# Powermatic pm1250 vs. homemade



## islandbum561 (Nov 27, 2020)

I've never had a filtration system in my shop before but I think it's time to step up. With that said I'm curious. It seems that these systems are not much more than a fan with a filter but maybe I'm missing something. Not trying to be cheap but I don't like to waste money either. Any thoughts? 
If I were to buy a quality unit I have been looking at the Powermatic PM1250. 
Any help/advice is appreciated.


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## difalkner (Nov 27, 2011)

Welcome to the forum! I built my own with a 20" box fan and a filter - about $30 total investment. I turn it on low every morning and it runs all day. If I happen to be creating dust then I turn it on high for a while.
















David


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## Dave McCann (Jun 21, 2020)

islandbum561 said:


> It seems that these systems are not much more than a fan with a filter but maybe I'm missing something.


As long as you have the expertise to put together an ionizer system to charge the electrostatic filter and build and airtight housing with efficient airflow, you can build one that equals the PM type units.

On the other hand many folks have used a simple furnace filter and a box fan.

Any filtration system is going to better than none but I doubt all systems are equal.


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## difalkner (Nov 27, 2011)

Even though I catch most of the dust at each source I still end up having to clean the filter, so I know it's working. I just pull it down and use the shop vac to clean it, probably replace the filter once each year.

David


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## Dave McCann (Jun 21, 2020)

difalkner said:


> Even though I catch most of the dust at each source I still end up having to clean the filter, so I know it's working. I just pull it down and use the shop vac to clean it, probably replace the filter once each year.
> 
> David


"working" is relative. Any filtration is better than none. What is important is how many micro particles are getting thru the filtration used, and being breathed into one's lungs.


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## Tool Agnostic (Aug 13, 2017)

Whatever filter you have, I would wear a dust mask, too.

I work mostly outdoors. I always wear a dust mask, whether I am working outdoors or indoors. Consider it "defense in depth."


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## HoytC (Dec 30, 2019)

The PM1250 is, AFIK, the only hobbyist air cleaner with testing to the AHAM spec (the industry standard for air cleaners). The details are on page 5 in the manual. Specifically, the dust CADR is listed as >400 CFM. (CADR can be interpreted as being approximately Fan CFM times filter efficiency.)

I've tested a boxfan with a MERV 12 filter and it does _roughly_ 160 CFM CADR for particles between 1.0 and 10 micron. For 0.3 to 1.0 micron the approximate CADR is 140 CFM. So two or three fans like David shows might approach the performance of the PM1250.


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