Duplicator D9 fan duct

Here's the result of uncountable iterations of trying to improve the part-cooling fan that comes with the Wanhao Duplicator D9 (MKII 400). It's supposed to fit the original 4010 fan without having to disassemble anything. Just use 2x M2,5 screws + nuts to attach it.

First I asked myself why wanhao didn't put more effort in their part-cooling design. Now I understand... the original duct-less design is good enough for almost everything. If you still want to try a fan-duct, you can choose from 3 versions (with names to reflect their appearence):

• the poo: This one comes in a rather organic shape (to use an euphemism) and was designed in Blender. The first examples looked quite nice but in attempting to improve the airflow I had to change it over and over again... eventually looking like a piece of crap. However it actually works. Not much better than without a duct though.

One problem with these 4010 fans is their uneven distribution of flow; from measuring the air velocitiy on one of these fans I found out that it's ~75% drop-off from one side of the outlet to the other. Plus there's (most likely) a swirl, which I wasn't able to measure exactly.

So I started over completely, utilizing flow simulation and parametric CAD. Here's the result:

• the vortex: As the name suggests this one creates a vortex with the "eye" just at the nozzle. This one is almost useless in terms of part-cooling (decreases air velocity more than duct-less), but it's a way to prevent cooling your nozzle.

• the pincer: This crab-pincer shaped version is supposed to have decent airflow just below the nozzle while not obstructing the view on the extrusion. This one works kind of. Still not overwhelmingly better than the duct-less design, but it's fine. I half-recommend this one.

BTW: The picture of the pile of failed designs shows just a fraction of the actual fails. Most of them went directly into trash after trying. I know this is nothing to brag about but I think some people might relate to that, which is why I uploaded that too.