Identifying PLA/PETG or ABS

  • I received a roll of Black filament as a present, and struggled to print with it, experiencing extreme under-extrusion (and slippage of the hobbed gear). Higher temperatures seemed to work better, particularly in freeing up the extrude rate.

    The filament is advertised as PLA, but without any temperature recommendations that I can find on the vendor's website (or the amazon listing). Amazon reviews have a fairly wide range of temperatures, but the listing aggregates several colours. There is a suggestion that the filament may be PETG, or ABS.

    I have tried using acetone, and it dissolves roughly the same as some ABS I have, my PLA shows some weakening but doesn't dissolve.

    Below about 215°C, extrusion is borderline non-existent. I printed at 225°C with a fan, and it extruded kind of OK, but adhesion was poor. 240° without a fan seems a bit on the hot side (see photo). Even 255°C seems to extrude OK without burning. There is no smell I can observe (but I have a cold). It burns with a small blue flame, and minimal smell (kind of like natural gas).

    One factor against it being ABS is that with the bed at 60°C, printing both a benchy and the heat tower below, there was no warping. Bed adhesion remained good.

    Is there anything I can do to better identify this filament and decide the best combination of fan/temperature without wasting too much time?

    255° to 225° heat tower, seems different to the ABS i've used:
    enter image description here

  • StarWind0

    StarWind0 Correct answer

    6 years ago

    There is a trick. However I would like to mention that chances are that the random spool you pickup from most stores, especially no name brands, are either completely lying to you about its material or is mixed / cut with cheaper fillers. All about finding a good brand. Course rarely does one actually need pure PLA, a mixed material will often perform as well without you even noticing. Aside from the temp difference. Not to say it is right.

    Now the trick is this. While I don't advise ever breathing in potentially carcinogenic plastic smoke. You take a lighter. Burn it. If it smells sweet it is PLA.

    From this link from digital trends about PLA VS ABS you can see why it has this smell.

    The thermoplastic is also more pleasant on the nose, as the sugar-based material smells slightly sweet when heated opposed to the harsh smell often associated with ABS. However, while PLA might seem like a better overall choice at first glance, it features a far lower melting point than ABS.

    Also not responsible if you burn yourself or your property. At your own risk.

    Just warming it with lighter might work too. But just burning a small section. It will be real clear.

    Or you could just drop a bit into aceton and see if it melts. PLA will mostly just look like crud after being treated is aceton. ABS is 100% dissolve.

    We see from these forums that PETG does not dissolve via Aceton. So you can test you material. If it does disolve it is ABS. If it smells sweet when burned it is PLA. If it melts at 240 and does not dissolve it is likely PETG.

    We are a bit lost on a test for PETG. However we do know its melting point. Which is 240-260c. I would say it is likely you have ABS

    Once we know the material we can get to the meat of your question.

    Best way to proceed is to start with simple calibration prints. The thin wall. Cube, and part fitting. Once those pass you are good to go. Other than buying simplify3d I do not know of any short cuts. Back when I used slic3r I kept a spread sheet. I would change a temp by 5 degrees and give it a quality score. Repeat with speeds. Far as fan, I would expect that it wont effect much. Maybe need to calibrate your PIDs.

    Once you have it dialed in, all you will need to do is calibrate the temp when switching materials. Remember you need to calibrate even between different colors (okay its best to.. I often skip) I usually do the temp adjustments live on the printer. Increase and degrease a few degrees. For me the goal is to have the plastic as cool as possible. That allows for highest quality prints (ie less oozing and such)

    At 190 I can barely push it through the extruder at all. 210-215 seems to be where it starts to flow.

    Pla melts at 175ish so I am sure you do not have PLA

    I use a hot solder iron. Lower temperature than a lighter and still releases the PLA smell.

    Well your thermal couple / thermizistor might be over reporting. Updating answer.

    I assume you mean ABS in the middle of the answer? How about PETG? Is that eliminated?

    @SeanHoulihane I am afraid I do not understand your comment about ABS. No I do not say PLA and meant ABS in my answer. We have ID it as PLA from to the smell. Again not to say it is pure or of good quality. Here is more on PETG

    There is no pla smell...

    Its also very flexible (at least in a single layer), which doesn't seem to point to PLA.

    Yeah but you didn't actually burn it.. but if you burn it and it does not smell sweet the. No it won't be pla. Anything is flexible at 1 layer.

    "I have tried using acetone, and it dissolves roughly the same as some ABS I have" ---- Well this is the answer: If it dissolves completely in acetone then it's ABS. Neither PLA nor PETG dissolve in acetone. Some ABS brands have reduced styrene content to reduce the smell, also ABS doesn't smell much at lower temperatures. It takes 250C to make some of my filaments to **really** stink.

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Content dated before 7/24/2021 11:53 AM