Dust Collection Air Filter

[SpiderDave]

I'm another guy putting together a 2 stage dust collection on the smallest budget possible. It's proven to be a more difficult than I expected. I've done tons of reading, searches and can't seem to get past the filter issue. Maybe someone could offer testimonials or advice on how they ended up doing theirs?

So far I'm heading down the Harbor Freight DC route with a DIY Thein separator. But after reading up, I can't come to terms on the air quality issue. 

I'm thinking I would like to have an optional bypass for outside venting for the ultra fine stuff, during warmer seasons. And in winter I'd like to recirculate it to save my heat. Tell me if I'm wrong here, but it seems there is no real answer to getting all the dust to safe levels, unless you exhaust the fine particles outside. I have an area that would do well for that, and it wouldn't bother anyone. But it's not a good option if it builds up and kills vegetation in the surrounding area later, or even years down the road for that matter. (from what I've read)

I do have mild asthma, which I'm not tippy toeing around, but it is something I have to think about as it can hit me occasionally. So, I read that even 0.05 microns is bad for you over time. The more I read, the finer and more expensive filter I start looking for. Seems like a vicious cycle. Having an air scrubber or high end filter isn't financially practical for me a this time. I do have a DIY filter hanging up that's on when I'm out there to grab what I stir up in the air - best it can. But that's not anything I want to rely on. There are nice higher rated bag filters out there. I like the idea of a washable or paper louvered filter with lots of filter surface area. But what I found was around $200 for the filter. Is that good? I don't recall the rating.

So, in a nut shell. If I pipe it outside during warm seasons, is there no avoiding toxic build up against vegetation? Or is that even true? And when I recirculate the air inside my shop during the colder seasons. What's the best method or product to get that air clean and not have to think about the fine powder floating about?  I'm open buying a different system if it's not too far out of range. But it's mostly about the air filter and what, where or how? If anyone has a better idea, I'd love to hear it.  Worse case scenario I have a baffle at the end after 2nd stage where it can either pipe air outside or recirculate inside and it can be filtered either way and problem solved. But I'm not sure that's necessary, is it? Never thought a dust collector would be so complicated. Ha! Thanks for reading.

[photobug]

I'm another guy putting together a 2 stage dust collection on the smallest budget possible. It's proven to be a more difficult than I expected. I've done tons of reading, searches and can't seem to get past the filter issue. Maybe someone could offer testimonials or advice on how they ended up doing theirs?

So far I'm heading down the Harbor Freight DC route with a DIY Thein separator. But after reading up, I can't come to terms on the air quality issue. 

I'm thinking I would like to have an optional bypass for outside venting for the ultra fine stuff, during warmer seasons. And in winter I'd like to recirculate it to save my heat. Tell me if I'm wrong here, but it seems there is no real answer to getting all the dust to safe levels, unless you exhaust the fine particles outside. I have an area that would do well for that, and it wouldn't bother anyone. But it's not a good option if it builds up and kills vegetation in the surrounding area later, or even years down the road for that matter. (from what I've read)

I do have mild asthma, which I'm not tippy toeing around, but it is something I have to think about as it can hit me occasionally. So, I read that even 0.05 microns is bad for you over time. The more I read, the finer and more expensive filter I start looking for. Seems like a vicious cycle. Having an air scrubber or high end filter isn't financially practical for me a this time. I do have a DIY filter hanging up that's on when I'm out there to grab what I stir up in the air - best it can. But that's not anything I want to rely on. There are nice higher rated bag filters out there. I like the idea of a washable or paper louvered filter with lots of filter surface area. But what I found was around $200 for the filter. Is that good? I don't recall the rating.

So, in a nut shell. If I pipe it outside during warm seasons, is there no avoiding toxic build up against vegetation? Or is that even true? And when I recirculate the air inside my shop during the colder seasons. What's the best method or product to get that air clean and not have to think about the fine powder floating about?  I'm open buying a different system if it's not too far out of range. But it's mostly about the air filter and what, where or how? If anyone has a better idea, I'd love to hear it.  Worse case scenario I have a baffle at the end after 2nd stage where it can either pipe air outside or recirculate inside and it can be filtered either way and problem solved. But I'm not sure that's necessary, is it? Never thought a dust collector would be so complicated. Ha! Thanks for reading.

Sounds like you have it pretty well figured out.

A wynn filter will handle the bad dust issues yes it's around $200.  This is based on enough suction going to the tools to remove most of the dust coming from the machine.  The issue with the Thien Baffle it only works so well and it will tax the Wynn filter more than a high end separator.  

I have my collector only set up for a few weeks and with 6" duct and a Dust Deputy separator there is very little dust even getting past that stage so little to end up in the filter to clean or out to poison the plants.  The rest of my pipe and tubing arrive this week so will have a better feel for the entire setup once I got all my tools attached.  I thought once the collector was installed the hard part was done.  Getting all the ducting installed and attached to the machines is proving an even bigger pain, and the bits and pieces are really adding up.

[SpiderDave]

Sounds like you have it pretty well figured out.

A wynn filter will handle the bad dust issues yes it's around $200.  This is based on enough suction going to the tools to remove most of the dust coming from the machine.  The issue with the Thien Baffle it only works so well and it will tax the Wynn filter more than a high end separator.  

I have my collector only set up for a few weeks and with 6" duct and a Dust Deputy separator there is very little dust even getting past that stage so little to end up in the filter to clean or out to poison the plants.  The rest of my pipe and tubing arrive this week so will have a better feel for the entire setup once I got all my tools attached.  I thought once the collector was installed the hard part was done.  Getting all the ducting installed and attached to the machines is proving an even bigger pain, and the bits and pieces are really adding up.

Well, thanks. But every time I 'think' I have it figured out. I read something else that creates doubts and I feel like I need to research even more, and it starts all over again. I chose the Thein separator because it was an easy build, low budget and it seemed really effective for most people. Cyclones seem great too. I'm still trying to get my head around the requirements to run it and which is more effective. I haven't been able to get into as much debth with that one. Or to find a cross section diagram to better understand what a cyclone does, but still trying. When you mentioned 'a high end separator' is that something that would work better? I'd be interested in knowing what that might be, if you can get me on a better path? If anything, just to learn. I'm always open to new options, especially as it's still on the drawing board.

[WilliamHodge]

Literature about dust collection venting outside doesn't account for having multiple sized systems in a one person shop. Using only the dust collection you need cuts down on wasted air flow. Talk to a person that has done it.

I vent an 11' blower and a 6" blower into a trailer. The trailer has a 4' x 8' x 4' tall box on it.  When it's full, a farmer takes it away for animal bedding.I have a shop vac on a barrel cyclone for fine dust, sanders, router, the hose on the rip saw feeder, and cleaning the floor. Brooms are bad for dust.

Such a system requires make up air. I crack a window at the other end of the shop when I use the big blower.

There isn't that much dust that lands outside. I keep the grass long. shovel up the spillage occasionally so that ants don't move in. The fine dust, in the 55 gallon drum cyclone, gets composted on the edge of the woods. The  sawdust on the ground ends up rotting in the meadow behind the shop. Tree roots have extended into the area, and feed on the rotting wood. Native grasses meadow plants are doing well.

The shop gets down to 50-55 when I mill in the winter. It's worth it for clean air. I heat with propane to water radiant in the floor, and electric oil filled heaters with photo voltaic panels. Air sealing the attic, and insulating with 10" in the walls and 20" in the attic helped a lot. The constant heat loss to a poor building envelope is worse than intermittent dust collector loss.

If you filter air, it should be filtered well enough to fill scuba tanks. I'm not that good an industrial engineert.

[TDKPE]

The shop gets down to 50-55 when I mill in the winter. It's worth it for clean air. 

I had a stack of truck air filters I'd never put into service for final filtration, as when I first built the cyclone I just piped it out a window.  I've never bothered to change it.  Blowing what little dust gets past the cyclone, and it really is very little, just doesn't bother me.  Or my neighbor.  It doesn't leave residue in the snow in the window well, but there's fine wood flour in the bin under the cyclone.

As to the heat loss, I like it cool.  The shop is in the basement, with a second window for makeup air so it's not pulling heat out of the rest of the house other than what it eventually takes to bring it back to the low 60's where it tends to be, and I don't run the DC that much anyway.  

Works for me, anyway.  And I like the clean air.  

[fredhargis]

Venting outside is a great way to expel any fines, and the loss of conditioned air is the only concern I would have. You won't hurt the plants, but if you live in a tight neighborhood you might irritate some of the neighbors. There are photos on the Clear View forum of guys who built a diverter, it allows venting outside in the summer and use the filters in cold weather. Bear in mind that even a world class DC system will not get all the dust in your shop. There will be many operations where the DC isn't in play, as with hand held power tools, and there are some larger power tools that just seem to defy DC (like a miter saw). So I have 2 suggestions, the first would be to consider have an ambient air cleaner. A shop built one works great with the proper filters. While it's true that by the time the dust reaches the filter it's already in your lungs, running one a few hours awhile your not in there catches dust that would otherwise be lying around waiting for you to stir it up. The second is the filter. $200 for a filter is about right...but there is one available that's a little cheaper. Penn State sells this one for $144 plus shipping, and if you've not visited the website you might see an offer of 10% off on your first order. I bought one of these and replaced the filter on my Oneida DC needed to be replaced. These are American made Clark filters, and have a Merv 15 (IIRC) ratings and lots of filter area. The diameter is a little small for a single stage DC, but it could be made to work with a plywood baffle to sit it on. One of them filtered air so efficiently that my DC (5 HP, 14 1/4" impeller) was not restricted in any way...I have a gauge to measure the back pressure.  Lastly, DC can be as complicated as you want; and opinions vary so widely that you will find advice at times to be contradictory. I wish you luck with your endeavor.

[edmorini]

Not knowing your shop layout or size I would offer the following:
When I considered my DC system I assumed that the DC would be responsible for the heavier waste only and the dust dust would be handled by air cleaners. This accomplished my two objectives of keeping the heated air inside in winter and the dehumidified air in during the summer to maintain a pretty constant moisture content within the shop. In addition I built two 900 cu ft/min air cleaners described in "Woodshop Dust Control" by Sandor Nagyszalanczy. Its been over twenty years and no complaints. After a long day on the shop, the next morning I find little or no fallen fines. I am sure, if I sprang for better bag filters in the cleaners, it could be "operation room clean". I do like the "closed as can be" environment of the shop saves of heat/drying cost, no outside contamination, or changing over the system to interior or exterior mode.

Ed

[SpiderDave]

Thanks ALL! I'm starting to feel better about this now. Those contradictions Fred mentioned were tossing me for a loop, been kinda chasing my tail. I am curious if there's a formula to calculate the size of the Thein or a cyclone to a system? I'm probably going to get that Harbor Frieght DC. Mainly for the blower on a low budget. I need dust collection for a Floor standing spindle sander, 17" Bandsaw, 12" DeWalt 735 Surface planer (with built in blower), scroll saw, and a 6" joiner planer, orbital sander, floor standing belt disc combo, and a floor standing disc sander. You guys will probably laugh at me, but I'm almost considering just having one hose from my dust colleciton ready to connect to whatever I pull out to use. Long story short, I work mostly in the middle of my area and when I need a larger tool I wheel it out from the row of tools, use it and put it back. My space is limited. I'm building walls around this area, enclosing it from the rest of the shop. This area has an 18' steel welding fume extraction adjustable arm that can reach most anywhere over my work area. Also, I also have a general use ventilation fan in the wall of that room too. And a 12' x12' cargo door I crack open sometimes. On the other end of the shop I have the man door rigged with a screen door and furnace filters to help with incoming air. When this is done, I'll have woodworking on one side and metal on the other side. I have a weld curtain that spans the length of the room and to the floor to protect my wood working tool's (and table tops/platforms) from weld splatter and grinding. It works like a charm.

I'd like to run the external exhaust pipe straight across to the opposite side of my shop - less friction with no turns. Probably be around 25'. So, without factoring in the wind etc. Is that far enough away? I'll pipe the darn thing underground and come up far away, if I have to. So with this area pretty well closed off from the rest of the shop, I'm thinking my heat loss will be reduced. Keeps dust out. I do this to keep weld fumes, sparks and grinding dust out as well. My wood and metal collection will be separate. Will this HFreight DC unit even come close to handling this? Here's a good laugh for you guys, I'm considering just using one hose and connecting it to the machine I pull out to use at the time. Would it be more effective dust collection this way? I do have a powerful centrifugal blower/fan I picked up from a roof ventilation system job years ago. A Dayton fan and Dayton motor, belt driven. But I have no idea how strong it is. It is a beast though. Sounds like a jet engine. Has an 8" round intake and a square 4'x6" exhaust. Almost rather use that really but it may be over kill. The Harbor Freight dust collector specs says its 1550 cfm.

Here it is: https://www.harborfreight.com/2-hp-indus...97869.html

Thanks again in advance!

[TDKPE]

Or to find a cross section diagram to better understand what a cyclone does, but still trying.

A cyclone simply forces the air flow into a downward spiral within the body, with the dust flying to the outside of the helical flow pattern as it descends.  As the air gets near the bottom of the cylindrical part, it starts to turn inward toward (and eventually into) the exit tube in the middle, while the dust continues to spiral downward along the walls of the conical bottom section, into the lower tube and on down to the collection bin.  It's a centrifuge for small particles, to separate them from the air.

A well designed cyclone unit will remove almost all of the dust, including very fine dust (wood flour), leaving very little of the finest particles to be captured by the filters or exhausted directly outside.

I'm probably going to get that Harbor Freight DC. Mainly for the blower on a low budget. See photo below.

You guys will probably laugh at me, but I'm almost considering just having one hose from my dust colleciton ready to connect to whatever I pull out to use.  Nothing wrong with that.  Lots of folks do that, especially where space is an issue.  Just use the largest hose you can adapt, and use smooth-walled hose, not the internally corrugated cheap stuff, which presents much more flow resistance than anything smooth.

I'd like to run the external exhaust pipe straight across to the opposite side of my shop - less friction with no turns. Probably be around 25'.  Funny you should say that.  I have 20 ft of 8" dia insulated flex, exhausting out a window.  Insulated mainly because it was very flexible, and very cheap.  It has to be flexible so I can swing the window adapter open sometimes.  See photo below.

Will this HFreight DC unit even come close to handling this? Hard to say.  As fredhargis pointed out, the claimed air flow rate is a fantasy.  I got my '2 hp HFDC' up to around 960 cfm using a 6" test duct with some end treatment (don't remember if it was a flared opening or just a ring), reduced to the 5" inlet, no bags.  Maybe 8 ft of test inlet duct, but no flow straightening vanes.  That was a totally useless arrangement, which couldn't get anywhere near the published performance.  I was drawing 13.9A at 116.4V at the receptacle. 

I do have a powerful centrifugal blower/fan I picked up from a roof ventilation system job years ago. A Dayton fan and Dayton motor, belt driven. But I have no idea how strong it is. It is a beast though. Sounds like a jet engine. Has an 8" round  intake and a square 4'x6" exhaust. Almost rather use that really but it may be over kill. The Harbor Freight dust collector specs says its 1550 cfm.  A blower like that is designed for relatively low static pressure through some large straight duct.  It won't do much trying to pull through a small flex hose to a machine.  Most likely.

I plopped my HFDC on top of my Pentz cyclone, after opening the blower cover's inlet from 5" dia. to 9" dia. (half the cyclone body diameter).  Made a big difference in reducing the losses.  Even with all that exhaust hose, and 6" trunk line along the wall, I can get it to pull around 1000 cfm, based on the increased current draw.  I don't remember what it flows with the largest blast gate open, though I did measure it once.  That blower wheel is tiny, so it can't move much air through a high restriction (max SP was about 7" WG), but opening it up to let it breathe helps move more air than it was designed to.  Gotta watch the current draw, though, as the motor doesn't actually have a nameplate, and I don't know what it's capable of without unduly shortening the insulation life inside.

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Oh, and a ventilation fan is always a good idea.  


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[fredhargis]

Just a comment about that 1550 CFM. Those numbers are less accurate than the 6.5 HP your shop vac has. DCs sometimes measure air flow with no restrictions at all, and that number drops drastically once the blower is hooked to almost anything. My DC is a true 5 HP with a 14.25" impeller and it pulls a measured 1150 CFM through 6" duct ( a little over 550CFM in 4"). The HF is about 1.5 HP with a roughly 10" impeller....so the 1550 is a pipe dream. This isn't a criticism of that DC (maybe the specs) since a lot of folks have it and get satisfactory performance from it, but to compare it to others on the basis of that info is really not realistic.