Replies

1. 
   KiddervilleAcres | Mar 11, 2008 03:45am | #1

   If you are talking about the overhead air filters I have one in my small 16' x 20' woodshop.  The roofline is gambrel shaped as is the ceiling in the woodshop.  When I plan on using dust generators I start the air filter when I go into the shop.  It takes about 10 mins. but by then it will be circulating the air throughout the woodshop.

   I also have a DC and all I can tell you is that I have to clean the overhead filter about every 3 months, so it's doing something!  Another benefit is that it also circulates the heat and keeps things dry. 

   I heat my woodshop (only when I'm using it in the colder months) with a house trailer furnace so I can relate to you and your woodstove.  I used one B4 but lugging wood up to the second floor was a PITA.   And it was always a mess on the floor.  The furnace, with the thermostat keeps the woodshop nice and an even warm heat.  Cost is just about the same, at least here in NH. 

   Just my 2¢,

   Bob @ Kidderville Acres

   A Woodworkers mind should be the sharpest tool in the shop!

1. 
   Brucemc | Mar 11, 2008 04:16am | #2

   Bob,  thanks for the prompt reply.  We seem to have the same shop size.  What make is yours?  Does your filter get ride of most of the fine particles of dust that land on everything only to be discovered the next time you go into your shop?  I'm in Ontario where it started to snow in November and two days ago we got another foot and half!  Cheers

1. 
   KiddervilleAcres | Mar 11, 2008 04:28am | #3

   Hi Bruce,

   Mine is a Pioneer sold by Western Tool as their name brand.  I've been told that it is the same as a JDS but not sure how accurate that is.  It does a good job for the most part 'cause every once in a while I make a cut without turning it on and every time I have the dust film everywere.  So I'd say yes it does work.  Still put on the dust mask as well though.

   Also, the breathing is a whole lot better.  I did install both the DC and the air filter at the same time so I'm sure both contributed.  If you're hesitant to purchase one I wouldn't give it a second thought, go for it.

   It's quickly becoming a habit to just turn it on when I go into the woodshop no matter what I'm going to do.  Good habit to get into I think.  Can't wait to see how it works in summer when it can get a bit hot up there!  OPen the winders and the door and let her rip!

   Oh, and that 1½' of snow you got was rain here.  Now it's all froze up again but is supposed to warm up as the week goes on.  C'mon spring/summer!

   Regards,Bob @ Kidderville Acres

   A Woodworkers mind should be the sharpest tool in the shop!

2. 
   forestgirl | Mar 11, 2008 08:08am | #4

   My shop is 22' x 22' with mostly an 8' ceiling, though it goes higher on one end.  I bought a JDS filter, the absolute best-rated filter at that time, and it makes a noticeable difference in the air quality.  I would encourage you to go with a known brand. 

   forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 
   
3. 
   wilburpan | Mar 11, 2008 07:34pm | #5

   As you've found, although the best way to deal with dust is to collect it at the source, from a practical standpoint, that's very hard to do even with the best cyclone systems. Therefore, you'll need a backup plan to deal with the dust that your dust collector misses, which is where the air cleaner comes in.

   Conventional wisdom says to get an air cleaner that will circulate the volume of air in your shop 6-10 times an hour. I went for 25-30 exchanges per hour in my workshop, which will bring down the ambient dust much more quickly. To save you some math, the JDS 750-ER, which is what I have, will meet this goal in my 11'x20'x8' shop. If your shop is 20' x 20', getting two of them will achieve this.

1. 
   KiddervilleAcres | Mar 11, 2008 07:45pm | #6

   Why the need to triple the circulation rate?  Does the JSD filter smaller particulates than your DC, i.e. .5 micron vs 1 micron?

   Just curious,Bob @ Kidderville Acres

   A Woodworkers mind should be the sharpest tool in the shop!

1. 
   wilburpan | Mar 11, 2008 08:22pm | #9

   Hi Bob,The JDS has a 1 micron filter, but that's not why I wanted to go up on the circulation rate.The more times that the air cleaner can circulate the air, the quicker the ambient dust will get filtered. I made some assumptions: that for each pass of air, 75% of the dust actually gets trapped. (I know that the manufacturers claim otherwise, but I wanted to be conservative here.) With the help of some of the forum posters here in the past, i was able to figure out the math to see how quickly the dust would drop.So after cycling the room volume of air once, 75% of the dust would get trapped. The actual percentage is a bit lower, because of ongoing mixing during the filtering. The next pass, 75% of the 25+% of remaining dust gets filtered, and so on.If you work through the math, at the usual 6 air exchanges per hour, it takes 2 hours and 10 minutes to reduce the dust to less than 1% of the original level.If you shoot for 25 or so air exchanges per hour (which isn't hard: my 11'x20' shop has 1760 cubic feet, my air cleaner is rated at 750 CFM, which works out to 25 exchanges per hour), it takes 16.4 minutes to reduce the dust to less than 1% of the original level.16.4 minutes of dust in the air vs. 2 hours and 10 minutes. Kind of a no-brainer to me.That's why I've become a big fan of air cleaners. It's ridiculously easy to upgrade your air cleaning capacity -- just add more air cleaners. 20'x20' shop? Buy two air cleaners with 750 CFM each. Compare that to upgrading from a 1.5 HP bag dust collector to a cyclone system. Air cleaners are also relatively inexpensive, which makes doing this pretty cost-effective.Again, the best solution would be to trap all the dust at the source, but that's very difficult to do, so you need a back up plan.Wilbur

1. 
   KiddervilleAcres | Mar 11, 2008 08:44pm | #11

   Wilbur,

   Awesome! 

   Thanks for the explanation; make sense.  I was concerned with both filters having the same capture ability in terms of particulate size that air filter would have little effectiveness.  But, as the air filter does its work particles collect on the filter media thus capturing smaller particles over time I would suspect.

   What really piqued my interest was the dramatic reduction in the time of effectiveness if you will, 16.4 minutes vs 2 hrs. 10 mins!  After your explanation I wonder, if the air filter could capture finer dust would it further reduce the time?

   Thanks again,Bob @ Kidderville Acres

   A Woodworkers mind should be the sharpest tool in the shop!

1. 
   wilburpan | Mar 11, 2008 11:44pm | #13

   Hi Bob,I'm not sure about that. It seems to me that as a filter becomes caked, it may improve efficiency, but it probably won't capture that many particles below its rating. After all, if a 1 micron filter can capture 0.5 micron particles after caking, every manufacturer in the world would claim 0.5 micron filtering ability, no? :@)I think that the major factor as to how quickly an air cleaner can remove dust from the air is how much air volume it can process in a given amount of time.Wilbur

   Edited 3/11/2008 4:45 pm ET by wilburpan

2. 
   saschafer | Mar 11, 2008 11:48pm | #14

   It's a trade-off between filtering efficiency and airflow efficiency. A 1000 cfm system whose 1.0 µm filter is caked enough to filter 0.5 µm particles is no longer a 1000 cfm system. ;-)

   -Steve

    

3. 
   wilburpan | Mar 11, 2008 11:57pm | #15

   They would probably claim both.Just like the specs you see on dust collectors."950 CFM! 8" of static pressure! All on only a 1 HP motor!!!":@)WIlbur

2. 
   Brucemc | Mar 11, 2008 07:56pm | #7

   I am not familiar with the JDS line.  Delta, King, General and Jet are the main lines our we have access to.  I will check into availabiltiy in Canada.  Thank you for your advice.  Much appreciated.

1. 
   wilburpan | Mar 11, 2008 08:26pm | #10

   You don't need JDS specifically. What you need is:-- a 1 micron filter in the air cleaner
   -- 1100 CFM. THe JDS is rated at 750 CFM, but they rate their air cleaners conservatively, and most other manufacturers equivalent is 1100 CFM. I know that General, Jet and Delta all make units that fit this description.A remote and timed shutoff is also nice to have.

4. 
   GRW | Mar 11, 2008 07:57pm | #8

   I have a JET with a washable pre-filter. Makes a world of difference. I run it when I'm making dust and for 2 hrs. (it has a 2,4 or 8 hr timer) after I leave. When I return, the air seems dust free.

   Try this.. Do some work in the shop at night. Make some dust. Then turn a flashlight on with the shop lights off. Take a look at the airborne dust particles the flashight highlights... I expect this will help you make up your mind.

1. 
   Brucemc | Mar 11, 2008 11:18pm | #12

   The sun streaming into the shop this afternoon confirmed what your experiment at night would have.  I immediately put on my dust mask and opened some windows.  Thanks for taking the time to respond.  Cheers

5. 
   tuolumne7 | Mar 12, 2008 01:22am | #16

   I am very pleased with the performance of my JDS...I've had it for nearly 2 years now.  With my new dust collector set up in the shop at the house we're building I hope to generate much less airborn dust to begin with!

1. 
   frankv | Mar 12, 2008 05:35am | #17

   There was an article sometime back in FWW on building an air filter box along the same lines as a JDS. I followed that design and ordered an industrial axial fan from Grainger (665 CFM, model no. 3VU71, $65) and built a box out of plywood to accommodate the fan at one end and space for (2) filters at the other end with a hinged door and foam seal. Works great since filtering dust is not rocket science - you just need to get some really good filters such as the ones used as replacements for the store bought filter boxes (and a good fan). We woodworkers can build the box in no time.
   I put a pull switch on mine but the original design had a timer so that when you leave the shop the fan runs for set period of time. No need to get that fancy but simple to do if you want to.
   My 2 cents.
   Frank

1. 
   RonInOttawa | Mar 12, 2008 04:42pm | #18

   If you are interested in building your own, check with one of the heating/AC companies where you live. Every time they change out a furnace (average 20 years old) they also change the blower unit. These units usually use a squirrelcage blower driven by a 1/8th to 1/4HP motor. The blower is usually rated for at least 100,000 hours of operation and has rarely received half that in normal service. Most places will give you these units for nothing, as they are usually just put in a dumpster. The last time I picked one up the guy told me that it would be no charge, but I had to take TWO units! Cleaned up the blower, cleaned and oiled the motor, installed a link belt and it was off to the races. That part of me that has a Scot heritage was proud!My unit uses a standard furnace filter backed by 2 3M filters that catch stuff down to 1 micron. I don't remember the FWW article I used as a reference, but I do remember it was based upon a design by a gentleman whose last name was Kornfield. I've hung it from the ceiling in the center of my shop and I'm pleased with the performance.Regards,Ron

1. 
   frankv | Mar 12, 2008 07:04pm | #19

   Recycling an old furnace blower is a great idea!
   The next time I upgrade I will do just that. I have a neighbor who installs furnaces so I will ask him. My homemade filter is sized right for my small shop but when I expand I will need to build a larger one.
   Thanks.
   Regards,
   Frank

2. 
   Brucemc | Mar 15, 2008 02:13am | #20

   I remember the article now that you mention it.  Many thanks for your reminder and the response.  Cheers