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Do you use an air scrubber in your workshop?

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  • Do you use an air scrubber in your workshop?

    I have a laminar flow hood with coarse+HEPA filters that I built for a previous project, which is now serving as an air scrubber for my workshop. I am thinking about upgrading it though. It wasn't designed for this duty. I need something with more throughput - the output flow vector doesn't matter.

    Pretty simple job, but before I get started, I'm just wondering if any of you use air scrubbers, and if so, what determined your choice of scrubbing unit?


  • #2
    This is probably crude and redneck compared to what you may be talking about, but many years ago I built an air cleaner using a bed sheet as a filter. The unit itself was just a base and a top, with four posts connecting the two. A fan was mounted in the top and a sheet was wrapped around the posts. For convenience I mounted an outlet box on it as well.

    It was roughly one foot square and about three feet high, so that's about twelve sq ft of 'filter' area. It definitely helped clean the air- most noticeable when I was using the table saw. Even though I used a very quiet fan motor and blade unit, it still made some noise. On a constantly running basis it became a bit annoying to me and I quit using it. If I was to give any advice it would be to get the quietest unit you can find.

    This thing could have used more filter area. At work I built a down-draft table using a furnace blower. I bought several furnace filters and folded them so I could get more surface area into the available room. I used the lowest speed connection for the motor and while you can hear it running it's not unpleasant. The keys here are large surface area filter and slow speed motor.
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


    • #3
      For a metal shop? The stuff from grinding doesn't really float for that long. So all I've used so far is a dust mask. Or are you looking at the fumes from welding? Or is it for a wood shop?
      Chilliwack BC, Canada


      • #4
        When I started doing more woodworking, I found that I was coughing a lot, presumably from the sawdust in the air. I got one of these:

        I've had it a couple of months now, and am reasonably pleased with its performance. The filters seem pretty good.
        Try to make a living, not a killing. -- Utah Phillips
        Don't believe everything you know. -- Bumper sticker
        Everybody is ignorant, only on different subjects. -- Will Rogers
        There are lots of people who mistake their imagination for their memory. - Josh Billings
        Law of Logical Argument - Anything is possible if you don't know what you are talking about.
        Don't own anything you have to feed or paint. - Hood River Blackie


        • #5
          darryl - nothing wrong with crude when it does the job Mine uses some polyfill for the coarse filter, and a regular HEPA filter from an air-con. Hierarchy is: coarse-> HEPA-> fan-> output. It is quiet, but underpowered for the job.

          BCRider - Wood, metal and plastic machining. Grinding is done under open cover in a different area. I don't have a welder yet. I am just talking about a particulate filter.

          SGW - yeah wood dust likes to hang around. It is the reason I started using the scrubber.


          • #6
            The unit I made uses the blade from a rad fan. It's pretty quiet on its own if you don't spin it too fast, but I prefer the squirrel cage fans- the largest normally found in a home furnace. That's what I used for the dust collector at work. Some of the motors have a two speed option depending on how you insert the connector. I went with slow speed and besides being acceptably quiet it still blows a fair amount of air- provided you don't have much restriction through the filter. Note- this is an air cleaner, not a traditional dust collector that sucks through a 4 inch hose.
            I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


            • #7
              Yeah, I mean an air cleaner. The intake on mine is a 350x350x150mm frame (0.3325 m^2) with polyfil stretched over it. Then a 300x300mm (0.09 m^2) HEPA filter inside the duct - the main source of restriction. Thanks for tips on fans


              • #8
                Well, I have a homebuilt filter in the garage where the woodwhacking stuff is. As previously mentioned a furnace fan with filters in the intake area. Seems to work well, but it's not my primary activity. In the shop, where the metal is munched, I have a hood and filter unit on the surface grinder. Uses a big diesel truck air filter. This is in addition to a Honeywell Air cleaner made for those of us that have allergies. Anytime I run the grinder, I have both filters running, and when the pollen count is up, I run the Honeywell. This keeps the asthma under control, as well as the grinding grit off of my machines. I won't say my shop is dust free, but it works for me.

                I cut it off twice; it's still too short
                Oregon, USA


                • #9
                  Originally posted by SGW View Post
                  When I started doing more woodworking, I found that I was coughing a lot, presumably from the sawdust in the air. I got one of these:


                  I've had it a couple of months now, and am reasonably pleased with its performance. The filters seem pretty good.
                  You could make one of these pretty easy. Not much to it. A box with a blower and filter. I've been saving an old furnace motor with a squirrel cage blower for just this purpose.



                  • #10
                    Originally posted by JoeLee View Post
                    You could make one of these pretty easy. Not much to it. A box with a blower and filter. I've been saving an old furnace motor with a squirrel cage blower for just this purpose.

                    A standard box fan with furnace filter is the quick and dirty version. They don't last, but will run for a couple months. Noisily.

                    The jet air filter actually has two filters: A larger mesh filter and a huge but fine mesh fine filter. I've never cleaned the fine mesh, but should get up on a ladder and clean the outside filter. You can use a standard furnace filter for the outside filter, most people do. I have mine mounted with chains to the ceiling to keep it out of the way and minimize noise.

                    It does a fine job of keeping the woodworking dust from covering the entire shop. Things still get dusty quickly, but not nearly as quickly as they did when I wasn't running the filter.


                    • #11
                      My wood shop uses a dust collector as the primary weapon against wood dust. I went to some great lengths to ensure a good draft at the table saw and sliding compound saw to catch the dust before it is able to get into the air. Then I massaged the dust collector itself to ensure it traps the dust well and is properly sealed on the pressurized side of the filter.

                      I also built a sanding table for my model airplane building area that uses pegboard as the working top and has two large size cleanable high grade furnace filters and an old furnace fan for air flow. This proved to work so well that I'm planning on a second similar unit for the wood working machine room as a combination air scrubber and sanding table.

                      I need to point out that so far I've managed to live without the use of a power sander other than for very occasional use. If I did more power sanding I'd push up the time table on that sanding table in addition to making up a really good collector shroud for the belt sander. The sanding table would be an excellent collector for use with palm or random orbital sanders and the like. For me it'll be mostly just used for hand sanding.

                      For the wood machine room this combo sanding table and air scrubber will be integrated with the outfeed table for the table saw. I simply won't run it when using the table saw or it'll suck the panels down and make it harder to move. But the table saw has a really good collection setup already so it's not needed when running that one machine.

                      First picture is the framing for the table showing one filter in place. The filters were seated on some really compliant foam weather strip so they self seal when the fan is sucking them down.

                      This second picture shows the filter table in place with the top tilted up to show the egg crate bracing that ensures the top stays flat and can take some load. You can also see the fan on one side without the screwed in place front cover. The cover is just a flat piece of plywood with weather strip sealing and 6 screws to hold it in place. You can see the exit vent which was given a cold air return cover to act as a bit of a diffuser.

                      And last here it is with the top down but still without the front cover over the motor area and the hinged doors over the storage area to the left. This storage area is sealed off completely from the upper plenum with about 3 inches of clearance to the filter to ensure good airflow. The fan side is as big as it is because I needed the room to work around the fan unit to attach it. Not shown in this picture is that the electrical box and motor wiring is located in the low pressure plenum and uses one of those plastic sealed boxes that has the integrated air seal flange. Using that along with some care in fitting it ensured that the switch to the motor would not be a source of an air leak and reduce the draw through the filter. The switch box was located on the side above the exit opening.

                      In use a full house worth of air flow is present but the noise level is low. If I were using it as an air scrubber I'd take more time to diffuse the exit air by poking it into a box with vents all around so it didn't stir up dust that might be on the floor.

                      The filters I used where not cheap. But they are cleanable and even washable. So I hope it turns out that they are worth the added cost and make themselves less costly over the long haul. I can't say yet since it's turned out that I have only used the table a little so far what with being focused on metal working more for the last year. So they have not required cleaning up to now. I can say that the unit is a superb dust collection table though. Nothing escapes. And there's nothing around that likes to float around and coat EVERYTHING like balsa wood dust.
                      Last edited by BCRider; 11-16-2016, 02:59 PM.
                      Chilliwack BC, Canada


                      • #12
                        Quite a while ago, I picked up one of those tube-type filters for woodworking. Just around about a foot in diameter plastic tube, coarse filter on the intake and some kind of fine filter inside, which I've never bothered to clean. It was a cheap and on-sale kind of thing and I didn't expect much from it. It's been great. If it packed it in, I'd really miss it.

                        I hung it up on the rafters by the included straps. Turn it on and, in a surprisingly short period of time in my 1-bay garage, it pulls out all the fine-floaty type dust you get that escapes the tablesaw or whatever. That, and a shopvac stuck in whatever tool I'm running, and dust is reasonably well controlled. It makes shop-work a lot more pleasant.

                        Occasionally, I'll vacuum off the intake filter but I've never even looked at the internal one. It still pushes air, it still takes the dust out... must have quite a bit of it trapped in the thing by now. Granted, I'm not a heavy user of the woodworking tools, but I've done my share, and it's run up there for something like a decade. Not exactly what I'd call high-maintenance.

                        I highly recommend even a basic attempt at dust control... makes for a much nicer shop to work in.



                        • #13
                          'so it didn't stir up dust that might be on the floor.' Good point- mine at home blew air upwards, so whenever I walked by it I got a face full of air. Annoying.
                          I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


                          • #14
                            Tim Clarke - It is routing which makes the dust for me. I have the vacuum going but dust still escapes. My filter is basically the same as a Honeywell, just with the output vectored into a laminar flow, which was achieved by cross-cutting strips from a sheet of corrugated polypropylene board (corflute etc) and gluing them together into a stack.

                            Puckdropper - What doesn't last? The fan or the filter? Also looking at furnace filters, they seems to vary greatly in particulate filtering size. From MERV 1-4 (>10mm) all the way up to MERV 17-20/HEPA (<0.3mm)

                            BCRider - Very nice bench. A reverse air hockey table Thank you for sharing it. There's one thing I can't figure out about your setup from the images - I can't see how air gets from the left filter through to the low pressure plenum. I can't see the 3 inches of clearance that you mentioned. It looks like the box the filter sits on is only open at the top.

                            Worth spending money on proper filters and PPE in general - medical treatment isn't exactly cheap either!

                            fixerdave - yes, much more pleasant with dust control. My space doesn't smell like pine anymore. But now I can again smell the residual packing grease that remains on my mill. Another job to get to...

                            Thinking of also adding a negative ion generator somewhere in the system to pick up some of what gets past the filter.
                            Last edited by Swarfer; 11-17-2016, 06:44 PM.


                            • #15
                              ...A reverse air hockey table...
                              I never thought of it that way but you're right

                              The cross bar support for the joint between the two filters you see in the second picture makes it look like it is attached to the sealing box for the storage side. But in actual fact it sits up and to the right of the top and side of the storage area. There's a good size gap between the separation bulkheads and the cross bar you can see. The perspective is just doing a really good job of hiding it. And as I said before, there's two filters at work. I'm only showing one of them in place in the pictures.
                              Last edited by BCRider; 11-17-2016, 08:11 PM.
                              Chilliwack BC, Canada