My experience printing with ASA filament
I'm new to 3D printing and decided to start with one of the more advanced materials, ASA. I like optimization and since the price of ASA can be compared to PLA¹ while having much better durability and UV resistance, I wanted to go straight to that material. That's also why I opted for the Prusa Core One+: It can handle ASA and is made in the EU.
Since it took me some time to figure out how to get around the quirks of ASA by both adjusting my print settings and other tweaks, I'd like to share my experience so far.
First of all, a word about safety. Don't put your printer in your bedroom. I put it in the basement near a window and I recommend having it open while printing. Styrene poisoning could be dangerous, so it's better to be safe than sorry.
The Department of Health and Human Services (DHHS), National Toxicology Program (NTP) listed styrene as "reasonably anticipated to be a human carcinogen" in the Report on Carcinogens, Twelfth Edition, released on June 10, 2011.
— cdc.gov
I was amazed at how well ASA can handle bridges. I could easily bridge 4cm gaps which combined with the higher strength means that I can print many things with 0% infill while still being quite strong. Also ASA can be sanded and polished really well to a point where you can't see the difference compared to an injection molded part. I still need to try out acetone vapor smoothing and will update this post when I get to it. But I would recommend doing it outside such that your filament spools don't glue themselves together.
ASA really, really likes to warp under certain conditions. Not always! You can optimize 3D models for ASA printing. Features that like to warp the most are curved overhangs. The ones you find on the first 10 layers of Gridfinity bins for example. Round corners that expand outwards. Warping is made even worse as soon as the print fan starts spinning. I recommend turning the print fan off entirely. ASA is printed at 255-265°C in an enclosure at ~45°C, it cools down quick enough by itself. To do this, modify the filament settings in your slicer to disable the fan for the first 1000 layers. Another trick I learned is that you can increase the time per layer to let the layer harden to reduce warping by printing more of the same thing at once. That way, the new layer can't pull on the layers underneath as much.
I'm using the Prusa silk (sand blasted) steel sheet and warping can cause a print to deform and come off this print bed. I first tried using a brim of 5mm, which does improve it, but it only really helps to hold it down. A brim did not prevent warping entirely. What did massively improve bed adhesion was applying a decent layer of a regular white glue stick (mine is solvent free and the cheapest paper glue you can find in a store). When I tried to remove a small 1x1 Gridfinity bin, I almost lifted the steel sheet with it. I applied the glue stick as two thin layers. After printing, wipe off the glue with IPA. You can probably also use warm water if you dry it afterwards to prevent it from rusting.
Depending on what color of filament you use and specifically what pigments the manufacturer uses, you might need to lower the printing temperature. The default in Prusa Slicer is 265°C, but I noticed that my white filament ordered from orbi-tech started to form bubbles and turn brown. Lowering the temperature to 260°C resulted in no discoloration and the prints came out just as good.
ASA is relatively hygroscopic. After it was raining for one day while I was printing, I noticed many bubbles forming in my 3D prints after a few days. The filament had absorbed the ambient moisture. After drying it in a dehydrator at 50°C for 2h, it was dry enough to print at a good quality.
What are you experiences with this material? Are there other plastics I should look into printing with? I'm only around 2 weeks in to this hobby and would like to learn more.
¹ I compared 5 local German producers (not resellers) of PLA and ASA filaments and ASA is around 27k€/m³ compared to PLA at 21k€/m³. I'm using k€/m³ for a proper comparison independent of material density.