Velocity stack for Noctua 40mm fan NF-A4x10

thingiverse

I upgraded my Monoprice Select Mini's fans from cheap 30mm units to 40mm Noctua units. I discovered a great design for a velocity stack for 40mm fans that I was going to print out, but found it had a larger center hub cover than the relatively small 17mm motor hub on the Noctua fan. Several people asked for a Noctua fan version, but the designer didn't post one. I downloaded the STL and used MeshMixer to resize the center hub to 17mm, printed it out and discovered it worked, so I tried to post a remix, but found the original design had a "No Derivatives" license. I commented on the original thing that I had a modified version for the Noctua and could supply it, but no interest from the original designer. I was recently contacted by someone who wanted my modified STL, so I sent it to them, but then wondered if I could completely redesign the item from scratch in Fusion 360. I've been constantly trying to improve my skills in Fusion 360 and this looked like a great challenge. So, here's what I came up with, and the results look really good. Since this is designed from scratch and takes inspiration from several sources, it's not a remix and thus isn't in conflict with the no derivatives license of the first one that I printed. Note that there's no math behind this design, I just used elliptical curves and measurements that looked cool. Does it actually increase airflow? No idea, but it looks really cool. Also, since I drew one support leg and then patterned it, I realized I could skip the pattern and have a minimal single-leg design, which again - looks really cool. That design has provision in the back for a 3mm pin, but I'm using it with only one screw and simple friction holds it in alignment. I also printed out a twin-leg design. Obviously the four-leg design is the most secure, but I can't imagine that four M3 bolts to hold one little 40mm fan in place are absolutely necessary. I've also included versions with a 22mm and 25mm center hub to work with fans with larger motor hubs. Only posted those in the four-arm design, contact me if you'd like a single or twin-arm design or need a different hub diameter. Including the F3D source file. In theory, this could be used to make velocity stacks for other sized fans, but I was having some issues driving the elliptical cross sections in the profiles, so no guarantees they'll behave properly. If you do remix it for a different size, please post your thing and list this as a remix, I'd love to see it!