# ventilated floor for dust collection?



## skogie1 (Sep 1, 2014)

In the next year or two I will have the opportunity to build my dream shop. One idea I've been toying with is perforating some areas of the floor and drawing air through them for dust collection. Basically, I'm trying to achieve a downdraft for dust collection in an attempt to keep it funneling down and away from my breathing. I'll of course have the usual hookups for the machines, but as a method to rid the air of floating dust this seems promising. I haven't worked out any of the details yet. Anyone have any thoughts on this idea, positive or negative? Ever see it done or tried it yourself? Thanks in advance.


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## cabmaker (Sep 16, 2010)

I have not seen that done….Seems that that arrangement may create a vortex that you would be in the middle of

I also don't see any reason to not use a nice cyclone system that already exists

By the same token however,,,,,thinking outside the box is what made this country great,,, I say go for it !


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## Redoak49 (Dec 15, 2012)

I think it would take a lot of cfm to do this. Better to get the dust at the source.


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## RandyinFlorida (Sep 27, 2012)

I'm intrigued. I don't think you would need all that much cfm. You are not trying to suck up (down) all the sawdust; just the fine particulates.


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## LittleShaver (Sep 14, 2016)

Sounds fascinating. I'm picturing a floor of pegboard. Would need lots of support, but it sounds interesting. I would have to have lift out panels for recovering dropped fasteners.


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## dhazelton (Feb 11, 2012)

I think of my hot air furnace's filter - if the furnace is on while I scoop a cat litter box I can see a cloud of fine dust headed for the intake and know that it's headed that way - when I change filters it proves the point.

SO - I think if you do this just with normal HVAC ductwork and use a furnace blower motor with squirrel cage fan you can make it work just fine, and I think it would clean the air really fast. But you'll have to change or clean the filters often.


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## eflanders (May 2, 2013)

I agree that it is an idea worthy of further research. IMO It would mean changing your normal air ventilation HVAC system and ducting them through the walls with filteration. Your electrical use would likely go up a lot though as you would want the system to circulate air every minute you are working and then some. If the circulation fans were hooked to a 12 volt solar generator though… A perforated floor wouldn't be needed if you used wall ducts similar to your current fresh air intake vents in your home. Check this idea out with some HVAC folks that also do woodworking and see what they think.


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## bndawgs (Oct 21, 2016)

I feel like this would be the same principle as an air hockey table, except that the fan is blowing in reverse.


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## jamsomito (Mar 26, 2017)

I'm in the energy efficiency industry and I'm picturing something like a data center air conditioning system (only in reverse):










I'm assuming you're just going to hook up a blower to a plenum-type space underneath the floor, like a crawlspace-like area. Plenums work great for return air (and sometimes even supply air), but it's such a huge area, velocities are very low, and it reduces exponentially, radially from the source of suction. I'd worry if you're making piles of sawdust on the floor (like me) eventually you're going to plug that area up and reduce your flow, but maybe not. You'll want to make sure that space is sealed really well too so you're not just infiltrating outside air through the wall boards and losing negative pressure to draw from your space.

I'm also assuming you're just exhausting that air straight outside. To make it work well, you'll also have to consider your make-up air. If you're pulling out 1000 cfm from a makeshift furnace blower setup, you'll be pulling from cracks in the doors, windows, and siding which are all about head-height or lower, so it might not give you the draft you want. I'd put a dedicated make-up louver in the ceiling or high up on the wall to give the air an easy path right where you want it.

Keep in mind though that with the fine dust blowing off the power tools at hundreds of miles an hour, it'll get all over the room fairly well mixed anyway, and this system won't be much more effective than a circulating air scrubber most of us hang from the ceiling. You'll still want to wear a respirator methinks.

These are just some thoughts off the cuff. It's an interesting idea - definitely let us know what you decide and if yes, how it works!


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## TheFridge (May 1, 2014)

I'd focus on superior collection at each point instead of so-so throughout.


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## shipwright (Sep 27, 2010)

I run my big DC piping under my floor and branch pipes come to holes where my machines are located. I don't get much fine dust from machines when the DC is on and when I sweep up I just open a few of the floor holes and turn the DC on. You can actually see the dust rising from my sweeping drift toward the nearest opening. It never rises up to my height.
You might understand my system better if you look at this blog. http://lumberjocks.com/shipwright/blog/series/5536
Segments two and three will show you the most.


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## jimintx (Jan 23, 2014)

Given ever-increasing amathophobia, will the next solution be to install massive exhaust fans, and push so much air through the shop space that it's a bit like working in a wind tunnel?

Why wouldn't a wall of high volume, high velocity exhaust fans be as good or better than some sort of under-floor system?


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## jonah (May 15, 2009)

Focus on superior source collection at the tools. Combine that with a downdraft table for sanding and routing. Those are two operations that create a lot of fine dust. You don't need a downdraft throughout the shop.


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## AZWoody (Jan 18, 2015)

> Given ever-increasing amathophobia, will the next solution be to install massive exhaust fans, and push so much air through the shop space that it s a bit like working in a wind tunnel?
> 
> Why wouldn t a wall of high volume, high velocity exhaust fans be as good or better than some sort of under-floor system?
> 
> - jimintx


Why is it a phobia of dust? Do you believe that fine dust from wood has no adverse health effects on the human body?


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## skogie1 (Sep 1, 2014)

> I run my big DC piping under my floor and branch pipes come to holes where my machines are located. I don't get much fine dust from machines when the DC is on and when I sweep up I just open a few of the floor holes and turn the DC on. You can actually see the dust rising from my sweeping drift toward the nearest opening. It never rises up to my height.
> You might understand my system better if you look at this blog. http://lumberjocks.com/shipwright/blog/series/5536
> Segments two and three will show you the most.
> 
> ...


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## skogie1 (Sep 1, 2014)

Thanks for the replies everyone. Given me food for thought. Just to be clear, I wasn't thinking that this would be my main source of dust collection. I will have dedicated ports at each machine. This was just a thought on how to clear the air of the fine particulates that float around. Thanks again.


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## jimintx (Jan 23, 2014)

I have installed a PM air filter, hung from the ceiling in my 21'x21' space. It seems to do at least a decent job of filtering dust out of the air, and it also can move a lot of air so it serves as a circulating fan while it is running. You could no doubt achieve more dust entrapment with an array of more than one of these style filters.

AZWoody, I do not think the modern and typical usage of the word-ending "phobia" implies the fear has no basis, just that it is a present and stressful fear. One thing clear, is that many who want to work in wood shop environments are also quite concerned about dust in the air. Thus they expend thought, effort and cost to reduce it. I for one have a well ingrained spinning-sawblade-phobia, and that is one I nurture, and know to be warranted.

I am also solidly on the fearful side when it comes to snakes, and there is no way that is not warranted! (However, I am still not really worried about glutens or peanuts.)

..


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## builtinbkyn (Oct 29, 2015)

Will it be recycled air or exhausted to the outside environment? Taking air out of the shop will need to be replaced with air from somewhere else. If recycled, it will need to be scrubbed of particulates. Either way, this will effect your HVAC in the shop and elsewhere in your home if the shop is attached to it. This is probably more complicated solution to an already addressed issue - use a large air filter/dust collector.


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## Firewood (Dec 4, 2013)

I would love to have a shop on a raised floor like those found in data centers. Not for air movement, but for easy access for wiring and ducting. But as jamsomino pointed out, the CFM requirements would be huge to keep even the fine dust moving back to the DC. As an example, CRAH (computer room air handlers) move up to 100,000 CFM to ensure adequate air circulation. Even in a small shop, 1000 CFM would have little effect.


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## JBrow (Nov 18, 2015)

skogie1,

I would think drawing air down through a floor intake would be better that a ceiling mounted air cleaner. Dust generated at the tools would tend downward and away from the breathing zone.

One concern with a downdraft ventilation system could be where the dust is deposited. Dust that is dumped directly under the building, for example in a crawl space, could become a fire hazard over time. Enough dust and moisture would encourage spontaneous combustion. If, on the other hand, the dust is collected by a filter and air returned to the shop or exhausted out of the building, it could be a good system.


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## CaptainKlutz (Apr 23, 2014)

Sounds like you want to build a "clean room"?

Electronics and Semiconductor mfg use clean rooms with laminar air flow top to bottom to keep work areas clean. [versus server farms that use physics of heat movement to push air up]
There are many levels of clean room efficiency and ways achieve cleanliness. Standards and commercial products abound on internet to build these structures. 
Most use typical design: raised floor, porous floor panels, overhead grid where ventilation/filtration units or lighting can be interchanged based on work flow in room. The filtration is handled based on debris size levels. Return air from floor is course filtered via blower cabinets pulling from floor and pushing into overhead plenum, the local downward fine filter units pull from plenum and push it back to floor. Repeat indefinitely.

These types of mfg environments are very elaborate, and costly. Hope you have lots of money. 

Try his companies "How to design clean room page as one example of commercial clean room design. Dr. Google can find you 100 more references if you want more.

Please let us know how you build it. Would love to see my work environment applied to a wood shop.


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## Loren (May 30, 2008)

I think I would drop a lot of screws into
vents in the floor.


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## CaptainKlutz (Apr 23, 2014)

> I think I would drop a lot of screws into
> vents in the floor.
> 
> - Loren


Hehe
You might think so, but commercial ventilated systems used in electronics mfg have high static pressures and small holes in floor panels. Versions I am familiar with holes are too small for #6 machine screw nuts to fit through. 
But you bring up a good point. 
Hole size needed in floor panels would be issue with trying to use electronics clean room systems. As the regular holes were designed to capture dust/lint, and not plane shavings or router chips. 
I know systems with larger holes exist, but they are more like a grate, and typically used in facility with large chemical tanks for plating or etching of electronics to ensure wash down reaches drains. With those "high volume flow" floor systems, you can loose pens/pencils below a raised floor.  Not to mention the chemical scrubbers and dehydration units in those systems to clean the filtered air stream.

Have never seen anyone apply true clean room design to wood working. But there are class 10000 rooms where metal machining happens. Those have special machine requirements with internal filtration to trap debris before it exits machine. 
Which leads us right back to age old wood working challenge, how to trap all dust before it leaves the tool?

Best Luck!


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## theart (Nov 18, 2016)

I toured the Martin Guitar factory about twenty years ago, and remember that they had a room-sized downdraft system at one of the sanding stations. The floor had a pretty wide grating. I think the workers were just hand sanding there, but there was absolutely no dust floating around.


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## Fresch (Feb 21, 2013)

Think about "air box" under each unit, with 1 slot like an upside down vacuum head(funnel). Step on peg rocker opens /close blast gate.


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## BoardButcherer (Feb 21, 2018)

I'd do two things if I followed through with something like this.

First: Don't re-invent the floor. Grab some industrial grade metal grating and put it in and be done with it, even if it costs twice as much. No headaches down the road.

Secondly, don't hook a traditional dust collector up to it. Dust collectors are built for suction, not volume, because we put small pipes on them. Find someone throwing away a large squirrel cage from the renovation or demolition of an old workshop and snatch it up cheap. The key to setting this up is going to be pure airflow volume.

It'd also be wise to make the areas under the floor their own dust traps by tapering them toward one end and putting a sump there. Being able to open up a grate and clean out that sump with a shop vac is going to be a lot easier than trying to keep a bunch of duct work clean. You can even put some cheap vibrators on the pans with a valve to make it easy to shake the dust down to the sump.

However, I'll reiterate what everyone else has been saying: This is a lot of elaborate and expensive chicanery for the sake of a little dust. Just get a mask and put the money in the tools and some extra floor space.


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## ArtMann (Mar 1, 2016)

I believe a certain amount of organic dust in the lungs is harmless. If this weren't true, we would all be dead by now. People talk as if woodworking is the only opportunity they have to ingest dust. That is just silly. I think fanatics like Bill Pentz have raised the problem of wood dust to the hysteria level. Everybody knows that dust collection is important. It is a matter of how much. I would be more concerned about inorganic material like silicon that the body can't absorb and expel.



> Why is it a phobia of dust? Do you believe that fine dust from wood has no adverse health effects on the human body?
> 
> - AZWoody


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## Finn (May 26, 2010)

As a retired HVAC guy that has worked in a lot of clean rooms and rooms for mainframe computers ,Captian Klutz has hit the nail on the head. It will work very well and will require a lot of CFM.


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## MrRon (Jul 9, 2009)

Before I retired, I did design work on clean rooms for the U.S. Naval rework facility. They were able to keep the particulates inside the clean room down to around 3 ppm (parts per million). They would work on hydraulic cylinders used on fighter jets. No dust was permitted when working on hydraulics. Naturally a large amount of air had to be circulated. The room was under a positive pressure. Cost was obviously very large. To be effective, it has to be a closed system. I'm not suggesting a wood shop has to be built like a clean room.That would certainly be impractical; even commercial woodworking facilities don't use it.


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## Andybb (Sep 30, 2016)

As someone else said, I'd be worried that every small nut, bolt and screw that I dropped would fall through the holes. I think you'd still have a fine layer of dust on the floor. Sure sounds like a good idea, though a lot of work for what might be minimal improvement. Normal cyclone type extraction and a few well placed ceiling filters might be more efficient.


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## CARSandCustoms (Jul 26, 2018)

I know this is an old post, but just wondering if anyone has thought about automotive (or truck) paint booths for heavy dust control?

I have spent most my life in collision/restoration and have used many paint booths and prep stations. Both remove particulates by passing through a bank of filters, either on a wall (side-draft) or through the floor (down-draft). Paint fumes need to be exhausted outside, but in prep station configurations, they can be recirculated back into the shop.

Used booths are cheep or free when they are removed from closing or remodeled body shops depending on the features included (heated make-up air furnace, pressure controls, etc.)


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## runswithscissors (Nov 8, 2012)

Reminds me of a TV commercial is just saw. A lady (happily smiling, gleeful even) is spraying some sort of air "freshener" around her living room. What is that crap, and why do we tolerate it in our living space? Surely it isn't a benign material? It has been well documented that many substances that are ubiquitous in our modern environment mimic estrogens, and that is generally not regarded as a good thing.

And what does Martha Stewart have to say about it?


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