Corsi-Rosenthal box for air cleaning in the shop?

[Anastasia Cheetham]

I have a dust collector that I use when sanding or turning very dry wood, but it doesn't get everything, and I still find that over time, a layer of dust appears over most of the shop. I suspect an air cleaner would help.

I discovered this Corsi-Rosenthal box design:

View: https://www.youtube.com/watch?v=hIuH-2naozI


It's basically a box make of furnace filters and a box fan. It was designed for COVID-related household air cleaning. I'm wondering if anyone has tried this for shop air cleaning. Any thoughts on whether typical furnace filters would be appropriate for wood dust? If not, what would you suggest?

Thanks!

 

[hockenbery]

I have a dust collector that I use when sanding or turning very dry wood, but it doesn't get everything, and I still find that over time, a layer of dust appears over most of the shop. I suspect an air cleaner would help.

It's basically a box make of furnace filters and a box fan. It was designed for COVID-related household air cleaning. I'm wondering if anyone has tried this for shop air cleaning. Any thoughts on whether typical furnace filters would be appropriate for wood dust? If not, what would you suggest?

Thanks!

There are several units available for shops Jet and jds are two.

I used a jds in a basement shop. It made it safe to breath the air 2 hours after a lengthy sanding session
It has a furnace style filter as a first stage and inside filter for smaller particles with pockets for more surface area..

There are lots of homemade copies - most are made by putting a squirrel cage fan in a plywood box and various filters on the intake side.

 

[Dean Center]

You can also tape a 20"X20" furnace filter right to the intake side of the fan. 20X24 works a little better. However, in my experience they don't work nearly as well as a commercial filter, as shown in Al Hockenbery's post. The filter cube might be superior, but also bulkier and more fragile.

If you're really ambitious, you can make a plywood enclosure with a squirrel cage blower/fan inside, with 1-2 filters over intake holes. The greater hp and air movement of a 10-12" squirrel cage blower and the more sealed enclosure should make them nearly as good as the commercial units. The squirrel cage blowers are commonly used in home heating systems, or in floor drying fans used by home fire/water damage restoration companies.

 

[Tom Gall]

I have a dust collector that I use when sanding or turning very dry wood, but it doesn't get everything, and I still find that over time, a layer of dust appears over most of the shop. I suspect an air cleaner would help.

I have a dust collector, a JDS ceiling system w/ added filter in front of intake, and a box fan with a filter attached. All of these are within 6 ft. of the lathe and do a pretty good job. I still get a very light layer of dust around the shop (probably caused by my use of an air gun) ... but maybe not as thick as yours!

 

[robo hippy]

I do put those filters in my bedroom windows during pollen season here. Mostly to keep pollen out of my bedroom. While they will work, having a good hood and a dust collector, not a shop vac, will work better.

robo hippy

 

[Mark Jundanian]

The Rikon air filters are on sale this month at Woodcraft.

 

[Lance Mirrer]

Serious sale at Woodcraft!
I have a modified HF DC at the lathe and two of the Jet air cleaners in a 3 car garage. The 2 jets are together and close to the lathe.

When I forget to turn on either the DC or Air Cleaners, I find lots of dust around the garage. With all three running, most of the garage stays clean.
When turning for awhile or sanding, I leave the air cleaners running for a few hours after finishing. Very happy with results.

There is also a mini split A/C unit in garage. And with all this I still wear a mask!

 

[Michael Anderson]

Lance, how do you like that HF dust collector? And, what modifications did you make? (and why)

 

[Lance Mirrer]

I like the dust collector. Biggest improvement is the air filter. I also.built a winn(spelling?) separator below the filter, and have a more efficient impeller which haven't installed yet.

So close, Wynn Filters https://wynnenv.com/woodworking-filters/
And for the science and lots of cool info, the guru of dust collecting is Bill Pentz http://billpentz.com/woodworking/cyclone/index.php

 

[Brian Nowak-Thompson]

You can also tape a 20"X20" furnace filter right to the intake side of the fan. 20X24 works a little better.

I use the kind of setup Dean described. It hangs right behind the lathe and works remarkably well. I've collected some dust particle data using this filter set up under a variety of conditions, and it effectively scrubs the shop air of dust in 10 minutes or less. It doesn't capture all dust but I find it will drop the particle counts in the shop below what I experience in other situations (both in and out of the shop). For the cost, there is no reason not to have one. Are there more effective ways to manage dust? Yes, but you pay for those with both money and convenience.

 

[Steve Bonny]

Another useful add to your shop is a particle counter. You will learn alot about what you are breathing in all day and how well your dust collection and air filters work.

 

[hughie]

Another useful add to your shop is a particle counter. You will learn alot about what you are breathing in all day and how well your dust collection and air filters work.

Good idea, I just looked up prices where I am. A bit pricey 400 for a basic and anywhere from 700 to 1500 for the others

 

[Steve Bonny]

Good idea, I just looked up prices where I am. A bit pricey 400 for a basic and anywhere from 700 to 1500 for the others

Yikes! I have the Dylos dc1100 pro, about $260 on Amazon. It's worked well for many years. Occassionally it has been reading unusually high and I thought it had gone wrong..... but it was right! Pin hole in dust collector bag. It will also pick up smoke if you burn something. Mine’s reading high in Iowa right now - its picking up the smoke from fires in Canada drifting over the country

 

[Brian Gustin]

Good idea, I just looked up prices where I am. A bit pricey 400 for a basic and anywhere from 700 to 1500 for the others

WOW! and here I was thinking about just getting a cheapo counter for 50 bucks (for me , in USD) on amazon.. figuring it would be "good enough" for an indicator/comparative tool, doesn't have to be scientifically accurate, right?
here ---> https://www.amazon.com/gp/product/B08M6F57PN

 

[Steve Bonny]

WOW! and here I was thinking about just getting a cheapo counter for 50 bucks (for me , in USD) on amazon.. figuring it would be "good enough" for an indicator/comparative tool, doesn't have to be scientifically accurate, right?
here ---> https://www.amazon.com/gp/product/B08M6F57PN

Yeah, could be worth a try. A few turners from SWT all bought a cheap unit and had issues with them failing, not working at all etc. But if they have good reviews you might be ok. The Dylos is a little pricey, but the few people I know with them have had good luck. I'd agree you dont need lab accuracy, but something that spews wrong info or dies after 2 months is worse than not having one at all. I bought my Dylos unit in Feb 2018. It's on just about every day and gives repeatable numbers. Hopefully others can recommend other brands?

 

[Russ Braun]

Yeah, could be worth a try. A few turners from SWT all bought a cheap unit and had issues with them failing, not working at all etc. But if they have good reviews you might be ok. The Dylos is a little pricey, but the few people I know with them have had good luck. I'd agree you dont need lab accuracy, but something that spews wrong info or dies after 2 months is worse than not having one at all. I bought my Dylos unit in Feb 2018. It's on just about every day and gives repeatable numbers. Hopefully others can recommend other brands?

I’ve noticed my partial counter collecting a lot of dust on the shelf! When you have an area dust filter device, it is important to turn it on. I find myself doing a cut here and a cut there, never turning it on for those!

 

[Mark Jundanian]

I'm already running a 3HP dust collector and a powered overhead air filter (and I wear a PAPR). I don't know what else I could do even if I had a meter?

 

[Daniel Henry]

I have a dust collector that I use when sanding or turning very dry wood, but it doesn't get everything, and I still find that over time, a layer of dust appears over most of the shop. I suspect an air cleaner would help.

I discovered this Corsi-Rosenthal box design:

View: https://www.youtube.com/watch?v=hIuH-2naozI


It's basically a box make of furnace filters and a box fan. It was designed for COVID-related household air cleaning. I'm wondering if anyone has tried this for shop air cleaning. Any thoughts on whether typical furnace filters would be appropriate for wood dust? If not, what would you suggest?

Thanks!

A scrap piece of 1/2" plywood and scrap 2 x 2 x 21" screwed together; a 12 x 12" hole in the plywood bottom; a 20 inch box fan and filters taped in place. It definitely captures the dust. It is suspended from above by jack chains.

 

[Steve Bonny]

I'm already running a 3HP dust collector and a powered overhead air filter (and I wear a PAPR). I don't know what else I could do even if I had a meter?

Yeah, it depends what you have for components. I have a similar setup to you but you can learn things that might surprise you.
If you are using bag filters or cartridge filters on the dust collector, depending on the type and quality, you'll find they disperse fine dust (the stuff you can't see) all over the shop as soon as you turn them on. Mine take about a week of use to build up a good effective filter layer after cleaning.
It will also tell you if you have a leak in the collection bag or bucket seal.
It will tell you how effective your air filter is too. I have 2 jet units and on high power they take about 15mins to clear my shop after a dust bomb goes off!!
The filters people are talking about building themselves are only as good as the filter elements that they use and how much air flow they get. How do you know it is working? Typical cheap HVAC pleated filters wont filter out the dangerous fine dust. The jet units have a second high efficiency filter bag behind the pleated filter.
It will tell you when it's safe to take off your PAPR too. Sometimes I generate dust at a faster rate than my system can control.

One I never thought about was cleaning up with a shop vac. Even with a hepa filter, it generates more airborne dust than most tools in my shop!

 

[GRJensen]

I'm already running a 3HP dust collector and a powered overhead air filter (and I wear a PAPR). I don't know what else I could do even if I had a meter?

I have a meter ... don't use it much ... it just gives me something else to worry about! Seriously, I have (and use) a 5hp dust collector and overhead air filtration system plus I wear either a dust mask or my Trend Airshield.

 

[Dave Fritz]

We have this in our home since both my wife and I suffer from asthma. https://temtopus.com/products/temto...aldehyde-tvoc-pm2-5-monitor-air-quality-meter I've taken it to the shop and watched carefully the PM 2.5 reading change considerably. Interesting to see how the numbers change when you turn on the filters and dust collector. It stirs up the dust in the shop and blows it around. Like Gerald, I wear a mask all the time I'm in the shop and only take it off when I'm putting on my 3M Air Flow helmet. When you've already worn out parts, it doesn't take much to finish breaking it.

 

[Bob Sheppard]

I have a dust collector that I use when sanding or turning very dry wood, but it doesn't get everything, and I still find that over time, a layer of dust appears over most of the shop. I suspect an air cleaner would help.

I discovered this Corsi-Rosenthal box design:

View: https://www.youtube.com/watch?v=hIuH-2naozI


It's basically a box make of furnace filters and a box fan. It was designed for COVID-related household air cleaning. I'm wondering if anyone has tried this for shop air cleaning. Any thoughts on whether typical furnace filters would be appropriate for wood dust? If not, what would you suggest?

Thanks!

This is a pretty good solution and easy to make. A friend built one and says it's very effective.

Dust Collection Research - Air Cleaner

This site is all about dust collection and protection. It shares the risks from fine dust exposure, how to measure your risks and how to effectively protect yourself and those close to you from airborne dust hazards. Fine dust is so extensively studied that researchers call it PM short for...

billpentz.com

 

[Paul Pyzyna]

I have a dust collector that I use when sanding or turning very dry wood, but it doesn't get everything, and I still find that over time, a layer of dust appears over most of the shop. I suspect an air cleaner would help.

I discovered this Corsi-Rosenthal box design:

View: https://www.youtube.com/watch?v=hIuH-2naozI


It's basically a box make of furnace filters and a box fan. It was designed for COVID-related household air cleaning. I'm wondering if anyone has tried this for shop air cleaning. Any thoughts on whether typical furnace filters would be appropriate for wood dust? If not, what would you suggest?

Thanks!

this would work for a while . When the filters get filled with dust does one replace the filter/rebuild the unit? Also i am concerned about the load put on the fan motor . It is not designed to have more load the just moving air unrestrained.

 

[Michael Nathal]

In 2021 I started a thread on "Dust Collection New Idea"
Here is a copy of the first post. I confess I have only read the article and not put it into practice.

I came across this article the other day: “Dust Collection- The Clean Air Myth”
In the article, he describes his basement woodshop. He has a large cyclone dust collector with hoses linked to major equipment, plus a ceiling mounted dust filtration box. Even with all of that, he can wipe a finger along any wall and come up with dust. (This is similar to my situation)
Anyway, after visiting a cigar parlor with no noticeable smoke, he came up with the idea to add an “air purifier.” to run in concert with his existing system. These are small-ish units with a pre-filter, a HEPA filter, plus an activated charcoal filter. He claims this has solved his problem, no more dust residue. He is so happy that he is buying another unit for his first floor.

Read the whole article, I am just summarizing the main points.
https://www.highlandwoodworking.com/woodworking-tips-1605may/dtew/dtew1.html

 

[Mike Haydon]

Attached is a link to an "Air Filter Shootout" that I found informative. Spoiler: The 20" Box Fan and Filter was in the top 3rd of the pack regarding performance.

Air filtration system shootout - which is best?

Which air filtration system is the best? We tested 13.

www.shophacks.com

 

[Stan Pressner]

I have a great 3hp dust collector, but I also run a 4 sided Corsi-Rosenthal with 4 20x30 Mirv14 filters with a box fan. Easy to build and replace filters, and it works great.

 

[Dan Olsen]

I'll just chime in on this also. The most critical part of the filtering system is the "filter". The PM 2.5 particles are the most dangerous ones to your health and they well may be the ones still floating around your shop even after being "filtered" by your dust collection system. Most of the time, you really can't "see" the PM 2.5 particles because they're so small and also have the best ability to "float" in the air whereas the larger particles fall out easier.
I started with a 3HP Delta "dust collector" which I bought used and it sat on the top of a 55-gallon drum. It was probably more of a "dust re-distributor" than collector as it had no filter, basically collecting the "sawdust" from my tools. I ended up modifying it by adding a Oneida Cyclone to separate the sawdust and then added a large filter bag (! 8' high and 24" diameter) from American Filter Fabric. The company designs industrial bag houses and they'll also help you calculate how much bag surface area you'll need for the Cubic Feet per Minute (CFM) of your "fan". They have lots of bag fabric options depending upon what size particles you're filtering out. My system actually filters both the "sawdust" (via Cyclone which drops into a 30 gallon garbage can) and then the filter bags captures the finer dust in the inside of the bag which then will slough off that dust which drops into a 5-gallon bucket on the bottom of the filter bag.

If your dust collector is operating and you can still see dust in your shop, you can pretty much guarantee that the PM 2.5 particles are hiding in that dust and in you lungs. Adding a face mounted dust mask/filtering system will be the suspenders to add to your belt.