The first part of the solution is this custom fan mount and improved duct found here. This improves airflow but is, IMHO, still targeted at printing PLA. I find that a general cooling solution like this one is extremely hard to tune for ABS...too much air flow and your part comes detatched from the build platform, unless you have its temperature cranked and then you risk warping. Too little airflow and you miss the whole point of having a fan in the first place...to solidify details as they are printed!
What I really wanted was the same kind of ducted fan that I have on the Wanhao Duplicator 4S! I don't have the design skills, or tools, to modify the above model so I designed a parasitic attachment to focus the output of the fan on the area right below the nozzle. This also has the advantage of being easily removed when I print PLA, which is most of the time on the UM2.
The major issue with this design is that of MELTING! Over time the part does warp and I have to print another one. The solution to that will be to have one printed on an SLA device in resin. You can not really tell from the top picture but that is a part printed in resin for the same reason.
In a later post I will talk to the need for a fan when printing ABS.