Can a Prusa print ABS reliably?
I currently use a Printrbot and always wanted to print ABS.. But even after adding a heated bed, it was just impossible as the bed will only get to 80 degrees so I gave up.
I saw a lot of projects where people added enclosures but it was too much effort, so I stuck with PLA.
But I always knew that when I bought my next printer it would have to print ABS, and was considering the FlashForge Creator.. But the Prusa seems to be a better choice, but as its un-enclosed, I fear that ABS may be problematic.
So can the MK2S print ABS in free air consistently without any other mods?
Jon
Re: Can a Prusa print ABS reliably?
abs generally is not easy to print, due to the warping that comes with it.
did you try the EasyFil ABS ? I just came across this abs filament recently and got very good results when printing at 240°C/80°C, even without an enclosure.
but you've asked if the prusa can print abs reliably ?
the best answer for this is the fact that most of the printed parts for the prusa printer itself are printed at a "farm" of prusa i3 mk2(s) printers.
so I guess that we can call this "reliable".
of course this farm has it's own environmental conditions and I guess that it's a little bit warmish compared to my own shack (but maybe not, my printer is located under the roof). 
dem inscheniör is' nix zu schwör...
Re: Can a Prusa print ABS reliably?
I print most of the time with ABS. My answer is YES, it prints reliably ABS. There are several topics in the forum talking about ABS. An user gave different interesting tips to print successfully with ABS but I don't remember where. You can see some succesful ABS prints here: https://www.youtube.com/channel/UCz-zQZcKcvEDdd9C9hOKYWg
My youtube channel about the Prusa I3 MK2 https://www.youtube.com/channel/UCz-zQZcKcvEDdd9C9hOKYWg
Re: Can a Prusa print ABS reliably?
Like you, I had a difficult time printing with ABS at first. Now it's all I print with. I like ABS because you can easily join parts together with acetone and it holds up well in hot environments like a car.
There are several tricks to successfully printing with ABS, many of which you will find on this forum. My main go-to tricks are:
1) As others have said, the first layer is critical. Get that right and everything else will likely fall into place. I found I have the best luck by adjusting the live-Z EVERY time. I wait for the 9-point calibration to almost finish then I get ready to do the live-Z. As the printer is laying down the perimeter I adjust the live-Z. If I'm too slow or don't get it right and my print starts out crappy, I just abort the print and start over. I'm getting to where I'm successful about 95%? of the time. You can always add additional perimeters to give you more time before your actual print.
2) Surface prep is important. I usually clean with ABS maybe every 5 prints or so and most times I prep with IPA. I also use IPA immediately after using acetone. I find I have a tough time getting things off if I use strictly acetone.
3) For most every print I design in a little attached circle, roughly 15 mm in diameter (or whatever I feel like that day) to my object to be printed. I make the thickness 0.2 mm and I make sure to rotate the little circle toward the front of the printer when I lay things out in Slic3r. I might put a circle on two sides if the print is large. After printing I dive in using an inexpensive scraper with a sharp edge. Keep it parallel or you'll be replacing the PEI (I'm convinced if you haven't replaced your PEI yet you're either a liar or you haven't printed much.) I always remove my prints while the bed is hot (100C). If I printed last night and the bed is cooled, I turn on the bed and let it heat up for at least 20 minutes or so. I want the bed and print warm. Go slow, go flat, or go "shit!"
4) Regarding enclosures. I have an enclosure but this time of year (Colorado, garage, hot) I leave the door and the back open. In the winter I close things up and may even need to preheat the enclosure before the printer will turn on. I monitor the enclosure temp via sensors that communicate with my phone (overkill - a cheap thermometer would work just fine.) If it gets over about 105F I open things up and cool it down a bit. I haven't had problems with curling but I could see where drafts and such could cause problems.
5) Filament. My go-to filament is Hatchbox white ABS. I like it because I can easily see how the print is going, it's easy to paint, it's inexpensive, and it works. I use black ABS quite frequently - others infrequently - but I love the white for most purposes. I leave the Slic3r settings at the default Prusa ABS settings (255/100).
Good luck and happy printing.
Re: Can a Prusa print ABS reliably?
I print ABS reliably, without an enclosure, just fine. Your mileage may vary depending on your environment. I live in the NW, normally it is rainy, although recently have been running AC. The printer is in a spare bedroom, door closed, AC vent closed so there are no cold breezes. The ambient temperature in the room with the printer keeps it decently warm, not hot, not cold (key is make sure no cold breezes).
For the first time when switching from PLA to ABS. I used 2000 grit sandpaper to rough up the PEI. Then I cleaned it using windex. Don't use alcohol to clean the bed when printing with ABS, use windex for PETG and ABS. Usually running about 240-255 for the hotend with the bed at 100-110 (depends on which brand I'm working with). Make sure the fan is off during your prints.
After you remove the print, clean it with windex again. Then print again.
Re: Can a Prusa print ABS reliably?
With my first generation Prusa (Do we call it a MK1 now?), I had much nicer quality printing with ABS than with PLA. Perhaps it was all in the settings I used, but it seemed like ABS just worked better.
Can't say with the MK2 upgrade yet since I've not quite sorted it out.