This is a follow on design from my V5 fan, again using a PC fan but this time a nice quiet Noctua 4-wire fan which makes it very quiet and simplifies the control.
Like the last one this design uses elements seen in wind tunnels: the main elements of this are the corner cascades, these are curved “wing” sections that turn the flow around the 90deg corner with low losses, they also straighten out the flow from the fan and make it smoother which is a bit more pleasant when it points at your face. This version is, however much easier to print and much more modular than V5. For more detail on the reason the cascades are there you can have a look at the previous version but in summary - looks interesting and works well
This version has variable angle which makes it much more practical, if you want to aim at a specific height it's much easier than with the fixed base of the previous design.
The fan is very modular so you can print what you want and perhaps design your own parts, it uses the hole spacing from a PC fan throughout so parts are relatively easy to mix & match. I've included the OpenSCAD file but it's a complex set of modules, with some bonus designs for different nozzles included.
You'll find a box body and lid that I use for micro controller to manage the speed of the 4 wire fan, if you want to use this approach you'll need to do some programming and soldering.
This version is designed for a 25mm thick fan, thicker fans may not be consistent with the intake and mount design without modification of the OpenSCAD to make the pivot arms longer
The parts are all designed to be fixed with M3 screws, some have nuts and some are tapped directly into plastic. You'll need a selection of M3 socket cap screws & some nuts:
I use a 19V laptop power brick for the fan and micro controller with a DC-DC converter to produce 12V. If you have a 12V power supply you should be able to use this directly. The electronics box has a hole for the socket that I used, you will need to use one that fits with your supply.
The fan I used is a Noctua NF-P12 redux, it's a 4-pin fan so it needs a speed signal which is generated from a micro controller. At full speed it claims 1700 RPM and it's very quiet at that speed but produces a good stream of air - it won't blow lots of air right around a room but it's very good for pointing at a person. Any other 25mm thick, 120mm fan should work but I would recommend a 4-pin fan and in general noise and airflow are more important than static pressure since there's relatively little back pressure in this design.
The micro controller I used was an Arduino Uno. I also used a set of 4 through-hole tactile switches for three-speed and off fan control fixed to a generic perfboard mounting PCB. Everything is connected with stranded wire with some connector pins, heat shrink and tape insulation
For the pivot I used some 10mm flanged bearings with 3mm inside diam I had available, it doesn't really need bearings but the design includes them because they were right there. These could be replaced with printed bushings but I didn't design these
The angle adjustment is done with an eccentric cam that is fixed to the side arm. This fixing needs to be firm to allow enough friction to keep the fan body at the desired angle. I found that this was best done with two nuts that could be tightened against each other once the correct friction is achieved.
Some holes are tapped for M3 threads so you will need a 2.5mm drill bit to ream holes ready for tapping and a tap. I recommend a spiral flute tap and tapping only by hand, it is risky to power tap in PLA since temperatures can easily rise too high
You'll also need a 3mm drill for holes that do not need tapping
Use a hex driver for your screws, again I recommend fitting screws by hand, not with a drill as PLA can easily get too hot and you will anyway not need high torque
Most parts print without support, the exception are the standard and reversed side braces that need support under the suspended section
Print settings are unlikely to be critical for most parts but strength and stiffness are important for the mounting parts (6, 7 & 8) so a thicker top/bottom and 3+ perimeters would be useful (but not required)
I printed all parts in PLA, which worked well although I used a silk PLA which required greater care than normal around reaming and tapping holes because I found it had lower layer adhesion than standard PLA
Some parts will look a little different to the ones in the photos, this is because I've altered some designs to improve things
I've supplied the Arduino code that I used to generate the 25kHz PWM frequency that the 4-pin fan I used needs. I think most 4 pin fans need this kind of 25kHz signal and this is not standard on Arduino (I think the standard PWM frequency is only a few hundred Hertz, which is way too low and the fan will ignore it or work incorrectly)
I set up the Arduino with 4 tactile switches connected to pins 4, 5, 6, & 7 which are set to use the internal pullups to be pulled high. The other switch terminals are connected to ground so when the switches are pressed the pins are pulled low.
The fan PWM connection is made to pin 9 - it's important to note that the code requires the fan to be connected to either pin 9 or 10, I think others won't work.
Grounds are connected to a common wire. 19V goes to the positive input of the DC-DC converter and it is adjusted until it produces ≤12V (not above 12V, the Arduino won't like much more than 12V so err on the low side if you're unsure). 12V goes to the fan positive and the Vin pin on the Arduino so they both get power.
The 4 switches are off, low, medium and high - the low setting is a very low breeze and the fan is all but inaudible on my fan. High is full fan power which is still very quiet but audible and produces a steady smooth stream of airflow that stays focussed even across a room
The OpenSCAD code is set up to show you an assembly of the parts by default by calling the “assembly” module, this might be useful for reference. If you'd like to change the designs of any parts you can check they all still fit with this module. Once you're happy the individual parts can be rendered for printing by commenting out the assembly and uncommenting the individual part needed in the section below
Please note: the default settings for the level of detail in the parts for rendering is VERY HIGH, these parts were designed for the use of one of the OpenSCAD development snapshots (which I have found to be very reliable: I'm currently using OpenSCAD 2024.02.11.ai18430 under Linux Mint) with the Manifold renderer, if you use the standard version you will need to change the level of detail down by quite a lot or you will have a long wait
The levels of detail are set to be lower on preview than render, if you want to change this the lines to check are:
detail = $preview ? 50 : 200;
...
bladeChordDef = $preview ? 12 : 40;
bladeSpanDef = $preview ? 14 : 60;
For the standard version of OpenSCAD:
detail
value on render needs to be changed from 200 to 100 or less - this affects most parts via an $fn
value set by this variablebladeChordDef
render value should probably be no more than 30 (from 40) & bladeSpanDef
render value should probably be no more than 40 (from 60) - these affect only the vanes in the flow pack
The author marked this model as their own original creation.