BOX FAN AIR FILTER For About $40! (How To Build a DIY Box Fan Air Purifier With HVAC Filters!)

Great video to highlight the dangers of fine wood dust particles! Just a couple pointers as I've done many experiments with my own box fan filter:
1. Charles Cox has pointed out to not overwork the fan. To add to that, clogged filters will actually force the box fan to pull air from the FRONT corners of the fan, just to blow it out the middle, effectively bypassing the filter media behind it. When this is the case, the box fan is actually counterproductive as all it's doing is blowing dust around the shop.
2. To avoid frequently clogged filters, use thicker filters than the standard 1", if possible. (I use 4" filters) Thicker pleated filters have more surface area of the filter medium and therefore can "collect more" dust. In practical terms, you won't need to change the filters out as often.
3. Try going to a local HVAC supply store (typically for professionals) and start a cash account with them to buy filters. I get mine for a fraction of the cost at big box stores.

Instead of box fan, is it alright to use inline duct fan? As I got access to cylinderical filter for cheap

I’ve been struggling to find a filtration system that could work in my small shop and have storability. I think your idea is it! Thanks for sharing 😊

Enjoyed video - learned a lot of the why and what for. thanks

OKay... quit drinking the kool-aide on the problem with wood dust and lungs. I've read all the studies. Not someone else's conclusion of the studies. But that actual studies. It's part of what I do for a living in Research. The problem with wood dust being a health hazard is very very small. Now, unless you already have lung issues from smoking or are allergic to certain wood species. You are not in danger of wood dust. These dust collectors you are speaking of... just help keep the dust down in your shop. Those manufacturers are taking the one tiny element out of the studies to scare people into buying or building these things for health reasons. They are lying to you for the sake of making money. Always follow the money. But if you want a really clean shop with less work... by all means get the filter systems.

If I get this built well, it might just turn out to be my hubs’ most prized anniversary gift ever. 🎉

I like your design Ethan. Specifically, the taper and the channels for the filter.

Great idea not just for wood shop but construction sites etc. nice build 💪🏽💪🏽

I built a box fan air filter works, a while ago its works great! I have a shop vac but don't use it to collect saw dust off my saws. I have my saws just hooked up to used regular household vacuums I picked up at garage sales and thrift stores. I just do wood working as a hobby. Just my way of saving money. It works out well.

I’ve seen these before, but they have the fan pointing inward

I like it. Simple & effective. Simplicity & low cost increases the odds that you’ll make & use one.

A better design is putting a floor drying fan, in a box with a sealed outlet, with a size of the box to fit one of those air filter panel. The fan will move air more efficiently, clear the area much faster and the fan will live forever because the bearing is going to remain completely clean being sealed in the box.
You can also use UV/Ozone bulbs in the box to disinfect the air if needed. I had to make this impromptu because i needed to take care of black mold, and didnt want to spread spores around. Box fans leak air around the blades .

OR....you can just tape a filter to the intake side of the fan, $.10

I have wondered what level of filter to use for shop air filtration. MERV 8? MERV 11? Obviously trade-offs for higher filtration, but the question comes down to "What size are wood dust particles and how small do we need to worry about?"

Really great! I saw a video just yesterday about how to build the four filter Corsi-Rosenthal box. I immediately started thinking about how much more practical they would be if they were in slots in a frame for easy mounting and changing. This video is just what I wanted to look for, so thanks a million for showing your version.

i notice you put the filters behind the fan, I usually see people putting the filters infront of the fan. so does it make a difference?

soooooo good!!

Do you have the plans available for the project?

One of the neatest, organized, cleanest, tools shops I've seen. Did you prep this for your You Tube shoot?

Great idea, think I could use a small one in my home...always so much dust flying around.

That’s gotta be really heavy

LOVE this. gonna build this asap

I've seen different designs and am not too sure of the pro's and con's in regards to fan direction.
Wouldn't it be better to flip the fan so that the dust inlet becomes the fan side and not the filter side? Won't this increase inlet strength?
If anyone knows the pro's and con's of this idea, please let me know.

thanks for the content

great video and great design.

A year ago I started home renovations and woodworking. I was really thankful for your video on air filtration, and built one that’s very similar. Since then I’ve realized my air filter really needs to be improved.

It would be great to see an updated version of your videos, with a mobile air filter (that’s easy to transport) and a stationary version for the shop that can quickly clean the air of the smallest particles.

simple idea, great explanation, informative useful video thanks a bunch

Awesome! Thanks for the I formation. 👍

are there any 3d printed clips for this

Great video. I just came across a 500cfm air scrubber exactly like the one you mentioned at the end of the video. Can i use that for regular woodworking?

I’ve thought of a slight variation to this for the basement workshop, so I can hang it from the ceiling - essentially to make the angles of the trapezoid much stronger angles, so the whole thing is much shallower, and hang it from the joists right above my work table.

Any thought as to which way the fan should go? You have it drawing through the filters here - i.e. blowing air out of the box - and I’ve seen others do it the reverse. I think sucking into the box (blowing out the filters) is better for being less obtrusive while working (not blowing air at me constantly), but it is drawing dusty air through the fan motor - surely that will reduce the life span of the fan. But for $35 for a fan, maybe not a huge deal. Thoughts?

Plant more trees as well🌱🌱🌱🌱🙏

i was just duct taping filters directly to box fans which i had 2 of. this i a little nicer looking

very nice, using 2 filters in a triangle formation. genius

I like this idea. I watched vids about using cardboard to tape a three sided box together. Seems short sighted; when the filters get dirty you have to destroy the entire thing and rebuilt it which is kind of tedious to begin with. The old saw sort of: build once, cry once. Something like that. I don't even need this. I cut everything outside of the shop and if anything, I can use the leaf blower or small fan to blow the dust away. If I do anything inside, I'm wearing a dust mask. I am way more concerned with my lungs than whether the shop looks neat and clean and when it needs cleaning, full respirator and leaf blower with all the windows and doors open. I don't mess around.

Thanks, I’ve always Ben thinking I need to spend hundreds for proper filtration. Also you explained well the hi volume low pressure vs low volume hi pressure. Been hearing that lately from other forums, and now I get it!

Interesting tutorial for dust allergies but if you want to get it right, just get a powered airfared respirator, or have some serious air extraction blowing air into the rub as well as out. Also be mindful that MDF is a lot more harmful than certain woods. Good luck

How do you tell when the filter on the box fan is at the point of needing replacement?

I wanna build something like this that can attch to a small badement window. I want to exhaust the smell and dust outside. Do you think building something like this and channeling it, whether with wood or even a slinky duct would work? Only one eay to find out and tweak lol. My workshop/lab needs it to filter sawdust and animal smells.

Not sure if you’ll see this, but wanted to let you know about the “C-R” or Corsi filter. An earlier comment here mentioned a filter system on “this old house” that used 4 filters in a box formation—it’s that. Two university engineers came up with it and it’s been shown to work as well (if differently) as commercial systems.

Basically: if you needed more affirmation that this is a good idea and of your own clever resourcefulness—engineers say you’re right.

Though I’d also be curious how you’d improve your own design from some of the reasoning behind theirs. For example, commercial systems are more efficient—cleaning 80-90% of particles—but your approach is just so much faster that it can compete with them at a fraction of the cost.

I made a dust collector out of a few 5 gallon buckets, lining up the perfect spinning airflow for the intake well also being two buckets tall made it so no dust making it out of the bucket system into the shopvac (actually never have to empty or clean the vac itself but I keep checking it anyway even though nothing ever is in there lol).

But I do have a box fan hanging from the ceiling sucking up with a filter taped (and sealed with vinyl tape) so it sucks up into the filter then blows against the ceiling and then back down circulating. I regularly vacuum the dust out of it though just to make sure im never taxing the fan. I find it very useful on just about any project sanding, staining, painting or even just using windex lol its good about fumes and smells, I avoid anything toxic as much as I can since I can only wear masks for extremely short periods of time but even non toxic/non fine things are still bad to be constantly breathing in so a box fan filter is a must in my opinion!

Great idea

Yes it is very helpful. Use a garage and a back room as my workshop and tired of dust all over everything.

Covering the corners of the fan (outside the circle)will help increase the draw

more effective than a Dyson?

Should the fan be pointed toward you or away from you while working