Things you should know about ABS

Things you should know about ABS

Next up in this series, ABS!

 

Ok, let’s start out with probably the most important bit about ABS: There’s not just one ABS, there are dozens of different versions that are all ABS-based or even just ABS-like. Let’s actually start with just ABS itself, which already isn’t just one thing. It’s acrylonitrile butadiene styrene, 

so three monomers, mixed together and linked together, forming the copolymer A-B-S. The Butadiene in this mix gives ABS its typical milky, off-white color; it’s a rubber, also used for car tyres and such, and depending on how the ABS is manufactured, it remains as larger or smaller particles within the mix – kinda like the small suspended fat particles give milk its opaque white color. Butadiene also gives ABS its toughness, which it is known for. Now, the other polymer in here is Styrene – and that’s the red thread that is common to almost all ABS-like materials. Now, just by varying how much of each component is used for the ABS blend, you already get a huge variance of properties, but since ABS is mostly an industrial plastic, it’s also really common to have blends with additives mixed in that will have it flow better into an injection mold, release more easily from the mold or change the properties of the final molded piece in some way.

And if you just get one of those blends and extrude it into filament, it’s not going to print well. While PLA is seeing a huge upwind with new blends specifically for 3D printing, ABS is already an established ecosystem and 3D printing doesn’t make too much of dent. What I’m basically getting at here is that ABS filament comes in an enormous range of qualities and properties and each one will want to be printed differently, and in cases where the manufacturer is using the wrong injection-molding specific blend to make filament, there might not even be a good way to print that specific ABS. So the quality gap is a lot larger than for PLA, as is the range of properties you can get out of it.

And what makes matters even more interesting is that there now is a huge range of ABS-like filaments out there, from the simplest HIPS, high impact PolyStyrene, again, styrene-based, ASA, basically replacing the Butadiene rubber in ABS with Acrylic, same stuff as acrylic glass. There’s m-ABS, which is ABS with less Butadiene in it, making it a transparent plastic with a lower impact resistance, you can get PC-ABS, ABS blended with Polycarbonate, or you can just get polycarbonate by itself, and I’d still consider that to be similar in printing properties to ABS.

 

So, yeah, properties, what are those? What you’ll typically hear is something like, oh yeah, ABS is strong, temperature-resistant, but it warps and smells. OK, let me get this straight. Parts printed ABS and ABS-likes, except for maybe polycarbonate, are typically weaker than most other plastics. Especially if printed wrong, like in a cold environment. That’s also where you’ll see ABS warp and crack along the layer lines because it doesn’t bond well enough to the cooled-down previous one. I’ve moved on to printing any ABS-likes exclusively in an enclosed chamber, the prints come out much stronger, and I don’t have to worry about warping that much anymore! Yes, the warping. As we touched on in the last video on PLA, having a material that stays soft longer when it cools down will also give it less of a chance to contract and actually warp your part. Because molten, printed ABS is already pretty hard when it has cooled down to about 100°C, as it cools down further it can’t stretch to make up for the thermal shrinkage as easily anymore, so it will want to pull your already printed part up like a dish. If you know you have good layer adhesion with your filament, you just need to get your prints to stick to the bed to somewhat counteract that. For bed adhesion, it’s hard to beat PEI, ABS almost sticks too well to it, some adhesives you spray or wipe on there also work well, but what makes a huge difference here is bed temperature. So yes, a heated bed, at least with my experience, is mandatory for printing ABS. We used to crank these babies up to 120°C, but with most materials, that leads to what is often called an elephant’s foot, and talking about nuclear meltdown here, but it’s when the very first layer of the print sticks well to the bed, but the bed is so hot that the first few layers above it end up staying soft and contract as the print progresses. A heated bed that is too hot will also ruin any overhangs that are close to it because those will curl up, so again, I can not recommend enough to use an enclosure and dropping the bed temperature slightly, maybe to around 105°C, and instead just having the ambient air in the enclosure at about 40°C. Any decent printer can handle that ambient temperature, even if you have non-PLA printed parts on it and the motors and electronics inside with the rest of the printer.

Print quality with ABS can be surprisingly good since mostly you don’t need part cooling with active fans and such. ABS and ABS-likes will print well if you just grab your PLA profile, turn off the cooling fan and adjust temperatures. If you get meltdown artifacts, like typically on the chimney of a Benchy, you might need to increase the minimum layer time, I usually run a rather long minimum layer time of around 25 seconds to avoid pumping too much thermal energy into a small section in too short of a time.

I wouldn’t try to “tune” any seemingly advanced stuff like extrusion width, I’d say not until you have temperatures and speeds dialed in, but usually your slicer will do a bit of math and figure out extrusion width and such out pretty much perfectly by itself. You might need to set the base speed manually, as ABS will not flow as easily as PLA and usually can’t be printed quite as fast. Though 60mm/s should be very doable with normal layer heights.

Now, you should only print ABS with an all-metal hotend, and I’ve often found that higher temperatures will actually improve print quality instead of degrading it. So if your hotend can handle it, feel free to experiment with temperatures up to, I don’t know, 265°C?

Higher temperatures also mean more emitted particles and a stronger smell. Not every ABS smells as bad as others, but in either case, try not to be in the same room as your working printer or printer enclosure and ventilate it well during or after a print. If you print a lot of it, you’ll find nasty cooked butadiene deposits all over your hotend and extruder, so I don’t think that’s all too healthy to breathe in. Then again, people still choose to smoke.

ABS is actually the prime candidate for post-processing. Paint it, glue it, drill it, mill it, tap it, weld it, or just smooth it, eherm, all that works. Because it has such a high working temperature, you can work with it with common metalworking tools no problem. One of the big advantages of ABS, at least in my eyes, is that you can cut it without it splintering or breaking – so if you print a part with a brim, which is highly recommended for anything ABS to make sure it sticks, you can either take a sharp knife and cut it off or use one of these deburring tools – link in the video description to cleanly take it off!

And for storing ABS, I know it’s not as sensitive to moisture as some other filaments, but it can still degrade, bubble and just make for overall horrible prints if it takes up too much moisture from the ambient air. So while you don’t have to store it in a drybox like Nylon, it definitely doesn’t hurt to keep it in a somewhat humidity-controlled space. So don’t just drop it in our shed during summer.

 

One last thing about ABS: ABS itself is also not UV resistant, it will turn yellow, degrade and eventually crack and break if left outside in the sun. So either you can use an inherently UV-resistant filament like ASA, where the plastic itself is not going to degrade, but still the colors might bleach over time, or you can just go with black standard, cheap ABS. Because the black colorant is typically based on soot, those tiny black carbon flakes will actually absorb UV light as well, so even though the sunlight still hits the very surface of your part, it will only be able to penetrate the very top layer, so the part itself will stay perfectly strong. This part right here I used as a brace for my apple tree for, what, five, six years, had it out all summer and winter and it looks, feels, handles exactly like new. Maybe except for the moss and stuff that’s in the creases here, but everything else is still perfect.

 

So overall, is successfully printing ABS, like, the big graduation ceremony for you that you can work up to? Well, not necessarily. There’s still a good bit of randomness involved with filament choices, especially with ABS, I’d say get some brand-name materials, for example from this series sponsor Aprintapro, I tested their flame-retardant PC-ABS in a Filaween episode and have been casually printing their other materials and it turns out they are actually making excellent materials, which is why they’re getting to sponsor these videos in the first place. The last few videos had the “contains paid promotion” banner on them, same thing, but it apparently wasn’t really clear why that was. All that means is that the Aprintapro products, right here, get a bit of extra airtime, I’m not required to praise their products at all, but still, their sponsorship in return makes it possible for me, well, us, to produce more content for you guys. Same as with the sponsorship from ATOM 3D for the stl-Bender video, the comment section on that video actually seemed really enjoy that part!

Alright, ABS has a great set of properties, but unless you need all of them, there are other materials that perform similarly but might be a bit easier to print – we’ll get to those in the next few videos. Still, if you have an end-all tip for printing ABS super reliably, please leave it in the comments below or post it in the forums so that others can learn from it. If you enjoyed this video, do this [thumbs], that [point to sub] or that other thing and I’ll see you in the next one!

 

Thank you to Aprintapro for sponsoring the series! Check out their filaments here

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