SUPER SHOP-MADE DUST COLLECTOR
A "clean-air" system using Clean Stream filters.
SHOP OWNER: Al Sweet
LOCATION: Central Tennessee
For the past couple years, I knew I needed to invest in a dust collection system. I had read everything I could concerning shop dust collection and came to two conclusions: 1)I wanted a cyclone; and 2) I wanted very good filtration. I was perplexed with collection bags and the space they occupy. I was also bothered by the fact that most commercial dust collection systems employ what is called a "dirty air" system, i.e., the dirt goes through the fan on its way to the filter. "Clean air" systems put the fan after the filter.
I had recently converted my shop vacuum from the paper filter element to the Clean Stream filter element made my W.L. Gore. I was fascinated with the Clean Stream filter, the improvement in air flow and how much longer it took to load up and clog. It seemed as though Clean Stream filters lasted four times longer than the paper elements before they needed to be cleaned, and they are rated at .3 microns.
Cleaning it is simple: Knock off the caked dust and dirt, rinse the thing under the faucet, let it dry and reinstall it back in the vac. The Clean Stream instructions tell you not to rub or brush the filter surface.
I set out to design my own dust collection system and employ the Clean Stream filters. W.L. Gore & Assoc. declined to assist me in the project. They will only tell you to use their product as directed, as a replacement filter for a Sears or Shop Vac brand vacuum cleaner. So I designed and built this system from parts.
I was fortunate enough to locate a used 1,200-cfm fan at a bargain price. This unit originally came from Grainger. The motor is 2 HP, 220 VAC, single-phase and operates at 3,450 rpm. It swings a 12-in. paddle blade fan.
The lead photo (above) shows the overall look of the system from one side. The plastic knobs are holding the removable side in place, so it can be removed for cleaning. The 8-in. pipe that drops into the box comes out of the top of the cyclone. The fan is mounted on a separate cabinet with storage underneath. The fan has an 8-in. intake.
The photo at right shows the collection barrel in place under the cyclone. Two 25-lb. bags of lead shot hold the lid on the collection barrel against a seat covered with closed cell foam. As you can figure, the dirty air stream enters the cyclone where the heavy particles drop out into the barrel below, the fine dust continues on to the filter box and exits back into the room through the fan. I needed a system to keep the air in the shop since it is heated and cooled.
In order to save myself time I ordered a cyclone from Oneida Air Systems and the mounting brackets to put it up on a wall instead of building a cyclone. The cyclone has 8-in. ports so I had to reduce the diameter down to 6-in. to match the ducting in my shop, which is 6-in. galvanized steel stepping down to 4-in. steel--all grounded. I have a couple of 4-in. flexible plastic pickups that I use to connect to various tools. My shop is small and many of my tools are on wheels to be rolled out and back when needed. The Unisaw is permanently ducted with steel duct. Blast gates direct the suction where I need it to go. I elected to use the Sears "red label" Clean Stream replacement filter since it is the largest one that you can buy in places like Home Depot, Sears and catalog-order companies. The Sears Power Tool Catalog gave me the rated cfm values for their vacuum machines so it was a matter of making sure I used enough of those Clean Stream filters to handle the 1,200 cfm fan--in this case 6 filters. I designed the filter box so that the Clean Stream filters would be used in the same way they are in a shop vac - sitting vertical with the exhaust air being pulled through the center of the filter.
Mating edges on the box have closed cell foam tape on them to seal tightly. I put separate strips of wood around the sides for the threaded inserts so I would not diminish the sealing area on the edges of the box and it's baffles. The knobs use 1/4-20 threads and mate with the threaded inserts.
In the picture at left, you'll notice the filter box has the clean-out door removed. The baffles on the left side direct the air flow into the bottom of the box where the air can get to the filters. The board that holds the filters had the holes cut with a swing type circle cutter and routed with a round over cutter to fit the curve of the filter. The steel bars going across the top of the filter holes are raised so they do not impede air flow and are 1/8" X 1 1/2" cold rolled steel. Threaded rods extend down through the center of the filters where a wing nut and rubber washer seal off the end of the filter and hold it in place. The rubber washer and wing nut come with the Clean Stream filter. I used birch faced plywood with a poplar core to make the filter box. I finished it with three coats of shellac inside and out.
One thing I could have done to save space would have been to mount the fan on top of the filter box instead of beside the filter box. I thought it best to keep any vibration from the motor away from the filter box but now I really don't think that would matter much since the fan seems to be well balanced.
The system works like a dream. The cyclone collects 98% of the sawdust. It breaks up the larger particles of sawdust from the planer and jointer and deposits them in the barrel, almost in a compacted state. I was worried that the barrel would fill up too fast but it does not. Half a barrel of sawdust equates to about 150 board feet of cherry planed from 1 1/8" thick down to 3/4" and includes sawing, jointing and sanding.
I have not yet cleaned the filters, and I expect several barrels of sawdust to accumulate before they do need cleaned. I tested the system by putting a filter trap on the exhaust air from the fan to see if any dust was getting through the system. Nothing gets through except clean air. If I had it to do over again I would do the same thing. An extra treat was to turn the system on and off via remote control.. . . Al Sweet
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