"you don't want to buy a cyclone separator"

[henry blint]

I've been shopping for a single-tool, short-hose, small footprint, ultra-portable, dust-collection solution. I was thinking of putting together a small tower configuration on a shop-built rolling stand using a 1.5HP 850CFM blower mounted atop either an Oneida Super Dust Deputy (the new plastic one with 6" inlet and sloped ramp) or a no-name sheet metal cyclone available online. I don't have any metal cutting tools to try to make my own.

The tech guy in the dust collection department of a local woodworking supply store told me that I don't want a cyclone at all, that what I want is a standard dust collector with a large canister filter with a flapper to keep it clean and the air flowing. He said the flapper is designed to wear out, to prevent it from ruining the inside of the filter. The canister would give me the maximum CFM, whereas a cyclone separator would reduce the blower performance by ~35%.

So my questions are: 1) Does a cyclone really have that much negative impact on blower performance and 2) does a cyclone separator offer other benefits in addition to keeping the filter from getting clogged up?

[Bill Bukovec]

I use a cyclone on my shop vac and I rarely need to empty the vacuum itself. So yes, it does keep the filter from clogging up.

i don't know if a cyclone has a negative impact on the blower performance or not. My gut feeling is if there is a negative impact, it's minimal.

Bill

[henry blint]

I use a cyclone on my shop vac and I rarely need to empty the vacuum itself. So yes, it does keep the filter from clogging up.

i don't know if a cyclone has a negative impact on the blower performance or not. My gut feeling is if there is a negative impact, it's minimal.

Bill

I use a little Oneida dust deputy with my shop vac and it does work great. The shopvac's filter stays clean. I'm just not sure of the cost-benefits of the cyclone for a system that has a self-cleaning canister filter.

[Kent A Bathurst]

May I safely assume that store does not offer any cyclone DC products?

I don't buy the line about the cyclone being inherently less efficient. And 35%? Doesn't pass the smell test.

On the other benefits:
1. You drop out the majority of the material without ever seeing the filter.
2. The cyclone, or 2-stage design, means that material that drops out also never sees the impeller. The 1-stage design draws everything through the impeller. More wear on that part - but this probably is not a big deal in a small home shop, except:
3. Chunks of wood, stray nuts & bolts, small rodents, etc. don't go through the impeller.

[Chris Padilla]

Two-stage definitely works! I once "accidentally" sucked a rather large, thick towel into my system. I feared it would wrap itself violently around my impeller and burn up my bearings and or motor despite turning it off ASAP. I found the towel completely intact in the dust bin no worse for wear.

[Wade Lippman]

I regularly forget the close gates on my Grizzly 3hp and it still has plenty of suction. Don't know if the cyclone reduces the suction or not, but since I have way more than I need, who cares.
Only reason to buy a DC is that space or money is severely limited.

[henry blint]

I regularly forget the close gates on my Grizzly 3hp and it still has plenty of suction. Don't know if the cyclone reduces the suction or not, but since I have way more than I need, who cares.
Only reason to buy a DC is that space or money is severely limited.

Your 3HP is a lot more powerful than the 1.5HP portable unit I'm contemplating, so you might not notice what could be a big deal for an 850CFM unit. Also, the fine dust has to go somewhere, since I can't vent outdoors, so I will need a DC with an exhaust filter in any case, even if I were to get a cyclone.

[henry blint]

Two-stage definitely works! I once "accidentally" sucked a rather large, thick towel into my system. I feared it would wrap itself violently around my impeller and burn up my bearings and or motor despite turning it off ASAP. I found the towel completely intact in the dust bin no worse for wear.

I believe it. I have one of the tiny Oneida cyclones, and it's keeping the shopvac filter clean, and I have accidentally sucked up a small rag that went into the drum, not into the vacuum.

[henry blint]

May I safely assume that store does not offer any cyclone DC products?

Not in the small portable price range. Only the big ones that are 7ft or 8ft tall.

don't buy the line about the cyclone being inherently less efficient. And 35%? Doesn't pass the smell test.

I'm not sure what the smell is. Could be that spending $200 on a self-cleaning canister filter is better than spending $200 on a small cyclone, if one has to choose between them because of budget.

3. Chunks of wood, stray nuts & bolts, small rodents, etc. don't go through the impeller.

This is probably for me the biggest value of the cyclone -- blower insurance. It's possible I could suck up a nail or a screw from the garage floor.

So the question in front of me is a) filter canister now and cyclone later, or b) cyclone with 1-micron filter bag now with upgrade later to a nice filter.

[Michael W. Clark]

This is probably for me the biggest value of the cyclone -- blower insurance. It's possible I could suck up a nail or a screw from the garage floor.

So the question in front of me is a) filter canister now and cyclone later, or b) cyclone with 1-micron filter bag now with upgrade later to a nice filter.

I agree on the cyclone keeping big pieces out of the fan. Another benefit is going to be emptying the dust bin under the cyclone should be much easier than the bag arrangements on most baggers.

If the cyclone is doing its job, it does cost you in pressure drop, which takes more power to overcome or it will reduce the system flow (your choice). The separator on the bagger units probably has a pressure drop too, but I would imagine it is much less than a cyclone pressure drop. If you put the small cyclones on a shop vac, you don't notice a difference in performance because the shop vacs are rated probably close to 100"wg+ of static pressure. The cyclone pressure drop is a small percentage of this. However, for a centrifugal fan that only has maybe 15"wg of available SP, then the cyclone drop is a bigger percentage. Plus, the shop vac fan and centrifugal fans are completely different with differen performance curves.

You can put a bag filter on the outlet of the cyclone, but not sure how you would clean it without removing it, assuming you are blowing dust from the inside to outside. If you put it in a box, then blow dust from the outside to the inside of the bag, then you could clean the bag and the dust would fall into the box (check out industrial baghouses). The cartridge filters for hobby use open on the bottom to remove dust when you clean it by blowing from the outside to the inside.

[Kent A Bathurst]

I'm not sure what the smell is. Could be that spending $200 on a self-cleaning canister filter is better than spending $200 on a small cyclone, if one has to choose between them because of budget.

OK- I am fine with that. The "smell test" is that 35% degradation simply does not seem right. Sounds like a guy on a used car lot to me.

Also, Henry - your response introduces a new item that was not in your initial post. If , in fact, your driving concern is the $$ spent, then go get the Harbor Freight 2hp single stage. Or, better yet, Craigslist for used single stage - you will be out the door for a buck-fifty. Max. Probably closer to a c-note. It will do everything you need.

Bait-and-switch on your post, friend. I answered the questions you asked.

........in my experience, it's easy to overfill the preseparator, or to suck down something that clogs the funnel hole momentarily....

That is what is called a "management problem".

[Jim Andrew]

I have a 2hp cyclone, and overhead dc on both my tablesaws. Sometimes I notice a strip of wood I'm cutting off the edge of the board go whizzing up the hose. Sometimes I hear a block rattling along in the piping. So just 2hp is enough to grab pieces of wood off your saw. When I dump my barrel, sometimes I find lots of small pieces. So the cyclone does keep all that stuff out of your impeller.

[Alan Schaffter]

First- start looking for another woodworking supplier- that guy knows diddly squat.

". . . .a standard dust collector with a large canister filter with a flapper to keep it clean and the air flowing. He said the flapper is designed to wear out, to prevent it from ruining the inside of the filter. The canister would give me the maximum CFM, whereas a cyclone separator would reduce the blower performance by ~35%."

There is so much wrong with what he said, it is almost criminal.

Personally, you are throwing your money down a hole if you put a canister filter on a standard dust collector without a cyclone or separator. Dust will start immediately clogging the filter and immediately start reducing your suction- that's why they put the flapper there in the first place!!! In the second place some of that dust will find its way deep into the pleats and permanently clog and reduce flow through the filter. Some can actually damage the filter. Finally, using any kind of mechanical filter flapper, and using it as much as will be needed without a separator, will quickly destroy the filter media. It will actually force some small AND large dust and chips against and into standard media and can accelerate the de-bonding of any Gortex or other coating. The end result is that more and more dust will pass through the filter- you will be creating a "dust pump" AND the filter life will be greatly reduced!!!

The effect of a cyclone or other pre-separator on system performance depends on the separator AND the fan curve of the unit. My memory isn't as good as it once wast but I believe the numbers are roughly about 2 - 2.5" in. water impact on SP for a good cyclone and about 4.5+" for a trashcan or other pre-separator. Go to Cincinnati Fan or the Oneida website and find a fan curve for one of their non-cyclone systems, and see what effect 2" then 4.5" of SP has on CFM. Remember, unless you have a roll-around with a short hose, you'll also need to add the SP from hose, pipe, fittings, etc.

[Bradley Potts]

First- start looking for another woodworking supplier- that guy knows diddly squat.

". . . .a standard dust collector with a large canister filter with a flapper to keep it clean and the air flowing. He said the flapper is designed to wear out, to prevent it from ruining the inside of the filter. The canister would give me the maximum CFM, whereas a cyclone separator would reduce the blower performance by ~35%."

There is so much wrong with what he said, it is almost criminal.

Personally, you are throwing your money down a hole if you put a canister filter on a standard dust collector without a cyclone or separator. Dust will start immediately clogging the filter and immediately start reducing your suction- that's why they put the flapper there in the first place!!! In the second place some of that dust will find its way deep into the pleats and permanently clog and reduce flow through the filter. Some can actually damage the filter. Finally, using any kind of mechanical filter flapper, and using it as much as will be needed without a separator, will quickly destroy the filter media. It will actually force some small AND large dust and chips against and into standard media and can accelerate the de-bonding of any Gortex or other coating. The end result is that more and more dust will pass through the filter- you will be creating a "dust pump" AND the filter life will be greatly reduced!!!

The effect of a cyclone or other pre-separator on system performance depends on the separator AND the fan curve of the unit. My memory isn't as good as it once wast but I believe the numbers are roughly about 2 - 2.5" in. water impact on SP for a good cyclone and about 4.5+" for a trashcan or other pre-separator. Go to Cincinnati Fan or the Oneida website and find a fan curve for one of their non-cyclone systems, and see what effect 2" then 4.5" of SP has on CFM. Remember, unless you have a roll-around with a short hose, you'll also need to add the SP from hose, pipe, fittings, etc.

BINGO! This is the first really useful, factual discourse on the topic. That woodworking supply store should be removed from your list of reliable resources. As Alan has noted, the canister filters come with significant compromises:

1) The bare impeller/motor combo moves a certain amount of air.
2) Every little thing that gets added to the inlet or outlet side of the fan is going to reduce its performance, and each of those additions has its own value that is literally subtracted from the original performance value -- these reductions are basic physics.
3) Filter media restricts airflow and therefore #2 above applies to it; greater levels of filtration subtract more and more airflow, which represents lost performance. That is why the cheapo setups include 5 & 30 micron filter bags -- they flow better than the filters that trap the really harmful particulates.
4) There is an optimum area of any filter media for a given air flow: Too much air coupled with inadequate airways out, and the particulates get forced into the media itself, which clogs, and ultimately gets blown to pieces and fails; too little air flow and the system just won't suck adequately. This is why the better levels of filtration need to be bigger so that there are more smaller airways (which are more restrictive) to adequately pass/exit the given volume incoming air from that fan unit.
5) Pleated/canister filters exist because they take up less space than shaker bag filters. They cost quite a bit more too. Before buying that canister filter, you'll have to decide just how important that reduced size actually is to you.
6) Canister filters clog far faster and easier than shaker bags, because those pleats concentrate and trap the dust laden air in very tight little pleated corners.
7) Canister filters are not easy to clean.
8) If you have enough room for it, the best value for performance is a 1 micron shaker felt bag. These take up a lot more space than the canister, but as the name indicates, only require that the bag be shaken in order to clean it. They are 1/2 the cost of the canisters, and can be custom configured at little to no additional cost so they will work with ducting that places them in more convenient locations.

As numerous others have stated, a separator is essential. If I were doing it all over again, I would buy a HF 1hp - 2hp DC (~650 cfm and as low as $99) + 1micron bag from Rockler ($25 on sale now) + a Dust Deputy (on a big can) and use a hose no longer than 6' - 7'. This would all be cart mounted and moved from machine-machine and should be able to keep a TS or planer clear. The cost of this healthy setup would be about $200. Ducting is the real hidden expense in DC systems, and my approach 100% eliminates it; plus if and when you tire of moving the dust cart around a big shop (jeez I wish I had that problem), then just add another one to the other side of your shop to ease the carting about and you will still be more than $1K - $2K richer.


-- Bradley

[daniel lane]

If I were doing it all over again, I would buy a HF 1hp - 2hp DC (~650 cfm and as low as $99) + 1micron bag from Rockler ($25 on sale now) + a Dust Deputy (on a big can) and use a hose no longer than 6' - 7'. This would all be cart mounted and moved from machine-machine and should be able to keep a TS or planer clear. The cost of this healthy setup would be about $200. Ducting is the real hidden expense in DC systems, and my approach 100% eliminates it; plus if and when you tire of moving the dust cart around a big shop (jeez I wish I had that problem), then just add another one to the other side of your shop to ease the carting about and you will still be more than $1K - $2K richer.

Bradley,

Are you thinking a "dust right" sorta-cyclone lid on a can, or the Oneida dust deputy mini-cyclone? I would have thought the dust deputy highly restrictive to a DC, given the small openings, but I've not used one.


daniel