If you have been through the shop tour page, you know that our dust collection system consists of a modified old model green Harbor Freight "Central Machinery" 2 HP dust collector. It has been modified by swapping out the pitifully undersized 9" impeller, with a proper sized 12" impeller sourced from Wen tools, the part is the 3403-22 Turbofan. The dust spewing original so called filter bag was never installed, but instead the filter was replaced with a Wynn 35A MERV15 pleated filter, and to keep the filter as clean as possible while keeping air flow at a maximum I fabricated and installed a neutral vane. I am now pulling fast enough my anemometer can not read the air speed. That's not all that impressive as with the 5" inlet that means I am pulling over 1K CFM at the impeller inlet.
An old photo of the HF DC
I know I am a wierd one. MOST people run even sized dust collection ducting. 4 or 6 inch with the Harbor Freight 2HP dust collector. But even with the upgraded filter and impeller all of the experts I read tell me 6" is just too big, and 4" is too small. And, well 5.5" doesn't exist...
Cross section of a circle as you may recall is A = π * r2
4" Duct 5" Duct 6" Duct
12.566" 19.634" 28.27"
A visual comparison between 4" and 5" ABS fittings.
So... long story short, due to limitations inherent to 2HP dust collection blowers, and contrary to very popular opinion including several dust collector manufacturers, which are notorious for overstating the capability of their equipment, I opted to play it "safe" and went with 5".
Now 5" plastic hose is plentiful, with all those ribs and ridges, which would be coutner productive and I would have been better off with 4" performance wise.
Long story short, which is a rarity for me, but I removed the floor level 4" run, and replaced it with 5" runs about 3' off the floor, and a run up the wall and accross the ceiling, where I have to pull dust up I reduce to 4" sacrificing volume hopefully for velocity.
Components used in the system were bought over a long time of collecting when sales came up on the cheap, or literally castoff material from close by construction projects. But the pieces used at best prices I can find them now. Mind you, I AM going to post affiliate links where I have them, and would GREATLY appreciate you supporting my work by using them if you are doing this project, but with that in mind, I will make every effort to give you the best prices I know of available online. Very often this is NOT with anyone I have affiliates with. I appreciate your support, but I do what I do to share a budget approach to what can be a very expensive pursuit. I would rather save you a nickel than make $5.00 for myself. That might make me an idiot, but I am a firm believer into the if you bless someone, blessings will come back around to you one way or another.
Wen or Harbor Freight, or any other dust collector with bag filters, you REALLY need to upgrade your dust blowing bag filter, for a fine filtration pleated cartridge filter. The Wynn is considered the top dog in this game, but there are alternatives. Google Wynn 35a alternatives and you will come up with stuff from several vendors. Good reports on the Donaldsons, but you will need to figure out how to attach to the DC, again Wynn is the champ here... Spend a little bit more and remove the headaches.
The neutral vane is simply a piece of, well pipe that you need to form with a special curve in it that forces incoming air into the dust collector to spin along the outer edge of the separator ring, causing the dust and shavings, mostly to drop out of the air stream before moving on to the filter, this keeps the filter clean longer and keeps it from clogging up. Periodic blow downs of the filter with a compressed air blowgun, or even a leaf blower is all the maintenance your filter will need at this point. Sawdustzone.org member LCHIEN posted up his template for making the Neutral Vane for the Harbor Freight dust collector https://www.sawdustzone.org/forum/discussions/shop-setup-layout-and-design/36139-hf-neutral-vane-pictures-reposting
and I believe this should also work / fit directly with the Wen as the only difference I can see between the HF and Wen units is the paint color, and the impeller...
The branch wyes are from Wood River, which I believe is Woodcrafts house brand. Again prices on these have gone up a bit since I got ime a while ago, inflation and all, but currently at $16.49 that is way less than the nearly $30.00 each Amazon is getting for them, or nearly $50.00 each for the metal ones.
The lowest prices I could find on the aluminum HVAC tape, 5" snap lock duct, and 5" adjustable elbows was all local at Home Depot. I won't post links as your local store, say if you are in Alaska or Hawaii may have higher, or lower prices than mine. My ducting sheet metal parts are not all purchased at Home Depot either. Some of them were what you would consider scratch and dent from local construction sites, 5" seems to be a common branch size on a lot of the houses being built around here, including mine, so contractors tend to prefer to toss and start over on a $5.00 elbow VS. paying somebody $15.00 to straighten it out to use it. Look while driving through the newer neighborhoods, and if you see the stuff, don't be shy to ask!
The 5x4 reducers. I wanted smooth flowing cone reducers. Amazon is looking for $14.40 a piece for the Woodstock International 5x4 cone reducers. Grizzly.com wanted $2.25 + cheap shipping. I went with Grizzly.
Lastly and this is really a luxury, you CAN use cheap plastic duct strapping, but I opted for proper actual U clamps for my duct work to keep it secured to both the wall and ceiling.
You will need the following items to complete the install.
So aside from the remaining issue of trying to figure out how to properly collect the spewing dust off of the sliding miter saw. LOTS of research going on about that. I could design a custom hood for 3D printing, however I would want to sell something like that, and honestly there just isn't that much of a market for a cheap Harbor Freight single bevel sliding miter saw dust collection...