DC3300 Dust Collector

dusty · Post by **dusty** » Sun Feb 13, 2011 9:56 am

The DC3300 has three ports. I have almost always run with two ports closed off. I have been reasonably satisfied with dust collection but now have some reason to believe that opening those closed ports may improve efficiency.

I came to this unsubstantiated conclusion a couple weeks ago when I had hoses running to the surface planer and the belt sander, in addition to the Mark V, even though I was not using more than one SPT at a time.

Is there a technical reason that substantiates this observation or am I imaging this.

I have removed the plugs that I have had in the DC3300 for years. The unused ports are running open. I don't know if this will prove anything but that is how it is for now.

JPG · Post by **JPG** » Sun Feb 13, 2011 11:39 am

dusty wrote:The DC3300 has three ports. I have almost always run with two ports closed off. I have been reasonably satisfied with dust collection but now have some reason to believe that opening those closed ports may improve efficiency.

I came to this unsubstantiated conclusion a couple weeks ago when I had hoses running to the surface planer and the belt sander, in addition to the Mark V, even though I was not using more than one SPT at a time.

Is there a technical reason that substantiates this observation or am I imaging this.

I have removed the plugs that I have had in the DC3300 for years. The unused ports are running open. I don't know if this will prove anything but that is how it is for now.

Perhaps the impeller creates more air flow through all ports when operating pressure is less due to the open ports. Static pressure change?
?????

edflorence · Post by **edflorence** » Sun Feb 13, 2011 12:23 pm

Dusty-

For whatever this is worth (not scientific!) I have noticed the same thing.

Often after a session I will close off 2 ports and just use the hose from one to vacuum up. Sometimes I forget to re-open the other ports and the next time I run the SS in TS mode the collection is noticeably poor. As soon as I remember to open everything up, the collection improves tremendously.

dusty · Post by **dusty** » Sun Feb 13, 2011 1:23 pm

JPG40504 wrote:Perhaps the impeller creates more air flow through all ports when operating pressure is less due to the open ports. Static pressure change?
?????

I am not sure I understand. It seems to me that if the impeller is attempting to move a certain amount of air and if that air can be drawn though only one port then the suction at that port should approach maximum. That does not seem to be the case. What do I not understand?

The DC3300 is said to move 330CFM. How many CFM can be moved through a single DC3300 port? If the answer is 110CFM then I think I understand.

robinson46176 · Post by **robinson46176** » Sun Feb 13, 2011 1:58 pm

dusty wrote:I am not sure I understand. It seems to me that if the impeller is attempting to move a certain amount of air and if that air can be drawn though only one port then the suction at that port should approach maximum. That does not seem to be the case. What do I not understand?

I don't have the SS collector but this month I am using my Penn State collector on my TS-3650 by just shoving the end of the 2 1/2" hose (connected to the saw) a foot or two into the 4" hose from the collector. I previously had tried taping the gap closed but it "seemed" that it pulled the dust in better with the gap open. Like you I have absolutely no proof. Nothing scientific at all, not even sound theory. It just "seems so".

.

charlese · Post by **charlese** » Sun Feb 13, 2011 2:16 pm

Ed in Tampa has noticed that his DC 3300 operates best (when using the saw) when one additional port is open. Hasn't been noticeable in my case.

However to try to answer your question - Picture the DC trying to draw air in through a 1" hole. Or better yet(to be extreme) trying to draw air through a straw. It stands to reason that the larger intake opening will yield a larger intake - up to a point which is probably the size of the fan.

It seems that the second port being open allows more air flow through the manifold (duh!). My guess is because of this additional air flow, a little more of it is drawn through the first hose.

When I read the advertisement for the DC3300 it says air movement is the key and the 3300 will draw 330 cu.ft./ minute with 3 port open. They now offer a 4 inlet assembly.

Of course, out flowing air obstructions also limit inflowing air. If the top bag is covered tightly with a plastic bag, the in flowing air would stop. At least until something broke loose. Conversely - The larger the cloth hood = more outflowing surface = more inflowing air.

dusty · Post by **dusty** » Sun Feb 13, 2011 3:04 pm

This is exactly my point of confusion, Charlese. If the DC3300 is going to deliver 330CFM out thru the dust filter, it must also draw that volume of air in thru the hoses.

If two hoses are closed off, is there not then an attempt to pull that same volume of air thru the remaining single hose and to do so, the air would have to move at a greater velocity? At a greater velocity, the dust would then be removed more effectively (at least it seems).

By opening one additional port, it seems that that same volume of air is going to exit while the volume of air moving in thru the two hoses will be balanced (halved). Carrying that logic one step further, opening the third port would then reduce the volume of air (in each hose) to 1/3 of maximum capacity or 110 CFM.

Where is the fallacy in my logic?

shipwright · Post by **shipwright** » Sun Feb 13, 2011 8:01 pm

I'm not sure this is related, directly anyway, but in my Vancouver Island shop I have a big DC with inlets throughout the shop for my various tools. I noticed that I get better performance if the "end of the line" gate is open. I always thought that that was because if it were closed there would be a sort of vacuum created upstream of the open "Y" into the main line.

- Just another bit of data to consider.

Paul M

kalynzoo · Post by **kalynzoo** » Sun Feb 13, 2011 8:21 pm

It's been over 40 years since my last physics class, so I will not even try to justify my results. I keep two ports open, one usually attached to the tool, like the port on the bandsaw or the lower guard on the table saw, I attach the second hose to a magnetic nozzle usually attached to the lower waytubes, or the powerhead. This seems to collect most of the sawdust, and at least pull the airflow downward.

charlese · Post by **charlese** » Sun Feb 13, 2011 10:20 pm

dusty wrote:This is exactly my point of confusion, Charlese. If the DC3300 is going to deliver 330CFM out thru the dust filter, it must also draw that volume of air in thru the hoses.

If two hoses are closed off, is there not then an attempt to pull that same volume of air thru the remaining single hose and to do so, the air would have to move at a greater velocity? At a greater velocity, the dust would then be removed more effectively (at least it seems).

By opening one additional port, it seems that that same volume of air is going to exit while the volume of air moving in thru the two hoses will be balanced (halved). Carrying that logic one step further, opening the third port would then reduce the volume of air (in each hose) to 1/3 of maximum capacity or 110 CFM.

Where is the fallacy in my logic?

Here is why I have a brain problem accepting that with 2 ports open, there will be more air flow through the first.

This is from PTWFE: There is a chart in PTWFE that shows ( Being unsuccessful in copying the chart, I just copied the data)

- Flexible Hose Airflow (2 1/2" X 8' size)
One port used will give 107 CFM
2 ports used will give 100 CFM each
3 ports used will give 95 CFM each

This statement from PTWFE:
"Push the plug caps onto the inlet plugs. Then place an inlet plug assembly in any inlet not being used. These plugs help to muffle noise and slightly increase the suction power. If you desire, you can leave inlets open to help filter dust from the air."

As this chart shows, when using the small hood, there would be 107 CFM airflow through one port. Opening a second port would slightly lower the airflow to 100 CFM per port.

.