Harbor Freight 2HP Dust Collector Air Flow Measurements

I've been asked several times about the air flow on my modified two-stage Harbor Freight dust collection system with a Thien baffle and Wynn Environmental filter, so I picked up an inexpensive anemometer to see if I can finally give an accurate answer. In this video, I measure several different parts of the system, and show how the meter is set up for each one. If I made any mistakes in the process, let me know in the comments and I'll make the corrections here in the video description.
CORRECTIONS: At 2:05, I meant one square foot, not one cubic foot. You measure the square footage of the opening to measure how many cubic feet of air is passing through. Of course, I said this right before joking about my math skills, and then proceeded to add a graphic to the video that matched my spoken mistake. I also misspoke the decimal point a couple times, even though it was showing correctly on the meter (zero point seven one, instead of point zero seven one).
Central Machinery 2Hp Dust Collector: www.harborfreight.com/2-hp-in...
You can buy Wynn filters at wynnenv.com/woodworking-filters/. The current (2021) model number for the filter I put in my system is 35C222NANO. They also make a 35B222NANO, which is the same thing but with a removable top cap.
Proster Handheld Anemometer: amzn.to/3B07gly
Rockler 4” x 4' stretch hose: amzn.to/38VGuQ5
Skywalker 14' trampoline (for cardboard): amzn.to/3z7I5N5
Chapters
0:00 Introduction
1:26 Explaining the process
4:15 How to set up the anemometer
6:08 End of hose, dirty filter
6:49 Cleaning the filter
9:29 End of hose, clean filter
10:12 Y-splitter
11:13 Under the impeller
15:10 Cardboard duct
The old videos showing how I built the system are at this playlist:
• Harbor Freight 2HP Dus...
This video is not sponsored. I paid for everything and used my own time. As an Amazon Associate, I may earn a small commission if you use the Amazon links to make a purchase.

[@MillfieldWheels]

Hi Ben, I've had a few attempts at improving dust removal in my shop. The only thing missing from your excellent video was a test from the end of the hose with the first stage chip collector removed. There are quite a few YT videos with similar systems to yours. A lot of them have a first stage collector cyclone type gadget. I used a cyclone system when I had a shop vac as it enabled me to collect nearly 100 liters of waste and kept the shop vac pretty empty. Now I use a bag system similar to yours I've ditched the cyclone as it serves no purpose and all waste goes to the bag. So no need to separate small and large waste and just one bag to empty. I'm using the Record Power wall mounted Cam Vac system which is a suction system rather than a blower system like yours and works great. Great video. Keep it up.

[@TheSnekkerShow]

I had to look up the CamVac. Looks like an interesting system. What's the level of effort to change the bags?

[@jhans3278]

Great video! I wish all the KZbinrs who modify their DC systems would publish the data similar to you. Thanks.

[@CALDues]

😂 Wait, you're saying a free box with every trampoline no added fees or hidden costs?!?!? I'm so glad I revisited this episode of the Snekker Show. You have such natural delivery, Thanks.

[@TheSnekkerShow]

Unfortunately, I forgot to report the box on my taxes and later got audited. With interest, they took three sides of it.

[@dabeamer42]

Thanks for the info! I just bought one of those HF dust collector things, and ordered one of those filters from Wynn. Once the parts are delivered, I'll start some serious sucking. The days of the shop vac whine are almost over. Now it's off to your videos on the other mods to the HF rig. I'm guessing that the Wynn filter is the biggest difference between your numbers and the manufacturer's claim. When the mfr runs their test, they have their sieve-like dust bag on top, which I'm guessing doesn't slow things down much. And I love the deadpan delivery.

[@TheSnekkerShow]

I'm glad it was helpful. My guess is that the manufacturer tests air flow with no bag at all. I was going to compare the original bag to the Wynn filter, but I ingeniously threw out the bag just weeks before deciding to make this video.

[@TigerCarpenter]

truly enjoyed it and thank you for being one of those people who are actually curious how stuff works, and investigate + learn along the way. it seems like the duct has to be around the diameter of the duct system's main fan, to make the most out of it. if the duct is narrower, the flow is restricted, and I'm just guessing: if the duct is bigger than the main fan, the flow will "thin out". it would be interesting if you could confirm that the best flow is in the duct being the closest in diameter to the main fan. and obviously the smoother the surface of the duct, the better, so avoid at all cost those corrugated zig zag elbows. I think the best for the flow would be the PVC smooth pipes, but for the safety (static + sparks + micro dust = explosion ), we should use the smooth metal pipes (galvanized / zinc), and try to minimize the number of the elbows, and try to make the angle 135 degrees if possible.

[@TheSnekkerShow]

Thanks for the feedback, and great question. I'm not sure where the perfect balance is, but reducing the diameter of the path will reduce flow (CFM), while increasing velocity. I just measured the end of the 4" hose and the end of the large duct again, and the air speed at the 4" fitting was 105 km/h, and the end of the cardboard duct was 6 km/h, both with a similar CFM reading. Four-inch hose is the standard at the power-tool end of most dust collection systems, coming from a five or six-inch port closer to the impeller, but probably a combination of the size of the impeller and the power of the motor determine at what size the duct will start to underperform. I've heard the same warnings about static explosions in dust collection systems, but I've never heard of it actually happening. I think enough people use PVC that there would be more stories of explosions if it was an actual risk.

[@chrispingel9607]

kzbin.info/www/bejne/r3KVY56Kqbtnjqs this video explains a lot about the myths about static, pvc, and grounding.

[@TheSnekkerShow]

CORRECTIONS: At 2:05, I meant one square foot, not one cubic foot. You measure the square footage of the opening to measure how many cubic feet of air is passing through. Of course, I said this right before joking about my math skills, and then proceeded to add a graphic to the video that matched my spoken mistake. I also misspoke the decimal point a couple times, even though it was showing correctly on the meter (zero point seven one, instead of point zero seven one).

[@woodshopnerdery]

Wow, great video! You got it right, I have seen many YT videos get it wrong. I have heard cyclones separators, of any type, create about a 20% reduction in air flow. Looks like that is about what you got between the lower intake and cyclone intake measurements. So, there may be some tall error bars on your measurements, but I think you are in the ballpark and these are some very useful measurements. BTW, Oneida has an article titled "Free Fan Vs. Actual CFM Ratings - What's the Difference?" you may be interested in. Short answer, yes, as you suspected, manufactures provide "free fan" CFM ratings, meaning no bags, no filters, no hoses. I did a similar set of tests with an almost identical anemometer. I too wondered if the fan and fan housing impacted the results so I built a simple pitot tube and manometer to test it. I have a video about it if you are interested. Built from a few dollars in parts from Menards, like a stainless steel set of travel mug straws and standard vinyl tubing. In my tests, the fan housing of the anemometer added air friction or reduce area thereby increasing air velocity over a smaller cross section and caused the CFM ratings to read artificially low. It had a big impact on my 2.25 inch coupling test since the size of the anemometer proportional to the open was quite large. For the four inch coupling test, the proportion of the anemometer housing to the opening size is less so the impact on the accuracy was smaller. I believe this is why your cardboard test showed higher CFM, because the anemometer was proportionally smaller compared to the opening and therefore robbed you of less CFM during the measurement.

[@TheSnekkerShow]

Thanks for the sanity check. Feel free to post a link to your video.

[@woodshopnerdery]

@@TheSnekkerShow Sure here is the link. Hopefully it is not blocked by YT. kzbin.info/www/bejne/o56ZdKGVhJalbs0

[@at906]

Those HF dust collector doesn't put out or I should say suck in the rated spec. I am impressed or surprised that the their baffle didn't reduce your cfm and the filter surface area is so much that cleaning only improves performance by 10%.

[@louisgriffin1785]

Snek, great set of vids and I’m planning on copying your system as well however I am considering not installing the thein trash can unit, and just using the plastic bags to collect, and just keep the Wynn filter clean, it seems like that would be a big improvement in performance although a more rigorous cleaning and maintenance schedule would be needed. Also wondering if you have experimented with modifications to the stock impeller yet? Considering that also as the Rikon doesn’t look like it’s going to be available ever again? I am mostly setting up to build Ukulele’s and guitars, do you think that is a good approach or would you consider the Thein baffle a necessity? New to instrument building and dust collection - prior to this I mostly milled large wood into small wood for model ship building obsession. Thanks for any input and huge thanks for sharing this build! Awesome!

[@TheSnekkerShow]

Thanks for the feedback. The Thein baffle isn't absolutely necessary, but I think it's a worthwhile addition. It might take a little more time to build, but you'll recoup that time by not having to change bags or clean the filter as often. I haven't done anything with my impeller yet. I looked at the Rikon, but it seemed overpriced, so I'll probably play around with a homemade alternative eventually.

[@TheFalconJetDriver]

The good news is you are being as consistent as possible with your measurements. Are your methods perfect no there are far to many variables to get finite numbers. We know that manufacturers are Braggadocious about their numbers. I think a pitot tube system would give better information compared to the anometer. The way you are having to measure the CFM. Again you are comparing apples to apples with your set up, and that is good. I have the same HF dust collection system. However I made several changes to it! I removed the HF 9.5 inch impeller and replaced it with the Rikon 12 inch impeller. That made a massive difference.. I also removed the stock vacuum port and made a new 5 inch input with a HVAC take off. I also added the Supper Dust Deputy with the 5 inch suction. For the exhaust side I too used the Wynn envioemental filter.. Mine like your set up of the fan/suction is in a straight vertical line thus reducing parasitic drag. . My filter has never contained as much dust as your! I contribute that to the Thein Baffle not being as efficient as the Supper Dust Deputy. I appreciate that you took the time to produce this video. In my opinion after spending the money I did on al the components. Even considering that the HF dust distribution system was a gift. I think I would be better off to invest in a researched and engineered system for just a few more dollars. 😁🛫

[@TheSnekkerShow]

If you ever get a chance to measure, I'd be interested in how your system's CFM compares to mine, and seeing pictures if you have any online. Sounds like a nice setup. I sometimes consider upgrading to a better out-of-the-box system, but this one works well enough that it's hard to justify the expense. It could do better with suction, but it's great with filtration and keeping the air breathable. I just looked up the Rikon impeller and they're out of stock, and kind of expensive. Now I'm kind of curious how hard it would be to enlarge the one I have now.

[@TheFalconJetDriver]

@@TheSnekkerShow I there is some way I could communicate with you directly I can give you a lot of information with pictures of what I have and the details. Like your self my system is doing the job as I expect of it so have no real need to buy a pre engineered DC system. 😁🛫

[@TheSnekkerShow]

@@TheFalconJetDriver My channel name at gmail.com, with no spaces.

[@TheFalconJetDriver]

@@TheSnekkerShow I just wanted to let you know I will work on that information this evening.😀🛫

[@edgargalvan2416]

@@TheFalconJetDriver I’m curious, what system would you consider?

[@elektrikman8834]

I believe the fan is capable of the 1550 with no load ,similar to gas milage which is done on a test dyno . If you remove the restrictive giant filter I feel you will reach the numbers you are looking for. just as the cfm changes with air flow restrictions so does the motor current ,there may be to much static pressure to get the numbers you want. that being said I just put together my harbor freight dust system and all I can say is I hope the cat hunt get in front of the suction port ,sure beats the double shop vac system I had before

[@TheSnekkerShow]

The longer I own a dust collector, the more I consider getting rid of my shop vac to free up a little more floor space. I almost never use it anymore.

[@rogerthetinker5116]

@@TheSnekkerShow If you look at the restrictive guards that are there and removed them you will see a big increase of flow. That would include the one on the exhausts side or modify the exhaust to a larger size.

[@roosterCOF]

i would look into how you set this system up rather than see how much CFM your actually pulling, you placed the barrel directly to the fan housing instead of placing the collector in between the 2, this is why your getting so much dust buildup in your filter. eliminate that bag hanging down, remove the filter from the collector, attach the fan to the top of the collector, attach the collector to the barrel, and port the exhaust end of the fan to the filter, im sure you will see quite a difference in CFM and much less dust buildup in the filter.

[@anyfoolknowthat]

So, is the cardboard moral of the story that the HF collector could handle larger diameter piping?

[@TheSnekkerShow]

No, that just confirmed that the measurement of air volume taken at the 4" hose was correct, and that I configured the meter correctly.

[@anyfoolknowthat]

@@TheSnekkerShow I’ve been curious since I got mine why the impeller ports are both 5”, but everyone connects 4” pipe/hose to it

[@TheSnekkerShow]

@@anyfoolknowthat Most power tools will take a 4" hose, but in theory, if you have a 5" outlet from the collector you can run two 4" hose simultaneously. I do that sometimes, but it's kind of pushing the practice limits of the modified HF collector.

[@elkskiutah8204]

Pretty much showe the theins are not very good. Hopefully my Oneida 4/5 will keep more dust out on my filter.

[@g8r22]

Your measurements are low because of the method you are using. The velometer itself is a restriction and does not cover the entire air flow area so the method causes air flow to bypass the instrument and go directly into the duct or fan. Unfortunately I cannot quantify the size of the error. I tested my shop vac air flow doing a duct velocity pressure traverse and got 150 CFM at 14 inches of suction at the fan inlet.

[@TheSnekkerShow]

I'm sure there's some degree of error, but I think that by entering the area of the duct being measured, the meter factors in its own size in the final reading. It's just not clear if only the fan housing or the entire meter is what's subtracted.

[@g8r22]

@@TheSnekkerShow The meter is a large obstruction because of its size relative to the small ducts you are measuring. Also the fact that you are measuring at an entry makes it worse. All the meter does is read the air velocity and multiply that by the duct cross section area. In this case the meter helps obstruct the flow. BUT, for your purposes you are more interested in relative magnitude between the multiple cases you tested so your comparison result is 100% good to go.