should probably upgrade to 2.1.1.

Your extrusion width is set to manual at 0.35. I recommend you set it to a manual width of 0.40; it can be up to 0.50, but I like 0.40 because it is easy to design around.

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Re: Bad filament or bad settings?

Post by willnewton » Fri Aug 01, 2014 9:21 pm

Simple and obvious question, but I did not see it mentioned. Are you running with the bed heat on and at the proper temp?

Also, does your first layer look better with a layer of painters tape, or glue stick, or hair spray, etc. applied to the bed? I rarely print on a bed that does not have a thin coat of glue stick applied anymore. It eliminates so many headaches. If you try the painter's tape and it prints better, then it is an adhesion problem, not extrusion problem.

These look like adhesion issues mixed with a bit of layer width issues as jsc suggested. I would use his recommendation on manual layer width of .40mm. This is mostly to keep your PLA touching itself, which helps with adhesion.

You have not mentioned your first layer height percentage setting either. This is a very important setting for tweaking that first layer. You should be laying a ribbon, not a string. I would reset my extrusion multiplier to 90-100% as stock. Although it may be a part of the problem, there are many other places to check before you start fiddling with it. Layer height percentage does affect the extrusion setting in a way similar to the multiplier settings, but only for the first layer. My feeling is that you have a first layer issue, not a global extrusion issue.

The order of checking things out I use:
Bed leveled? Judging from your print size, which takes up a fair bit of bed, your leveling step is critical.
Z-height set? Done AFTER bed leveling
Proper temps for bed/extruder?
Bed glass prepped with glue, tape, or super cleaned with acetone or denatured alcohol between prints?
First layer height settings?
Laying a ribbon?

Do you have a favorite small print and a bit of the Makergear PLA to try a print using the stock settings? Some issues will be easier to diagnose whether the problem lies in the setup, settings, machine, or filament when you print an old favorite. If I have an issue that doesn't resolve, I print a 1" cube in MG PLA black with the stock settings. I know exactly what this is supposed to look and print like, making it very easy to troubleshoot issues.

You also mentioned the new PLA was more viscous, so may need more heat, but just as a shot in the dark, I would double check that they sent you PLA and not something else. Perhaps they have different formulations and different settings, so check that you are using their recommended settings vs. the MG PLA settings.
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