Dust Collection Pipe Size? "Again" !!!!

Flute Maker

Mike
User
I have the 2HP (so it says 2HP) Harbor Freight dust collector. I have the Wynn filter sitting on it with the bag under it.It has a 5" hose coming out of it going to a Thein "Top Hat" separator.Out of the separator it goes down to a 4" connection that has about 18" of flex hose and then to a 10' section of 4" pvc .At the end of the pvc it goes to 4"pvc again and about 6' of 4" flex hose then to a V shaped box that I made .(I have mixed thoughts on this box but have other things to try there....a big gulp and a smaller V shaped 6" thick "box"....My ? is would it make that much difference to change the 4" to 5" pvc???? Thanks in advance!
 

Bas

Recovering tool addict
Bas
Corporate Member
I don't think you can get PVC in 5", you'd have to use metal duct instead.

I used to have the HF dust collector with a Wynn filter. It's not bad, but 4" is probably the best you can do. 6" is definitely too big, the velocity drops too much. Given that you have a trash can separator in the mix, I'd stick with 4". I don't think you'll see significant improvement going to 5", and redoing all the connections/ fittings is not cheap.
 

drw

Donn
Corporate Member
Mike, I looked high and low for 5" PVC prior to upgrading my dust collection system. While I have heard that it does exist, I think it is like looking for a Unicorn. I finally went with 5" snap lock metal ductwork, which you can find. Regarding pipe size, it is my understanding that to achieve optimal efficiency, it is best to maintain the same size from the DC inlet until you reach the various machines, then reduce down to 4" (typical size for most of the major dust producers). Given the configuration you described, I agree with Bas...I am not sure you will see much, if any improvement.
 

Flute Maker

Mike
User
That is what I was thinking...not much improvement with 5" if I could find it... If I took the separator out and vented out side would that make much difference? Right now I intend to use it on the lathe mostly when sanding and at a small table where I do some small amounts of sanding ,using a dremel etc. and maybe on the miter saw where right now I have a shop vac on it. A lot of random thinking...Thanks for saving me $ and time experimenting .(Don't have an excess amount of either lol!!!)
 

Bas

Recovering tool addict
Bas
Corporate Member
If I took the separator out and vented out side would that make much difference?
It would. There were a number of discussions on this on Phil Thien's forum a few years ago. I believe the static pressure loss from a separator is roughly 2", which is about about 1/4 to 1/3 of what the HF unit can deliver. In other words, you should see an increase in "suction" of about 30%.

There are a lot of other factors that will impact the improvement, such as the length of your run, the type of flex hose, how many turns/ how sharp the turns are etc. Regardless, you should have a noticeable improvement. I assume that when you say you're venting outside you're also getting rid of the filter. That will help too.
 

Flute Maker

Mike
User
It would. There were a number of discussions on this on Phil Thien's forum a few years ago. I believe the static pressure loss from a separator is roughly 2", which is about about 1/4 to 1/3 of what the HF unit can deliver. In other words, you should see an increase in "suction" of about 30%.

There are a lot of other factors that will impact the improvement, such as the length of your run, the type of flex hose, how many turns/ how sharp the turns are etc. Regardless, you should have a noticeable improvement. I assume that when you say you're venting outside you're also getting rid of the filter. That will help too.
My total run isnt long at all...less than 20"...If I take the separator out and vent outside do I put a Tee in line? Leave the Wynn filter in place also I guess???? I guess I could find all these answers on line somewhere.....Thanks !
 

Oka

Oka
Corporate Member
You can get 5" pvc but at a hvac supply house. But I would reduce to 4 " if your demand is not that high. It will keep the CFM up and provide better suction @Flute Maker I used to make classical flutes ....... long time ago, as well as recorders ....... small world
 

Bas

Recovering tool addict
Bas
Corporate Member
My total run isnt long at all...less than 20"...If I take the separator out and vent outside do I put a Tee in line? Leave the Wynn filter in place also I guess???? I guess I could find all these answers on line somewhere.....Thanks !
It's much simpler than that. No tee or filter needed, just connect the outlet from the dust collector to a hose/ pipe that leads outside. I found this image on Lumberjocks that shows the setup.


You don't have to use flex, if you mount the dust collector as the same height as the hole in the wall, you can metal duct as well. But flex should be the easiest to fiddle with.

Keep in mind that if you ever attach a planer to your DC, you'll have a LOT of shavings outside. But sanding dust should not be largely inconspicuous.
 

Flute Maker

Mike
User
Oh gosh that is great.Thanks a bunch Bas.I dont use my planer much but but when I do I just put the planer right at shop door. I dont do that much at all though.....One last thought. Is there any kind of cover or whatever covering the hole outside to keep snakes and other critters out when it isnt being used? Maybe something like is on a dryer vent.
 
Last edited:

Rwe2156

DrBob
Senior User
Mike,

I strongly recommend you increase the size of your ductwork. If you do a little research you'll see that 4" ducts are restrictive for a 2HP blower. Keep in mind its more about volume of air (CFMs") than velocity. This is a common misconception because of comparisons to a shop vac, which is a different animal.

My comments are also based on experience. When I redid my DC I did quite a bit of research and went with 6" ducts. All I can say is the difference was dramatic.

I've had this set up for several years and even from 25' away, I've never had an issue with settling or clogs. I can say that I've seen a screw entering the floor sweep will be heard entering the cyclone a few seconds later.

I'm sure I've got lot of things wrong about DC but I'm confident about the ducts size.
 

Bas

Recovering tool addict
Bas
Corporate Member
Mike,

I strongly recommend you increase the size of your ductwork. If you do a little research you'll see that 4" ducts are restrictive for a 2HP blower. Keep in mind its more about volume of air (CFMs") than velocity. This is a common misconception because of comparisons to a shop vac, which is a different animal.

My comments are also based on experience. When I redid my DC I did quite a bit of research and went with 6" ducts. All I can say is the difference was dramatic.

I've had this set up for several years and even from 25' away, I've never had an issue with settling or clogs. I can say that I've seen a screw entering the floor sweep will be heard entering the cyclone a few secondsthlater.

I'm sure I've got lot of things wrong about DC but I'm confident about the ducts size.
Duct size definitely matters.

I tested my old HF unit with 6" pipe with a Wynn filter and separator (w/ Thien baffle), and chips would fall out of the air stream and get stuck along the way. On the other hand, my current 3HP cyclone can suck a block of wood through the 6" pipe without issues.

The HF "2HP" machine is on the lower end of the 2HP spectrum, compared to Delta, JET, etc. It would be more accurate to call it 1.5HP. If you vent it directly to the outside, no filter/ separator, the larger pipe should work with this machine.

Bill Pentz has a spreadsheet that factors in the # of bends, length of flex, etc. Definitely worth plugging in the numbers.
 

Flute Maker

Mike
User
I looked earlier and what comes out of the dust collector is 5". Ill see what I can come up with...as the funds allow lol. Thanks for all your help..I am definitely learning on dust collection. I knew I didnt like the way it is right now and wouldnt even use it much. (In the pic you shared that hose looks bigger than 5" .....Mine looks just like it but I took it a loose and it measures 5"
 

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