Air Filter Updates & The Science of Air Filtration

I bought a 4000CFM fan to upgrade my DIY shop air filter! MERV 14 filters are also installed and the unit is tested thoroughly. The goal is to filter every last dirty micron of dust out of the air. Unexpected results follow! I'll also talk a bit about MERV ratings and the importance a high airflow. I also shed some light on the real world performance of DIY and Professional air filters.

Here is the link to the article where I pulled the "real world" CFM ratings for the PRO air filters:

_SHOPPING LIST_
Buy literally anything on amazon at this link to help support the channel with this link!

FANs

MERV 14 FILTERs (best small particle capture):
If you want to close off one side of the unit you can get away with 6 filters. 6 Filters should be suitable for the real world CFM of the fan but will reduce it's capacity especially when dirty.

MERV 13 FILTERs (almost the best small particle capture):

MERV 12 FILTERs (good small particle capture):

MERV 11 FILTERs (minimal small particle filtration):

_3D PRINTED PARTS (Build at your own risk)_
Air Filter Clips:
Drum Fan Clamps (pull config only):

_BUY 3D PRINTS (if you don't have a printer)_
Lots of attachments available!

BUILDING PLANS - BUILD AT YOUR OWN RISK!
Let me know if there are any issues anything.

I'm now on Patreon!!! The reward levels are very basic for the time being but I promise to bring merch and other perks in the future.

The 3D Handyman is a production of 2 Point Media. Stay classy!

[ncooty]

Damn, guy. Selling the discounted 3D-printed parts and providing free plans is really kind of you. Thank you.

[DNBingo]

I built the 8 filter version with the 2500 cfm fan for our non-profit Made4Me shop and it has made a significant difference to the air quality. We build adaptive furniture for handicapped kids using cardboard, which leaves very fine dust in the air when cut. Thanks for your work here!

[ytxuenf]

Lol I didn’t realize I was a nerd until it just hit me that I’m watching these videos while doing dishes and ONLY listening to the audio. You’re doing an incredible service for DIY peeps at home. Thank you so much man. ❤

[JesusChangesEverything]

Dude! How am I just discovering you! You are a real builder, well spoken, and your graphics make it soooo much easier to understand how it goes together. Thanks!!!

[harterobba]

This is a great DIY build! I built and have been using mine with the original orange fan for quite awhile now and can attest to its function. With some mods to the original plan, it is now even better. With an added filter on top of the fan to keep dust out of the motor, and a longer power cord/external switch, this unit keeps my small garage shop free of airborne dust. I have ordered the Cat black fan to upgrade the power of my unit. No more hacking cough after a day making sawdust. Thanks again 3D Handyman for putting this plan out for all to use.

[ncooty]

Impressive dedication on your testing rigs. Thank you, truly. That's a public service I know took you some time, effort, and money.

[skibamr]

Great stuff! This series of yourinspired me to rebuild my single-filter, box fan version. I love everything about what you've done here: good methodology converts specs into the real world. Thank you.

[zvezdankorica]

Great job and very nice of you showing the plan how to make it - keep up a good work

[RidgelineVanCo]

This is awesome! Thank you for making this video. Definitely going to build a few of these for my woodshop.

[classicalmockups]

Can't wait for the next addition to this series and seing the other versions in use

[johnhufnagel]

I don't know how the algo got me here, but i'm glad it did. I have massive attic work that needs doing, and it's beyond disgustingly dusty up there, especially after just having my roof replaced. I started using a lasko fan with a cheap 1" filter, letting it get sucked on the inlet side. it helps, but I can see building something better and letting it feed for a couple hours while periodically hitting everything with a battery powered leaf blower, is going to make my life MUCH less of a living hell. So thanks for that, and for convincing me to spend money. :D

[ThePolce]

Can’t wait for the rest of this series!

[logans]

I built box fan filters using 4 inch filters instead of 1, and they seem to do the job well enough, best budget option. You can even use more filters if you want more airflow.

[psyfusion]

Spent 3 years I. A commercial cabinetry and furniture shop and dust collection physics and mathematical formulas can become wildly complicated quick. Nice video and use a push stick always

[MakerDIY]

Awesome to see you doubling down on the content that worked for you! Just getting started with taking YouTube seriously and the 3D printed kits/parts for my projects was an avenue I was considering. It would be cool to hear about how well this works out for you on a monetary level and how you balance the workload of making videos and these parts/kits. Thanks for sharing!

[woodworksbygrampies]

Really, really awesome! 👍 Thanks for investing the time to gather all this data and information then sharing it with us. I'm "blowing"💨on over to your next video! 😂Take care and have a good one, Adios!👊

[kyleyates]

It's crazy how people come up with the same ideas all the time, I've done this on my intake for my old greenhouse i built in the basement. 2 box fans listed at 2200 CFM and 3 filters plus 2 more fans for the exhaust with another 4 inch filter to catch pollen. Works great, i should've gotten these bigger fans though cause these things kick ass

[JLoganMarshall]

A box fan has a fractional HP motor. Generally around 1/25 hp to 1/32hp. It's merely designed to move air, not draw it through static pressure.

A furnace blower on a 3 ton air handling unit employs a centrifugal fan with a 3/4hp motor. And it's rated to between 900-1300 cfm. I can provide the tables from the manufacturer upon your request.

Design of blades, and housing matters here. A fan meant to just push air with 0 static pressure and 0 resistance can use propeller blades. Exhaust fans get away with them because often the air they are moving is hot (think kitchens) and hot air naturally rises. So the fan is actually just directing it out a vent. Same principles with a chimney on a wood stove. You get good draw when the fire generates enough heat to start pushing up through the chimney. Until that point the fire can actually smother.

Air becomes denser (and heavier) when cold. Humidity also affects characteristics of air. All these things will change your fan's performance.

Try placing the Corsi Rosenthal Box filters in the tunnel and have the fan pointed into open air. Place your anemometer anywhere in the tunnel and check wind speed velocity.

In all air filtration systems emphasis should be on draw rate. Nobody cares about exhaust rate because that's filtered air. Measure draw rate.

Impelling dust into your box (pusher configuration) your anemometer will have a high velocity because it has 0 resistance. On the other hand your math equation won't have the huge surface area, but that's how the math has to be done. The design of the CR Box pulls air through filters, and thus resistance to flow becomes a factor. So you measure air flow drawn through the filters.

I have personally put a lit tea candle inside my CR Box. The air flow through the filters did not snuff the candle out. Made me scratch my head and realize the purported math was wrong. If you put a tea candle next to your AC's return duct it will snuff the candle out. A centrifugal fan is specifically designed to work when resistance and pressures exist. It also is designed to create a low pressure environment inside the return ducts. Further inducing house air to enter and go to your furnace, and A-coil.


GREAT JOB! I love your curiosity and willingness to investigate. You've the mind of a real scientist and critical thinker.

[Humongous_Pig_Benis]

You are correct when mentioning the long tunnel for allowing air to stabilize before reaching the fan.
It's called laminar flow Vs. turbulent flow. TLDR laminar flow it's like a quiet in-line fast flow stream of water (air is a fluid), and turbulent flow is chaotic, noisy and non efficient.
I've built my own filter for my workshop and have done some research beforehand, and from what I can remember the minimum distance between the filter and the fan should be 10Cm (4" in _Freedom Units_ ).
Nice video and keep those fingers away from that saw blade, *yikes* !!!

[ekek]

I'm eagerly following this filter series! Im interested for the potential of low cost DIY air purifiers for general home use. Ive not had luck finding a fan thats ideally affordable, powerful, quiet, and energy efficient. The centrifugal fan in the Coway Airmega 400s purifier is pretty good, whatever that one is. Rated at 410CFM of HEPA processed air drawing 69 watts. The downside is the ~$400 price tag and high replacement filter cost times having one in each room.

Your videos are giving me good info.