Making a cyclone chip separator for a dust collector

A dust collector should be one of the first major purchases for any woodworking shop.  Not only do they help keep things clean and tidy, they also protect your lungs from harmful airborne dust.  A dust collector is only as good as it's filter, and as filters fill up with dust it reduces airflow and efficiency.  One way to reduce this is to create a chip separating baffle, which collects most of the debris in a trash can before it reaches the filter.  This instructable will show how I created a chip separator for my dust collector.

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Step 1: The dust collector

Being on a tight budget, I chose the 2hp model from Harbor Freight.  I waited until it was on sale, and then used a 20% off coupon making the total price around $165 with tax.  I think the 2hp rating is a little overly generous, but it still can't be beat for the money.  The filter that comes with it only filters down to 5 microns, which means it won't collect the dust that is most harmful to your lungs.  Rather than spend a bunch of money on an aftermarket filter, I decided to vent my system outside, eliminating the filter completely.  I highly reccomend this approach if you're able to.

still_alive10 months ago

very good idea first off! am building one now. ?. did u finally use 4" or five inch hoses for inlet an venting? also, how long was vent to outside?

thanks, mike l.

has any thought of putting a flame under the exhaust to use the dust to heat the shop during the winter months. it would help to cut down the environmental dust down alot?
vtxmanmike1 year ago
Are you still running this setup? I have an old Grizzly single stage DC that looks just like yours. I think mine is a 1.5hp, 240 volt unit rated at 1150cfm. Mine blows a lot of dust out of the top filter bag. If I convert, I'll still be exhausting into the room, so I'll have to adapt some filter bag anyway. I built a simple cyclone in front of the DC. It does a nice job of catching the bigger stuff but the bag on the DC still fills with shavings.

Please comment as I'm ready to make a change to my DC now!
Thanks, Michael
mcheung2 years ago
Did you find a need to add any pipe extension to the blower inlet so it sticks down closer to the baffle top?
mcheung2 years ago
Really glad to find this write up. I've just bought the HF DC, and was planning a much more complex build with a large cone. My workshop is on the 4th floor of an industrial loft building right up against the freeway, so I'll be venting outside as well. Good to know the simpler Thien baffle will separate enough that chips are not making it through to the other side.
tlott3 years ago
I just built a version of this, but decided to do the chip separator without the ring on it ( I needed the ring to put a bag on because I don't have the option of venting outside.) Anyhow, I spent a couple of days on this and found, to my frustration that the airflow was EXTREMELY reduced by the addition of a barrel, so much so that the bag on the collector would not even inflate, and I'm using the same model Harbor Freight Collector. A couple of days and about 30 bucks in materials later, I would caution persons against this project.... unless you are prepared to lose about 1/3 to 1/2 of your collectors power.
bigfreeinfo3 years ago
I was just about to start building a lid for a 20 gallon trash can with a Thien
baffle. I like you design better, and I hate to just throw the center ring away and not use it. I'm going to vent to the outside through a dryer vent as well. I was wondering what the final "adjustment" to the inlet vs the slot was. Can you post a drawing of the exact position of the slot in conjunction with the inlet hose on the ring. Or email it to me?
kidharris4 years ago
I thought about doing something similar, but decided against it. My worries were.....
That the blower was not designed to be operated in a vertical position. The shaft bearings may wear out quickly since they were not meant to support the load of the shaft pulling downward against the face of the bearing. I tried to find out about the bearings in mine but the manufacturer wouldn't answer my query.

Also the blower may possibly come loose and cause some damage or tear the housing apart since it also was not designed to be pointing downward. Gravity may help pull it loose or tear it all apart. Mine is only held on to the shaft by a setscrew, which is fine in the horizontal position. I'm not sure but I think that most vertically mounted blowers utilize a bolt and oversize washer threaded into the end of the shaft to hold it on.

I was also worried that the sheetmetal housing might not be strong enough to hold the weight of the motor without bowing in a little and changing the clearance between the blower and the front of the housing.

If yours is the same as mine (and it looks it), I would put it as far away from where I was working as I could. At the very least if it came apart right next to me, it would scare the devil out of me. There is a lot of kinetic energy going on there when it is at full speed and I'm not sure how much resistance a lightweight plastic barrel and a piece of plywood would offer in the way of containing it if it starts coming apart. If it starts sounding funny I would shut it off immediately. The Chinese products are not widely known for for being quality products and I didn't want to push my luck.

So....Is it still holding up now, 6 months later?
tashiandmo (author)  kidharris4 years ago
It's holding up fine.  I had similar concerns at first, but after asking around at some of the woodworking forums, I saw that many many people had turned this and other models horizontal and still had no issues years later.  It would have been easy to leave the motor and impeller upright and use a short hose or elbow, but I decided that I liked fewer turns in the airflow and a more compact set-up.  Laying the motor and impeller horizontally is probably the most common set-up when adding a baffle or cyclone to a DC.  Even many of the commercially available cyclones have this orientation.

The impeller housing is more than strong enough to support the motor, and even if it bowed slightly, there is a disturbing amount of clearance beteen the blades and the housing.  I almost wish it would bow a little so that efficiency would improve a little.

Since writing this 'ible, I've run PVC ducting to most of my tools, and made a bunch of blast gates.  I've also rigged the assembly to lift off the barrel with a ratcheting hand winch and some pulleys, which makes emptying the barrel much easier.  I also permanently secured the exhaust to something similar to a dryer vent.
I use the same collector.  It works great but the pictured switch doesn't last long.  When mine melted, I replaced it with a heavy duty light switch.  I find it much easier to turn on and off now.
furley5 years ago
What is the reasoning behind cutting just the channel for dust and not cutting out the whole center?
tashiandmo (author)  furley5 years ago
It helps create something similar to a vortex, so that the dust and chips get trapped in the container.  If you just left it open, most of the dust and chips would blow right through and out the exhaust.  It also prevents scrubbing, which is when the dust in the container is sucked out as the container gets full.
socrateez5 years ago
If your design was a little different, you would have a true cyclonic filter. Many can be seen atop grain elevators. Many are capable of filtering below the size you indicated.  Dyson Vacuums are designed around the same science. This link is a pic of anothers attempt at just such a filter for your purpose.
Still, Kudos on the re-purposing design and "MacGyverism"
tashiandmo (author)  socrateez5 years ago
Yeah, I've seen the Bill Pentz plans for a sheet metal cyclone, but as I'm venting outside into the desert, I didn't feel it neccesary to spend that kind of time and money.  I should mention that his cyclone design combined with a good filter (ie. wynn) is by far the best option if you aren't able to vent outside.  He has excellent and comprehensive instructions for building one on his website.
I lived in Phoenix so know how dusty the natural desert environment is. I agree, venting outside in the desert isnt really contributing very much to the dust levels in the air. Nice job.