questions about Greg McCallister cyclone/baffle setup

[Big Dawg]

I read Greg McCallister's post and pictures (http://www.jpthien.com/smf/index.php?topic=90.0) of his design and setup. Very interesting, however, I have several questions:
As has been suggested by him and others, using a separate separator (garbage can) attached to your DC will likely reduce suction thus the design idea of putting the cyclone/baffle in the DC to minimize the loss.
But...unless I am missing something here...isn't Greg McCallister setup still using a garbage can separator, that is separate from the DC? So why didn't he noticed the same losses? I realize that there are less hoses since it is attached directly to the motor, but doesn't  the largest loss come from the garbage can itself?
Also, he is using 6" piping. Again, maybe I am missing something important, but no matter how large the pipe is, if it has to be eventually dropped down to 3" or 4" to connect to the power tools, don't you loose any advantage of the larger diameter pipe? The air still has to be squeezed down to fit through the smaller opening at the ends. Wouldn't that constriction take away any advantage of the larger pipe? Besides, wouldn't a larger diameter pipe reduce the suction (static pressure) developed by the DC?
Confused (My wife says I stay confused most of the time, anyway)

[expo]

I dont have the answer's to your questions, but I'm also interested in any responses.

From what I understand, the losses from the baffle/separator would be minimized in Greg's case because this particular orientation eliminated several bends which would ordinarily have to be used.

Along a similar thought... Phil have you been able to determine what the optimum diameter of the baffle would be for maximum separation and efficiency?   I could imagine that going larger could be beneficial (assuming you could find a collection container with a large enough diameter), but at some point the wouldnt the airstream slow down too much thus reducing the efficiency again?

[Greg McCallister]

See my responses in bold

As has been suggested by him and others, using a separate separator (garbage can) attached to your DC will likely reduce suction thus the design idea of putting the cyclone/baffle in the DC to minimize the loss.
But...unless I am missing something here...isn't Greg McCallister setup still using a garbage can separator, that is separate from the DC?

No actually it is part of the DC or more in the theory of a cyclone. A can separator is usually installed in stream before the impeller then exits to another separator. My version only uses one separator. The only thing I am using off of the original HF DC is the motor, impeller and housing assembly. The inlet and outlet to the filter has been expanded to 6? also.

So why didn't he noticed the same losses?

By only going through one separator there is much less loss of airflow due to turbulence and resistance. Much like those who added Phil?s baffle directly to the DC instead of using a separate can setup.
The original can separator I had was only a 4? inlet going into a lid with a 4? outlet. Turbulence was high as it did not have Phil?s baffle and separation was poor. I think you might be misunderstanding me but I never said that Phil?s design was bad as many who have made his version have noted little to no loss of air flow compared to the store bought lids without the baffle.

I realize that there are less hoses since it is attached directly to the motor, but doesn't the largest loss come from the garbage can itself?

Yes actually it is in a way but flex hose causes more loss, but being that Phil?s baffle pretty much eliminates the can from the air stream it is not as relevant. Much like those who added the baffle to the original DC have noted that there is a lot less swirling in the lower bag after adding the baffle ? less turbulence, better air flow.

Also, he is using 6" piping. Again, maybe I am missing something important, but no matter how large the pipe is, if it has to be eventually dropped down to 3" or 4" to connect to the power tools, don't you loose any advantage of the larger diameter pipe? The air still has to be squeezed down to fit through the smaller opening at the ends. Wouldn't that constriction take away any advantage of the larger pipe? Besides, wouldn't a larger diameter pipe reduce the suction (static pressure) developed by the DC?
Confused (My wife says I stay confused most of the time, anyway)

Have you ever used a shop vac with the 1.25 hose and then use the 2.25 hose and notice the difference in the amount of airflow? I think a better example would be to use a 10? piece of 4? hose and check the air flow and use a 20? section and compare the two. You will notice a noticeable reduction of the amount of air flow in the longer piece. You also need to take note that 6? pipe has less resistance (larger center stream) that does not cause as much friction or turbulence. I am not going to get into the dynamics of it but to better understand this I would highly recommend to read Bill Pentz site on Dust collection. Not that he is the authority on dust collection but there is a wealth of information there and he is the only one I know of who has explained much of what you are asking. Oh, and a DC is not the same as a shop vac. A DC is an air mover with a low static pressure compared to a shop vac with a high static pressure with lower air movement. Hope that helps explain some.
Greg

[bennybmn]

Well the original question is valid in that your separator IS before the impellor, but setup in THE most efficient way possible. Also I think having a side inlet is THE best way to go. Eliminating TWO bends, and possibly bends of a hose, will go a long way to improving your efficiency. 

Any way you do a separator, the air has to do a loop, and turn 90 degrees to go up the middle. That's where the inherent loss is. Reducing the rest is the challange!

[Greg McCallister]

Here are some pics of my latest setup with different saw (old Walker Turner cabinet) and expanded shop.
I have not sealed the piping yet as I am still trying out different setups.
My older pics in the above post are just that - old.
You will note the difference in the filter setup.
Please excuse the mess - am still in construction... ;D

[Big Dawg]

Greg:
Thanks for clearing some of my questions up. I marvel at your ingenuity in your DC setup.
But one point is still bugging me.
In your explanation to me about going to a smaller pipe from a larger pipe, you said...
Have you ever used a shop vac with the 1.25 hose and then use the 2.25 hose and notice the difference in the amount of airflow?
I agree...using a larger hose allows more air to move, as long as the hose is the same diameter all the way. My question deals with dropping down to a smaller opening from a larger opening. For example...in your example above...yes the larger 2.25" hose will pull more air, but what if I put a 1.25" coupling at the end of it. Wouldn't you see approximately the same air flow as you would, had you just used the 1.25" hose?  Aren't you creating a restriction in the airflow that will negate the larger diameter hoses benefits? Likewise, when you take a 6" hose and drop it down to 4" or even smaller, at the tool, logic tells me that you will be reducing the air flow that a normal 6" pipe would provide to the airflow that a 4" pipe would provide. So what is the advantage in using the 6" pipe unless you can keep it at 6" all the way to the tool?
I'm really not trying to be argumentative...I really am interested in learning. My logical brain just can't seem get my arms around this point.
Thanks for the help.

[Greg McCallister]

Big Dawg,

I understand your not understanding (does that make sense  ;D)
As I have stated before (maybe not here but...) I am no expert.
I guess my example was not very good now that I look at it.
Yea you can only get so much out of a pipe (airflow). What causes a loss is friction with the sidewall of the pipe and that is where your loss is at. That is why smooth wall pipe is better than flex even though you have the same internal diameter.
Short runs in most systems are not a problem and running 4" will work but to get the optimum out of your system you need larger pipe.
I will try another example....
In your home water supply, the inlet is either 1" or 3/4" which is your main trunk. Off of that you have usually 1/2" pipe going to faucets and such.
The reason for the 1" or 3/4 main is to keep the pressure up in case of one or more faucets are open at the same time (the old flush the toilet while someone is in the shower and get scolded) or when a faucet is open there is no sudden pressure drop.
DC kind of works the same but it is more friction-turbulence instead of actual pressure. I have little to no actual air flow loss at the end of a run using 6" pipe reducing down to 4" which allows the 4" to draw the max amount of air flow. I will also open more than one gate to allow more air flow through the 6" main trunk. Using only 4" over a distance will cause an air flow drop.
More like checking the flow right at the DC compared to checking it at the end of a long run using only 4" pipe.
Does that make more sense...?
Very rarely for instance will you only use one port. Table saw should have under and over blade collection. If you branch a 4" supply in half you will only get half of the possible air flow due to restriction of the amount of possible air flow. I also use two ports using my router table.
The only thing I use one port on is the joiner and planer, however those do not really produce any fine dust, more like shavings.
Did you read Bill Pentz site?

Regards,

Greg

[Big Dawg]

Oh, I think I'm starting to get your point...especially if I plan to branch off of the main pipe to 2 different places on the table saw (which I will do). In that example, I certainly can see using a 6" that you then branch off to two 4" pipes. Doing that would certainly improve the suction of the two smaller pipes. Got it.  Thanks for the better understanding.
As far as Bill Penz's site...I am slowly getting through it. I must say that his info can certainly scare the begeebees out of you, on health issues. Which was the reason for me upgrading my entire dust collection system. I got two 1/2 hp furnace blowers complete with motor, squirrel cage, housing and start capacitors. I plan to make an air scrubber out of one and thought I would use the other in a dust collection setup. I realized that the furnace motor and blower would not be good as a dust collector so plan to sell it and get the HF 2hp DC. I've heard reasonably good things about this unit. It is on sale right now. By the way, didn't you say that your setup is a HF? Is it the same motor?

[Greg McCallister]

Big Dawg,
Don't let Bills site scare you to much, as others in the woodworking community have said is that his situation with his lungs may be much different then you or I. He however does make some valid points. I mean face it, we breath all the time and there has to be partials smaller than 5 microns just floating in the air outside as well as where you work. Its inevitable but the concentrations in a wood shop are much higher is what his point is.

Not sure if it is the same motor as the one that is currently on sale but I have heard that they did a few improvements to it since I bought mine. I have had mine seems like forever (early to mid 90's). There is no actual tag on the motor but it says 2HP 20 amp peak on the fan assembly tag. Its on sale for $180.00. I guess and if you have the 20% coupon would bring it down to $150.00. That is a great deal I think. I bought mine for 138.00 shipped way back. You can't actually buy TEFC motor for that price.

I know one thing is the motor on mine is a beast. Heavy as all get out. Cast iron on the outside.
What ever you do plan on upgrading the filter. Wynn Environmental sells a kit that is quite reasonable and their service is excellent. If you need additional flex hose they have that also (they carry larger then 4"). However you will have to allow for and extra $100.00 for the filter but it is well worth it. I got .5 micron paper one but I think if I were to do it again I would opt for the 1 micron poly spun as it can be washed with a garden hose.

[Big Dawg]

Thanks for the info.
I had already purchased a 1 micron shaker felt bag from Rockler about a 2 years ago and was using it in a jerry-rigged setup. I'm almost embarrass to admit what I did to build a home made dust collector, that actually worked reasonably well. I love improvising and that is why I liked what you did.
Well here goes...try not to laugh to much...I had an old 1 hp electric leaf blower so I attached it to the bottom of a clear plastic storage container by cutting out a hole to fit the blower. This container fit the shaker bag very snug with bungee cords. I hung the shaker bag from the ceiling. Then I ran my flex hose from the intake (made mods to accept the hose) and ran it to a 5 gallon can separator (Rockler again) then to my Craftsman table saw and Delta miter saw (with blast gates). Believe it or not this "poor man's" DC worked. I know it isn't going to be as good as the professionally made DC's that I am buying, but it did reduce a lot of the dust.  As a side benefit most of the fine dust that did make it to the bag filter would settle in the clear plastic container, so that after a 2 years of use the bag had virtually no cake on the walls.
OK you can laugh...I do every time I look at my setup.

[bennybmn]

Back to the pipe diameter thing...  It's not JUST the diameter. What I mean is, it's the diameter AND the length.  For instance, if you JUST have a 4" opening at the tool, and it immediately opens up to 6", yes that will impede some flow, but not as much as a 10 foot length of 4" pipe. 

How bout an experiment. Try sucking in air thru a paper towel tube.  Now cut a hole in in a piece of cardboard the same diameter and suck air thru it. I bet it's easier...  The air flow is necked down, but it's allowed to flow freely afterwords too, as opposed to being restricted the whole length of the tube.

Hope that example makes sense... If I think of an actual explanation, as opposed to an example, I'll let you know!

[Greg McCallister]

bennybmn,
You have the concept. Sometimes it is hard to put into word what you mean in a technical manner. (even though I write technical manuals for a living)
Good analogy!

[Big Dawg]

bennybmn
Thanks for the additional explanation. I kinda understood what Greg said in his second explanation, yours just made it crystal clear.
I guess the bottom line is, if Greg's DC system markedly improved its suction power after increasing the trunk line to 6" and then branched off  to smaller diameters at the tools, then it was a total success and a great ingenious modification.
On another subject...I read in several posts that adding a "neutral vane" inside the HF separator ring improved air flow http://www.jpthien.com/smf/index.php?topic=145.0  Any thoughts on that?

[bennybmn]

The other thing that Greg brought up that I never really considered is the center stream. Basically the air right around the side of the pipe is experiencing friction from the walls of the pipe. So it moves slower. So larger pipe means more room for free flowing air in the center of the pipe. Simple but not obvious!

[Greg McCallister]

Big Dawg,
I stopped laughing now  ;D. I really did not laugh as I thought what you did with the leaf blower was a good idea. Believe it or not I was thinking along those lines at one time... ;)