A simple and cheap dust collection
I finally got around to installing a dust collection system in the shop, or I should say I finally took my health more seriously. Last year I started having breathing difficulties after working all day. It became apparent I needed to step up and spend the money now, instead of on medical bills later. Now that it is installed, I can’t believe I waited so long, it is an absolute night and day difference in how much more productive I am as well as much more enjoyable to work in the shop with out all the piles of sawdust laying around.
One of the main reasons I waited so long was the cost of the system, and the lack of room in the shop for a freestanding collector that rolls around to each machine as needed.
When I started researching how to build the system, I was overwhelmed about how complicated everybody made it. I studied chart after chart on how much airflow I needed in comparison to how far away the machine was from the collector. Then there was the pipe diameter, 7″, 6″, 4″, 3″, 2.5″ and the choices keeps on going. What was best? What would give me the best suction? What is my best bang for my buck.
Some said, to get out all the really small particles, the ones that get lodged deep in your lungs; you need a cyclone with a 5 horsepower motor. After I did all that research on what I needed I was back to the realization, that this was going to cost me a lot more money than I had. The dust collection project was put on the back burner again in favor of a new respirator and broom/dust pan. Then I was inspired to just come up with my own solution after watching Stumpy Numbs Build a low cost dust collection System, out of wood.
Now his system is way more work than I wanted to put in, and I think I could get more efficient dust collection by not using square ducts. I started out with 6″ smooth wall PVC Drain pipe for the main lines. I have seen some people use sewer pipe but that stuff was a bit more expensive, especially the fitting. I found the elbows, Wye’s, and T fittings for sewer pipe to run from $30 all the way up to $90 a fitting.
Instead of using those expensive fittings, I used 6″ metal heating duct fitting. This was another reason why I chose drainpipe over sewer pipe. The sewer pipe has a thicker wall, with that extra thickness it reduces the inside diameter to 5 3/4″. The drainage pipe inside diameter is exactly 6″. With a crimping tool, I was able to fit the metal duct into the pipe easily, and seal the two together with duct tape.
I didn’t completely use metal heating duct for the whole system because I was afraid that the power of the suction would collapse the pipe. I also would have to seal all the seams length wise, on the metal ducting. I felt the fittings where strong enough to resist collapse. They had a lot of crimping and rivets, that added some extra ridgety. I sealed all the rivets and crimp points with duct tape to prevent air leaks, possible reducing suction.
When doing the layout, I took special care to keep the 6″ pipe diameter in use for as long of the run as possible. Reducing down to 4″ or whatever size the tool dust port is, only when I get to the tool itself. I believe doing this keeps my maximum airflow in the system.
I placed blast gates at every tool, paying special attention to be sure to locate them in a convenient place, to easily operate them. Knowing myself, if it is not convenient and breaks up my workflow I will not use it.
I only used flex hose in areas where it was difficult to make the connection and at the tool dust ports.
At the dust collector itself, I built a cabinet to house the bag, and filter. The filter bags only collect down to 5 microns, which in not as efficient as a cyclone. The dust always seems to escape out the edges of the bags as well. To solve this problem, I cut vent holes in the cabinet and covered them with furnace filters. The furnace filters, filter out much smaller particles than most any other systems I have looked at including the cyclones. To keep the furnace filters from reducing airflow leaving the collector, which would reduce suction, I made the cabinet fairly large to allow the air to leave the bag before pressurizing the cabinet. On cabinet door, I installed weather stripping around the perimeter to seal it so all the air is forced through the vents with the furnace filters.
I tried to use a series of furnace filters without the original bag that came with the dust collector, and have the sawdust fall into a trashcan, but that didn’t work. There was too much turbulence in the cabinet that kept the dust suspended in the air, clogging the filters, causing a loss in suction. So I took out the filter assembly I had built and reinstalled the bag, which solved the problem.
Static electricity is BS.
When I was doing my research, I found all kinds of concerns with static electricity, and recommendations on how to ground your system to bleed off the static electricity. I live in Colorado, which is a very dry climate, it does not matter if you put the whole box of static free dryer sheets in the dryer, your clothes will still come out with static. However when it comes to the dust collection system I have had zero static discharge or shocks from touching it. I build furniture for a living so the system runs most of the day, and has every opportunity to build up static. I cannot explain it, but in my experience,I have not had any issues. All the energy people are expelling arguing over grounding your system is all for not.
The system works very well. It is like a Dyson, never loses suction even when the bag is full. I can say that in the future, if I find a good deal on a stronger blower I will upgrade, sometimes some of the larger chips take their time to tumble all the way to the bag.
I installed a floor sweep, my absolute Favorite part. However, I may have to rethink the grid; it does a good job by not letting chunks of wood be sucked up or a dropped screw. However, it does prevent the large shavings from hand plans and chisels from being easily cleaned up. On a side note. This may be why I don’t have any static build up in the system, because the metal duct is touching the ground completing the circuit, constantly discharging any static build up.
A few closing points on how to build a good dust collection system that I found to be true from the research I have done and from this system.
Use the largest blower you can afford.
- Use 6” dia. Ducting everywhere, except when attaching to the tools.
- Think aerodynamically, and use reducers that gradually reduce down to the tool port.
- Sharp changes in ducting, i.e reducers, elbows, and T’s reduce airflow
- Use wye’s not T’s to split off the main trunk. T’s reduce air flow
- Use two 45 degree elbows to change direction, 90’s create a sharp corner casing loss of air flow.
- Use as little as possible of flex hose, the ribs in the flex hose reduce air flow.
- Furnace filters can work well in a dust collection system
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