Another DC Question

[Bill Pentz]

Jim – Thank you for your kind words.

Would it be possible to build a 24" diameter cyclone, especially since my two stage unit has a 24" diameter lid, that would also be as effective as the 22" unit you describe on your web page?
Absolutely, and the 24” would be a better solution with this unit, but you are going to lose some fine dust separation efficiency. My measuring of a 22” diameter cyclone showed the find dust separation efficiency fell by nearly half. The 24” will be even worse which is why with the resale so high on one of these that I recommended using that equity to buy or build a more efficient cyclone.

When you were working with your Cincinnati Fan unit did you ever try their 3hp filter bag which attaches to a garbage can and is hung from a ceiling mount? Even though its only 5 micron filtration I was interested in it because of the sheer amount of surface area it offered.
No, I instead bought an oversized bag from AFF. It flowed more air, but also rapidly clogged because my unit just put too much dust into the filter.

Alan,

Pardon my ignorance on this subject, but the one thing I haven't seen discussed recently is if one was content to use a single stage canister type DC, could build one themselves with a 3HP or 5HP motor and create tremendous suction? Seems that most products change to a 2 stage when they get to 3HP.

Yes you can make an excellent blower to power a single stage blower for a very reasonable cost (<$200 if you scrounge a good used motor) using my Budget Blower plans. I know quite a few who have done just this and then blow their dust away outside into a big drum topped with a large open filter bag that freely passes most of the fine dust. Should they later choose to power a cyclone, they are already set with a good blower.

[Alan DuBoff]

Yes you can make an excellent single stage blower for a very reasonable cost (<$200 if you scrounge a good used motor) using my Budget Blower plans. I know quite a few who have done just this and then blow their dust away outside into a big drum topped with a large open filter bag that freely passes most of the fine dust. Should they later choose to power a cyclone, they are already set with a good blower.

Yes, this is exactly what I was thinking, that if I did get a decent motor for that, I could easily use it for a cyclone in the future if I wanted.

What about building a cyclone, less the ducting, and connect it directly to the tools? Will that work reasonably also, or does the cyclone need more ducting? That would also allow for adding in ducting later to supplement the system.

[Bill Pentz]

Alan,

What about building a cyclone, less the ducting, and connect it directly to the tools? Will that work reasonably also, or does the cyclone need more ducting? That would also allow for adding in ducting later to supplement the system.

If you go with the 14” impeller, nice Leeson 5 hp motor, and cyclone with minimal ducting you will be fine. The 15” impeller needs the extra overhead of the ducting to ensure not pulling more than the 5 hp that motor can provide.

[Bill Pentz]

Bob,

Again your responses on this thread have irritated me from too many emailing about the accuracy of your information. I realize you really dislike anyone who questions your expertise, but please look over my following detailed responses to your commentary highlighted in red. Hopefully my taking the time to respond will help educate as to why I asked you to not use me or my site as your reference. Large amounts of information that is only partially correct, incomplete, or not carefully thought through causes confusion and problems in those you are trying to help. Please be more careful.

Overall, the only reason that I can see for your even bothering to respond to this thread was to give out lots of information to perhaps make others think you had lots of expertise and personal experience then use that perspective to challenge what I already said. I personally hate to respond to topics that you have responded to simply because doing so puts me in the awkward position of having to so often hold my tongue on not pointing out concerns. In this case I already responded not only from the vantage of being fairly well versed, but also as a long time owner and user of the specific unit in question. Based upon your comments, your familiarity appears to be limited to information off my pages, the vendor pages, and prior posts from other knowledgeable people.

That blower, if you look closely, has a 5.6 amp motor, despite having a 12 1/4" impeller.
This is true only for some of the units made directly by Cincinnati Fan. Many others bought just the blower and can top adding their own motors. Some like Grainger with their Dayton brand used their own blowers, can tops, and motors. Motors also changed among vendors during the twenty some years these units have been sold, so amperage ratings do vary. Each needs to check and verify both the amps and motor service factor on their particular unit.

It's probably designed as a low-resistance set-up.
This is a high resistance setup that pulls just about double the resistance of similar sized dust collectors. The dust bin arrangement on the one of these that I owned and used for more than ten years measured with “seasoned” filter and 55-gallon drum attached at 4.3” of resistance. This is more resistance than adding a cyclone with a set of good fine filters. This constant high resistance is why this good sized impeller can be powered with a relatively low amperage motor without risking burn up. Motors burn up when a big impeller sized for a high resistance gets used in a low-resistance setup. The motor simply tries to push more air than it has amps to support.

Yes, it will move a fair amount of air, but only if the resistance is not too high.
This unit is engineered to move a maximum of 966 CFM at 4” of static pressure drawing just over 2 hp. Changing over to the 4” pipe adapter that came with mine and using 4” ducting to a nearby machine brought the airflow down to about 670 CFM on my unit with a measured static pressure of about 8”. Use of 6" ducting, hoods, ports, flex could easily add the same static pressure overhead that kills performance. Adding the roughly 2.32” of resistance for the ducting and hoods for a typical two port larger tool, this unit still moved the roughly 800 CFM needed to meet what air engineers recommend as the minimum to provide OSHA level fine dust collection on our larger tools. Adding the 1.69” for a typical longest run in a 1-car garage sized shop dropped that CFM to only 662 CFM at 8”. These with the real Cincinnati Fan blowers, not the lower performing Grainger Dayton blowers, run one of the absolute best performing industrial blowers. My testing found these Cincinnati Fan blowers consistently perform better than almost all small shop units with only the Jet and Delta dust collector blowers coming close. This again shows why a 2 hp that is an excellent chip collector is too light to be used for good fine dust collection with anything less than a minimum of ducting.

Otherwise, you'd overload the motor.
Although you mean well, you were not clear that this motor was equipped with a vendor intentionally oversized impeller to meet an already known high resistance. In this case anything a person does to reduce that resistance below about 4” puts the motor at risk of trying to move too much air causing it to overheat and burn out. Just putting on a higher airflow fine filter can put this unit at risk if you reduce the resistance below 4.1”.

You probably have plenty of suction if you just exhaust into that shop-built plenum I described. With a cartridge filter on top of that plenum, you'll reduce outlet resistance compared to your present small bag. You'll also get far better filtration.
Bob you previously failed to point out that this motor is at risk when used with under 4.1” of resistance. You then followed up providing what you say is an expert opinion that the owner of this unit should make a rectangular plenum topped with a large fine cartridge filter. You introduced some confusion by using the word plenum without a definition, then instead of using that as a true plenum meaning take off point for ducting, you use it in place of saying drop box. Your recommended large cartridge filter and this plenum will immediately drop the filter resistance by up to 3" pushing the motor to draw over its rated 2 hp. This is not a very good suggestion in terms of motor life unless you also caution that you are going to make up the needed resistance to safely run this sized impeller with ducting overhead. Again an amp meter would be a must here. With less amps than its factory setup then it has more resistance and less airflow. More amps indicate better airflow. Amps over the motor’s service factor times its amp rating means a sooner burned up motor.

Additionally, I found from my own testing and experience that plenums without a separation screen simply eat fine cartridge filters ruining them in short order. They put too much filter destroying fine dust into the cartridges, plus pack the filter pleats full of too many chips unless the plenum is made drop box sized or equipped with a separation screen. Moreover, you also forgot to mention that building this plenum in wood creates a potential fire hazard worsened by building with rectangular corners that create dust piles which also pose a fire hazard. Worse, when the airflow is restored the piles that build up in the square corners at lower airflow slam sharp chips around that ruin fine filters by poking them full of holes.

You'll also reduce suction-side losses, because you'll not have your blower mounted on it's present drum. That drum gives you resistance, and you'd be better off using that resistance for your pipes.
Trying to answer every dust collection question on every major woodworking forum is a serious challenge that often leads to little errors such as use of it’s in place of the possessive form denoting ownership for the indefinite pronoun. The error is trivial, but important because it is indicative of similar but more important errors in your responses. For example think about what you said here. You introduced suction-side losses without explaining that suction side means all resistance on the intake side of the blower such as ducting, hoods, ports, and cyclones. That also needs covered with outlet side losses meaning the overhead for our ducting, filters, etc. You then should tie those pieces together explaining that adding up all these resistances for our biggest overhead demand machine and longest run lets us size our dust collection blower so we can move any tool anywhere we want in our shops and still provide ample airflow without needing a bigger blower. Otherwise, we end up having to mostly keep our dust collection blower right next to our larger high demand tools. You also made a second far more important point that got lost in your words. What I gathered from my vantage is you believe separators don’t work well and kill the airflow when used with smaller blowers. After finding this point, I don’t agree with you, particularly for folks only interested in chip collection. A separator works wonders and saves a lot of trouble in emptying typical dust collectors. Likewise, if you don't work with toxic woods, a good dust collector that moves ample air is an excellent fine dust collection solution if you blow the fine dust away outside using a separator to keep from spraying chips and sawdust all over. You do need to do a little work to match the right size and type of separator to your airflow.

Instead of having the blower sitting on that drum, just build an open stand, like a small table. Cut a hole slightly larger than the blower inlet, and sit your blower on that table. Connect a 6" pipe to the inlet, and run it down, under that table, and across to your saw's base.

At the saw-base, run a 4" take-off to the base, (6x4x4 wye) then run the other 4" branch to your overarm blade-cover.
Depending upon the series and vintage of this dust collector the blower opening can be up to 10”, so that opening was actually set and controlled by the can top having a 6” opening. Adding a 1’ long tube to that can top opening that projected into the dust bin was the biggest positive benefit I had on my unit, but did require emptying the unit more often. My Cincinnati Fan blower on my unit opened to a full 7” when not bolted to that can lid. With a 7” opening this sized impeller generates more than 2 hp until over 7” of resistance. You should have said size the wooden hole at 6” to keep from potentially burning up your motor.

Additionally, with this motor blower combination hard pressed to move the 792 CFM required to meet the somewhat remiss OSHA fine dust collection standards for a table saw, giving away 12% of your airflow because you used two 4” pipes is also not a good idea. These two pipes constrict your airflow by a needless 12%. You should go with a 5” below and 3.5” above. The 3.5” pipe can be purchased from Wynn Environmental.

I know this may all seem picky and awkward, but the concern is very real. You should not give out advice that will burn up motors, ruin filters, and put woodworkers at higher risk of fine dust exposure and in this case even fire.

Bill

[Bob Dodge]

Bill,

Thanks so much for pointing out how wrong I am,,,,, again.

I feel "enlightened".

The competition and animosity that accompanies a lot of dc threads, just never ceases to amaze me. Why can't people, simply discuss these things dispassionately.

Sorry Bill, you're on your own. Not gonna "go there".
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Oh, What the hey, just one point

The first two paragraphs you wrote, along with the "quotes", directly contradict each other. I'm not certain you noticed.

In paragraph 3, you state;

This dc is "engineered", to move a maximum of 966 CFM at just over 4" sp......... Well yes. They ALL are . That's precisely the point at which 2 bhp is produced by a moving airstream. To be a little MORE specific, it's 2.03 bhp, with a static efficiency of 32%. That sir, raises two points.

first, the dc could move THAT load, at THAT resistance. it can also move MORE CFM, at LOWER STATIC PRESSURE, and achieve EXACTLY THE SAME bhp.

Example....1275 CFM, at 3" sp = 2.03 bhp
Conversely, 645 CFM, at 6"sp, ALSO equals 2.03 bhp.

Second.(and with your "knowledgeable background and engineer/professor/doctor/hygienist friends,should know this) How do you get 2 bhp, out of a 5.6 amp/220v motor ????????????????????????????? Understand now, why I said this dc is set-up for low static pressure operation???????

So much for "engineering"

Bob

[Ken Salisbury]

OK Guys ! ! ! you're at it again

Don't make me start editing/deleting again. Please take this issue off-line

[Stu Ablett in Tokyo Japan]

Ken, I have an honest question for you.

If member "A" notices a post by member "B", that has information in it, that to the best of the knowledge of Member "A", is incorrect, can member "A" point this out and correct it?

Just wanting to know.

BTW, I find this a very interesting thread, yes is it a bit contentious, and the posters have to be careful to watch it, but a good read and has a lot of information in it.

When someone challenges your ideas, and or research, and you have to defend it, this exchange makes for good reading and lots of exchange of ideas.

I do agree, we do not need the personal attacks.

Cheers!

[Jim Becker]

If member "A" notices a post by member "B", that has information in it, that to the best of the knowledge of Member "A", is incorrect, can member "A" point this out and correct it?

Of course...nicely and with the reasons for the error. "You're wrong!" doesn't cut it. "You're wrong because..." does. Said nicely. Healthy debate is good. Attacks are not.

[Jim Chilenski]

OK, so now I'm even more confused. Nothing new really. Are you saying if I were to remove all resistance from my dust collector, take the blower off of the drum and remove the filter bag that my motor would burn up?

"Otherwise, you'd overload the motor.
Although you mean well, you were not clear that this motor was equipped with a vendor intentionally oversized impeller to meet an already known high resistance. In this case anything a person does to reduce that resistance below about 4” puts the motor at risk of trying to move too much air causing it to overheat and burn out. Just putting on a higher airflow fine filter can put this unit at risk if you reduce the resistance below 4.1”."

Would the same thing happen if I were to run the blower with all of the blast gates closed? I don't have an amp meter and I'm not a triple-E, so I'm trying to understand what you're telling me. Please explain.

Thanks,
Jim

[Allan Johanson]

OK, so now I'm even more confused. Nothing new really. Are you saying if I were to remove all resistance from my dust collector, take the blower off of the drum and remove the filter bag that my motor would burn up?

Hi Jim,

DC blowers work harder with the more air they move. If all the blast gates are closed then it isn't flowing any air so it isn't doing much work. No worries there.

But if the resistance drops (like removing restrictions so it can flow more air), then the "work" increases and the motor load increases with it.

Here are some sample numbers with a typical 2HP DC where I slowly allowed it to flow more air:

211 cfm @ 6.6 amps
480 cfm @ 8.2 amps
634 cfm @ 9.0 amps
712 cfm @ 9.4 amps
746 cfm @ 9.6 amps
810 cfm @ 10.0 amps

But the problem is the DC has a motor with a max of 9 amps on the nameplate. Allowing it to breathe freely with a short length of pipe caused it to draw more current than the motor would like.

Bill is right.

Cheers,

Allan

[Stu Ablett in Tokyo Japan]

Jim, the way it was explained to me that made sense was to look at the blower as a pump, it pumps air.

If I close all the blast gates, the blower is not pumping anything, it sounds like heck, makes all kinds of weird noises, but it does not hurt anything. The blower is just spinning around not pumping.

If you have very little or no resistance, the blower is taking bigger and bigger bites of air to pump, thus it draws more amps, it left unrestricted, it will draw more amps than it is rated for, and burn up.

Does that make sense?

I know it is not in any kind of technical terms and or language, but sometimes that just confuses us laymen.

Hope it helps

Cheers!

[Julio Navarro]

What about stalling? If the fan is not moving any air can it move? wont the static preasure slow down the motor enough to stall/stop it?

If you have a tunnel effect where the fan cant draw any air from anywhere wont it create enough of a vacumn to stop it?

[Alan DuBoff]

Alan,

What about building a cyclone, less the ducting, and connect it directly to the tools? Will that work reasonably also, or does the cyclone need more ducting? That would also allow for adding in ducting later to supplement the system.

If you go with the 14” impeller, nice Leeson 5 hp motor, and cyclone with minimal ducting you will be fine. The 15” impeller needs the extra overhead of the ducting to ensure not pulling more than the 5 hp that motor can provide.

Ok, I might have a line on a Delta 50-853, which has a 3HP 220v single phase motor, and a double stack, I think it's single stage, but not sure. Marketing litterature says 2100cfm, would that get me 800cfm if it was connected directly to a single machine?

This might satisfy me and may be able to be used if I wanted to build a cyclone, but probably wouldn't be as powerful as a 5HP.

Any thoughts Bill?

Can the cloth bags be replaced with canisters at a reasonable price? Can canisters be built for a unit like that? I'm thinking of how I could get something like that down to .5 micron if I can pick it up at the right price, if it would hold me until I can build a cyclone.

[Jim Chilenski]

Alan / Stu,

Thanks for the replies. Less technical explainations work much better for me. Let me see if I can take this a little further. If I were to remove my duct work and the drum that my collector sits on there wouldn't be any resistance and the blower would move more air but would burn itself up. So a blower NEEDS to have the resistance that's created by the duct work, and in my case the first stage seperator, so that it doesn't burn it up the motor?

But if I close all of the blast gates the motor won't burn up because its running in a vacuum and doesn't have any air to push, so there isn't a load on it.

Thanks,
Jim

[Jim Becker]

Jim...correct. In fact, the cyclone manufacturers like Oneida caution you to not run the system without duct work attached in big, bold letters for exactly that reason.