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I'm thinking of recycling some filament from a couple of recently failed prints. I can reuse them in the future for basic prototypes, so I'm not concerned with whatever weird mixture of colors come out (they are of a few different colors).

The thing is, I have both PLA and ABS, in small quantities. I originally intended to simply use each one separately, but it occurred to me that they could be mixed.

If I recycle PLA and ABS together into one strand of filament, will there be any negative side effects (e.g. reduced strength)?

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This is not a good idea. Both filaments have different melting points, that of ABS being much higher than that of PLA. To melt the ABS you have to heat the plastic to the point where the PLA starts to degrade.

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    $\begingroup$ While I agree it's not a good idea, I don't think it's completely improbable. I've had success in the past with printing ABS and PLA (separately) between 220-225C with no issues printing. In the end, if you combined the two materials, you would need to relearn what extrusion temperatures work for the new material. You'll probably lose a lot of the strength of ABS and rigidity in the PLA by combining them, however it would be a nice cheap alternative if you have a bunch of scrap material and need a simple knick-knack. $\endgroup$
    – tbm0115
    Apr 5, 2016 at 14:07
  • $\begingroup$ I think this answer is factually incorrect, since PLA won't degrade up to 250 °C and blends may print properly even when colder than the pure components, e.g. PC-ABS. The difference in melting temperature PC and ABS is as big as PLA and ABS, yet they work. You may be right for other reasons, but the explanation you provide as basis for the answer is IMHO wrong. See my answer. $\endgroup$
    – FarO
    Aug 18, 2021 at 9:13
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Simply put, PLA and ABS should not be mixed into a filament.

The most common issues most printers experience, such as delayering, warping, etc., are addressed completely differently based on the material you are working with. There are many examples of this, and I will attempt to go over some of the basic ones.

You will have extreme difficulty getting proper layer adhesion. Assuming you have a level, flat, semi-coarse (helps) surface for the first layer, the recommended heated bed temperature is 70C for PLA. With ABS, you will experience warping by the 5th layer at that temperature. ABS prefers 110C for a heated bed, and 80C for a heated chamber (personal experience for most reliable results). Next issue is going to be delayering and stringing. There is no happy medium! Matter of fact, the number of issues even attempting this is almost too many to list. The quality will be complete garbage. On one hand you will have delayering, warping, and jamming of the ABS when set to PLA specs, and stringing, leaking, etc., when set to ABS specs.

I hope this helps.

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Mix 'em, let us know how you go. You're unlikely to damage your printer, and you're only 'wasting' scrap.

I suspect that if you mix in small quantities of ABS (30% or less) you'll end up with a PLA mix similar to a 'wood' or 'metal' PLA filament.

To that end, recommend trying to print with PLA settings first, and going from there.

Make sure you let us know how you go, it'll be real interesting to see the results!

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CNC Kitchen tested PLA up to 265 °C or 270 °C in a couple of videos, for example

The plastic (it may depend on the brand) holds just fine up to 250 °C, but (from personal experience) bridges become really difficult to tune. Strength is very good.

ABS can be printed properly starting from 235 °C (depending on the brand). At 235 °C layer adhesion may be suboptimal, but you are mixing it, so it's not obvious that the result will be poor.

So, to summarise you have a common range 235-250 °C where you can print both plastics properly when pure, so it is reasonable to think that by mixing them you will have at least the same temperature range (the bottom may even be extended a bit, as it happens with PC-ABS which prints properly colder than pure PC).

So I would say that it is a worth test with likely positive results.

In fact, ABS-PLA blends exist and are very good blends for industrial use as the Terrafilum site states:

ABS_PLA_Blend

Strong PLA Industrial Grade PLA with superior flow and strength performance; designed for parts where PLA is desired but where the parts will be subjected to repeated use; ideal for parts that may need bend slightly without breaking during use.

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    $\begingroup$ If the amount of ABS is kept low, OP basically just reinvented generic-brand "PLA+". :-) $\endgroup$
    – R.. GitHub STOP HELPING ICE
    Aug 18, 2021 at 14:24
  • $\begingroup$ Or, OP also just re-created Tiertime PLA $\endgroup$
    – Trish
    Jan 12 at 7:24
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First, I print ABS and PLA models. I have accidentally printed PLA at ABS settings with absolutely no strange effects (being printed at 100 °C heat bed and 225-240 °C extruder temperature). If the mixture is truly homogenized together, I do not see a problem in mixing the two materials, however, the cost of a recycler and winder are still cost prohibitive. Like the above poster said, experimenting would be necessary to get the settings right.

Technically, it should work .

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  • $\begingroup$ Your model certainly must have deformed with such a hot bed underneath and nozzle above. 100°C is far above PLA's glass transition temperature, and I would also presume that if you are using an ABS profile your parts cooling fan is set to low or off, slowing the rate at which the hot plastic solidifies. $\endgroup$
    – William
    Nov 1, 2021 at 19:23
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yes but you would have to experiment with the settings to see were it afectivly melts.

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