Replies

1. 
   hammer1 | Jun 21, 2007 06:47am | #1

   Matt, seize the opportunity to build a new, separate shop. Some folks just duct tape a couple of furnace filters to a cheap box fan. If you want to build something more extensive, you can look at Graingers. They have a lot of different blowers. Something like a small centrifugal blower might work.

   http://www.grainger.com/Grainger/categories/hvacr/blowers/small-centrifugal-blowers

   Beat it to fit / Paint it to match

1. 
   kummell | Jun 21, 2007 06:54am | #2

   thanks Hammer - will check out that website...

   we've only been in the current house for a year, but it's already been agreed - next house, separate woodshop!

2. 
   EF | Jun 21, 2007 08:33am | #3

   Get a used squirrel cage blower from an old furnace from a HVAC company.
   Edward

   
   

   ---

   Edited 6/21/2007 1:33 am ET by ef

1. 
   kummell | Jun 21, 2007 03:05pm | #4

   thanks edward - any suggestions on size/cfm?

1. 
   zolton | Jun 21, 2007 03:12pm | #5

   I don't know the design of the blower you're trying to build, but I'd be wary of using a furnace blower to power it. Those are powerful units and they move a lot of air. It seems as though all the air running around would blow the dust around even more.

   I use a cheap ($20.00 new, but I found mine out by the side of the road on trash day) box fan with a square (20x20) furnace filter placed in front of it in a frame. It gently cycles the air in my shop through it. When the filter gets clogged with fine dust, instead of throwing it out I simply vacuum it off. Was there ever a more frugal man? My wife would say no..

   For the low cost of these units you could set up a couple around your shop and still be miles ahead. Mine hangs from the ceiling so it's out of the way, but if you've got more than one you could place the "loose" one around by where you're doing sanding or some other dust-creating activity.

   Zolton 

    

1. 
   forestgirl | Jun 21, 2007 08:40pm | #10

   The "air scrubbers" (filters) made by JDS and other companies move 1000 CFM or more (unrestricted).  Pretty hard to do that with box fans, I'd think, without really cluttering up your shop!forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

2. 
   forestgirl | Jun 21, 2007 08:37pm | #9

   Kummel, sorry it took so long for me to find this old, old thread, but here's "JackieChan"'s detailed post on building an air scrubber.

   http://forums.taunton.com/tp-knots/messages?msg=11626.1

   If you lived closer to me (like west of the Mississippi, LOL) I'd offer to sell you my new Dayton blower that I don't need.  Sorry!

   forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

   Edited 6/21/2007 7:15 pm by forestgirl

1. 
   EF | Jun 21, 2007 10:45pm | #12

   That seems to link to a rust removal thread... but please try again!
   EdwardI found it, I think:
   http://forums.taunton.com/fw-knots/messages?msg=3148.1

   Edited 6/21/2007 7:02 pm ET by ef

1. 
   forestgirl | Jun 22, 2007 02:14am | #18

   Ahhhh, jeeeeeeeeez!  OK, here it is:http://forums.taunton.com/tp-knots/messages?msg=11626.1

   I know what I did wrong, sorry.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

2. 
   kummell | Jun 21, 2007 11:04pm | #13

   fg, thanks for the post, but as edward posted - I'm actually doing quite well keeping rust off my bandsaw blades (helps to not actually have bandsaw blades or a bandsaw!!)

   I'll dig around for JackieChan and see what I can find.

   hope you're doing well!

   Matt

    

1. 
   forestgirl | Jun 22, 2007 02:15am | #19

   ...and for you, Matt.  Sorry!

   http://forums.taunton.com/tp-knots/messages?msg=11626.1forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

3. 
   kummell | Jun 21, 2007 11:43pm | #14

   I think this'll get peeps to the posting you were referring to...

    

   http://forums.taunton.com/tp-knots/messages?msg=11626.1

3. 
   EF | Jun 22, 2007 01:59am | #16

   Take what you can get free or cheap, I replaced my furnace so it was free and I got a used electric air cleaner too. Now if someone would give me a big HEPA filter...
   There are plans on the net for downdraft table/infeed or work table/air cleaner see:
   http://www.fineboxes.com/DowndraftTable.htm
   http://www.woodworkersworkshop.com/plansshare/air_filter_downdraft_sanding_table.htm
   http://www.rockler.com/findit.cfm?page=10169&cookietest=1
   http://www.lakethompson.com/bhww/tips.htm
   http://www.woodworkersworkshop.com/cached_files/9768_files/I'm planning a variant on the the "Real thing" one.
   Edward

4. 
   HowardAcheson | Jun 26, 2007 03:12am | #23

   The two most important criteria for an air cleaner are the CFM and the filters. You want a CFM factor that will clean the size of your shop and a filter that removes the particle size that you are concerned about.To determine the size or required air flow, use this formula: Volume of your shop (Length x width x Height) times Number of air changes per hour (typically 6 - 8) divided by 60. This will give you an answer in Cubic Feet per Minute which is how air cleaners are measured. MOST AIR CLEANER MANUFACTURERS RATE THE CFM OF THE FAN ONLY, but there are losses due to the filters. If you are building your own or if the air cleaner you are purchasing rates only the fan, figure you will lose about 25 - 40% for filtering losses.As important as the air cleaner size is how and where you mount it. Try to mount at about 8-10 feet above the floor (no lower than 6'or 2/3 of the floor to ceiling distance if less than 8' ceiling). Mount along the longest wall so the intake is approximately 1/3 the distance from the shorter wall. Mount no further than 4-6 inches from the wall.The exhaust is the largest determiner of the circulation pattern. You are trying to encourage circulation parallel to the floor/ceiling so ceiling mounting is not recommended. Use a smoke stick (or a cigar) to observe and maximize circulation. Use a secondary fan to direct air to the intake if necessary. Also, consider that a standard 24" floor fan moves a lot of air and, in some shops, just positioning it in a doorway with a window or other door open can accomplish as much or more than an air cleaner. It's all in the circulation patterns.The exhaust is the clean air so that is where you want to position yourself. Do not place the air cleaner over the a dust producer. That will guarantee that the operator will be in direct line between the dust producer and the air cleaner. The operator wants to be in the clean air stream. If the dust has to pass your nose to get to the air cleaner, you get no benefits. If you have an odd shaped shop, two smaller units may be better than one large one.DO NOT RELY ON A AIR CLEANER TO ACT AS A DUST COLLECTOR. The purpose of and air cleaner is to keep airborne dust in suspension and reduce airborne dust as quickly as possible AFTER THE DUST PRODUCER HAS BEEN TURNED OFF. Finally, if you are looking for health benefits, you will not find any air cleaner manufacturer that makes health claims because there are few health benefits. CATCHING DUST AT IT'S SOURCE IS THE BEST LONG TERM GOAL.Howie.........

1. 
   wilburpan | Jun 26, 2007 03:21am | #24

   I would agree with everything Howard says, but I would go for about 25 air exchanges per hour instead of 6-8 exchanges per hour. It's easy to accomplish (simply install more air cleaners) and it will greatly help improve the rate at which your air cleaner will clear the air of dust.

2. 
   byhammerandhand | Jun 22, 2007 02:00am | #17

   ef has it right -- when someone swaps out a furnace, the squirrel cage becomes so much scrap steel. Pick one up for a six-pack or for hauling away.The one I have was 3 speed. The biggest problem I had was finding a 4 position switch, so I have an On-off-on toggle switch, giving me "high" and "low" settings.Other posters are right, it's the fine (less than 3 microns, or is it less than 1?) that do the health damage. So are you looking for health or sanitation?

1. 
   tinkerer2 | Jun 24, 2007 08:30am | #21

   I would be interested in getting a 4 position switch for my three speed squirrel cage fan.  Could you tell me where you found yours.  I think it is the filter or filters that determine how will it filters rather that the fan.  What kind of filters do you use?

1. 
   forestgirl | Jun 26, 2007 12:45am | #22

   Tinkerer2, I think most of the commercial air scrubbers for small shops use a pre-filter, such as a pleated furnace filter, with a multi-pocket bag filter such as this one for the serious filtration.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

1. 
   tinkerer2 | Jun 27, 2007 07:09am | #27

   Thanks Jamie,  I've filed that away for when I get ready to put the air cleaner up. 

3. 
   JohnWW | Jun 21, 2007 04:37pm | #6

   A dimmer switch can control the speed of the small high speed universal motors such as a router, but they won't work on the larger induction motors that power blowers and box fans.  Many of the larger fan motors have variable speeds but that has to be built into the wiring of the motor, it can't be added later.

   John White, Shop Manager, Fine Woodworking Magazine

1. 
   kummell | Jun 21, 2007 05:49pm | #7

   thanks John - I didn't know the theory behind it, but I had a hunch my thinking was flawed...  have a great day.

   Matt

2. 
   t_mauery | Jun 21, 2007 06:44pm | #8

   Also, dimmer switches found at local hardware stores are generally only rated to about 600 W.  I'm sure you find bigger ones, but the price probably increases exponentially.

4. 
   Ronaway | Jun 21, 2007 09:20pm | #11

   Filtering efficiency for our shops is much different than what is required for our homes. The standard blue colored furnace filters do not provide anywhere near the efficiency that we need to clean the air in our shops. Let's face it the environment is different and therefore requires a different level of filtration. I think a polyester prefilter in front on a high effiency pleated filter is what is required to do the job. With the standard furnace filters I think you are just moving the dust around and keeping it stirred up in the air.

   Ron Brese

   If you're too open minded your brains will fall out.
1. 
   zolton | Jun 22, 2007 01:55am | #15

   True, we do need better filtration in shops than in homes. There's lots more dust around.

   However, there are higher efficiency furnace filters that do a reasonable job of straining dust out of the air. That's what I use. They're about ten bucks each, and I replace them once a year or so. Otherwise I just vacuum them off. They do trap an amazing amount of dust - even very fine stuff.   Zolton

5. 
   frenchy | Jun 22, 2007 11:14pm | #20

   Kummell

     Do this little simple test before using furnace filters.. Grab one. and dump some sawdust on it.  Fine sawdust like a lot of equipment makes.. make sure you do it over a sheet to look at the results. Then run a fan,  any fan at the filter.   When finished be sure to apologise to your wife for getting dust all over her sheet.

   I realize my smart azzed remark might have gone over some peoples head so I'll be a little more blunt.

    furnace filters are ok about removing nice big chunks of stuff but lousy at removing dust.  the really fine stuff that is doing you health harm is going to go flying by and into the air with a furnace filter.. use one of the really good filters and you'll spend your time either trying to knock the dust off it so you get some air flow or living with a system that doesn't do much..

   
   

   ---

   Edited 6/23/2007 8:23 am ET by frenchy

6. 
   MOwoodworker | Jun 27, 2007 03:30am | #25

   I make a homemade air filter useing a 20in Box fan and two 20in filters.  It works perrty good in my 15'x30' Shop.  I used some 1/4in pliewood to make a little box to house the fan and make the filters replacalbe. 

1. 
   frenchy | Jun 27, 2007 06:24am | #26

   MOwoodworker,

       Please test your filters prior to use..  take some dust and put it on a filter.   Then blow a fan at the filter.. any dust that get's past is something that your lungs will need to deal with..

    Fiberglas filters are very good at flowing air,, they are not terribly good at filtering things..

    Paper elements on the other hand do a good job of filtering but they don't allow much air to flow as they fill up with dust..

    

1. 
   forestgirl | Jun 27, 2007 07:15am | #28

   "...any dust that get's past is something that your lungs will need to deal with.."  Keeping in mind, the absolute worst dust for your lungs is the stuff you probably can't see with the naked eye.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)