I have printed both PLA and ABS on my ultibots MK. It prints both well with no specific problems noticed so far. Ultibots has begun shipping their machines with a combination hotend/print cooling duct/fan system in place which helps tremendously with printing PLA and with finely detailed ABS.
As for the fumes associated with ABS. There has yet to be any scientific evidence to show the "fumes" are harmful. Some people are more sensitive to it than others and prefer not to smell it. That's find and to each their own. Experience it for yourself. If you're printing in a phone booth then you might not like it. If you are in a big room then you may not even notice it unless you are right over the machine. At work, people occassinoally mention a smell after I've been printing for 6 hours in a relatively small (20x20) room. I don't smell anything and lots of others don't either. PLA just smells "sweet" when printing.
Let me know if you need any help with that MK. I built mine off and on over a week or so and had it dialed in and printing the first calibration cube (very successfully) in about 45 minutes.
As for the fumes associated with ABS. There has yet to be any scientific evidence to show the "fumes" are harmful. Some people are more sensitive to it than others and prefer not to smell it. That's find and to each their own. Experience it for yourself. If you're printing in a phone booth then you might not like it. If you are in a big room then you may not even notice it unless you are right over the machine. At work, people occassinoally mention a smell after I've been printing for 6 hours in a relatively small (20x20) room. I don't smell anything and lots of others don't either. PLA just smells "sweet" when printing.
Let me know if you need any help with that MK. I built mine off and on over a week or so and had it dialed in and printing the first calibration cube (very successfully) in about 45 minutes.