This is a helix fan duct for a 40mm fan with a blower, designed to redirect, shape and straighten fan's flow with maximum efficiency.

It is designed to be attached to Wanhao i3 v2.1 printing head with 2x 20mm M4 screws with conical cross heads, while the assembly itself is held together with stock M3 screws.
All threads in the holes print well enough with 0.2mm layer and match stock M3 screws.
The bottom most surface of this duct is designed to be at least 2mm from the print bed at minimum Z position.
I also designed appropriate supports, included in the model.

This is an evolution of my previous design with an addition of helix duct inspired by DaveGun's Vortex Fan Shroud. Like my previous design this one is a product of several CFD simulations.

The assembly consists of 3 parts:

• helix duct with a 40x15mm rectangular exit
• positioning frame
• blower duct

I designed it this way to make it possible to switch blowers without having to print the whole thing and also to make it possible to use this efficient helix duct on any printer or in any other application that requires air flow.

I've also included models of 2mm thick dampening inserts to be made from flexible material to reduce noise and vibrations from the fan.

Compared with my previous design this assembly provides even more flow (up to 4.3 CFM which is quite close to theoretical maximum of ~5.5CFM for a 40mm fan) and has much less adverse effect on the nozzle temperature level. It is designed to provide cooling for 2 zones - main flow goes around the nozzle and a limited amount goes directly beneath the nozzle through a separate channel, this allows to maintain high flow rate in general and provide cooling of just extruded material without causing too much temperature drop of the nozzle. I've also included blower version without a small channel to further limit nozzle temperature drop in case you don't need to print any severe overhangs or small parts. 4x 1,5mm holes provide cooling flow to prolong blower life under high temperatures (I printed it from PLA and used it to print at nozzle temperatures as high as 245-250C and it survived the print without noticeable damage).