Clean Air (Dust Collector, Air filter etc)

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Forum topic by agallant posted 08-26-2014 02:57 PM 1408 views 1 time favorited 11 replies Add to Favorites Watch
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551 posts in 2885 days

08-26-2014 02:57 PM

Please educate me on dust collectors and air filtration systems. Currently I have a 1HP dust collector connected to my unisaw. I don’t know what brand it is, I bought it off of Craigslist. it looks like a generic to the 1HP HF dust collector. It does not do a very good job, The air seams dusty when its on and there is dust left on the saw after use.

The saw dust around the shop is driving me crazy. I would like to get the shop as clean as possible in terms of air quality which probably means stepping up to a 2HP and some sort of air cleaner. All of my tools are on wheels. I don’t know if I want to get in to hard lines and gates, I can just change the hose from machine to machine as I need.

Tips, advice, recommendations are appreciated.

11 replies so far

View timbertailor's profile


1594 posts in 1423 days

#1 posted 08-26-2014 03:02 PM

An inexpensive and popular solution is the Harbor Freight 2HP dust collector. Add a Wynn Environmental 0.5micron filter, a Thien Cyclone (homemade), and a few plumbing mods, and you have a very effective solution for under $350.

Lots of good videos on YouTube if you would like to see what people are doing to get the most out of their systems. I too do not have an elaborate plumbing system either. I just wheel it up to whatever machine I am using. Keeps the plumbing costs down and the runs short for better DC.

-- Brad, Texas,

View agallant's profile


551 posts in 2885 days

#2 posted 08-27-2014 04:38 PM

Would there be an advantage on buying a Delta,Jet or whatever vs the 2HP HF DC? If I am not going to do much better than so be it I will get the 2HP HF one but are the other ones worth $800 more?

View English's profile


655 posts in 1476 days

#3 posted 08-27-2014 11:49 PM

The goal with dust collection is to collect the chips and the fine dust from you saws and bits. The HF 2 hp unit is a good chip collector right out of the box as designed. It is a roll around with a 10” impeller and with a short hose to connect to your tools. It can deliver a Static pressure of 7” at no flow. The CFM through a 4” flex hose connected directly to the unit will be in the 350- 400 cfm range.

If you add a separator like a thien top hat. The static will be reduced by 4.5”. If still used has a roll around with a section of 4” hose. The unit may be able to produce 200 cfm. 200 CFM will still pick up chips close to the tool port connection but the velocity of the air flow has now reduced so that there is no chance to pick up the fine dust released by your saw blades and bits.

If you add duct work with blast gates, wyes, 90 elbow, and straight duct with flex to connect the tool ports. The system will start having issues just getting the chips back to the collector due to low velocity. And at some point will clog up the duct work.

A unit with a larger impeller will provide more static pressure. The Grizzly 1.5 hp unit has a 12 3/4” impeller can provide 9” of static pressure. With the higher static there would be 4.5 left after the top hat separator. With 4.5” of static you could get as much as 300 cfm through the hose connected to the unit. Still even with this unit adding duct work will reduce the static and if enough duct is added the system will clog.

For these reasons systems designed to connect to fixed duct work should be able to produce at least 12” of static pressure and have a cfm rating at 7” to 8” of static loss of 1000 cfm for good fine dust collection.

And yes the larger more expensive units with cyclones are worth the additional $800. That is if you wish to keep the dust out of your lungs.

-- John, Suffolk Virgina

View mrg's profile


824 posts in 2998 days

#4 posted 08-28-2014 02:40 AM

Change the filter bag, it’s probably a 5 micron bag hence the dust.

-- mrg

View Redoak49's profile


3246 posts in 1987 days

#5 posted 08-28-2014 11:55 AM

A lot depends where your shop is located. I am lucky as I can have my dust collector located in my garage just outside of my shop.

A good dust collector is a critical part of your shop for your health and in my case keeping my wife happy by not having dust get into the house.

If you buy a good one now, you will not have to buy another one for a long time.

View Bill White's profile

Bill White

4930 posts in 3959 days

#6 posted 08-28-2014 01:33 PM

I changed the filter bags on my HF to ones from Highland Woodworking. BIG difference in dust collection. Not as good as one of the pleated filters, but not nearly as expensive as adding all the other bells and whistles.
They are felted bags. More surface area for trapping dust. Check ‘em out.


View crank49's profile


4030 posts in 2970 days

#7 posted 08-28-2014 02:30 PM

I know there will be opposition to this advice, but I will offer it anyway.
After being in charge of all the environmental controls for a foundry for 20 years I think I know at least something that should be useful for cleaning the air in a small wood shop.

The HF collector is about the best value I have found in single stage dust collectors anywhere.
It has less power than advertised, less CFM and lower static pressure than advertised, but it is still the most bang for the buck out there.
I haven’t felt compelled to test the pressure and CFM of my HF 2HP DC, but I think I will do so and post it on LJ.
My unit handles my table saw or my jointer or band saw just fine.
I will say that I think the numbers posted by “English” above seem a little low.

Now, as to the question “are large, more expensive units with cyclones worth $800 difference?”.
That’s like asking, “Is fillet mignon worth 5 times as much as hamburger?”
Depends on how much you like fillet I suppose. Or how many meals you need to get out of a $100.

You are comparing two different things.

Now, if you want to know if the HF 2HP will outperform your existing 1HP unit, I’ll say YES.
Could you get more performance out of the existing 1HP unit? Again, YES.

You don’t gain performance by adding a Thein separator to a HF 2HP DC. You gain convenience because the can is easier to dump than the plastic bag. And you save wear and tear on the fan because less particulate matter is being sucked through the impellor. But, the Thein separator, or an add-on cyclone will both impose severe static pressure loss on the system and that reduces the CFM available.

However you can achieve both of these things with a simple drop out container before the fan, preferably close to the dust source. And, this will only cost about 1” to 2” static drop.

The replacement of the filter bag with a pleated media cartridge filter will both increase the CFM available and provide a substantial improvement in the air quality in the shop. It does this by increasing the surface area of the filter. More area = less pressure loss and therefore more flow. And more area = less velocity of flow through the media and that increases the filter’s ability to capture dust.

Bottom line, I would have a HF collector with a replacement 0.5 micron filter and a 30 gallon metal can drop-out next to my table saw and jointer. Then I would buy, or build, a shop air filter that would run most of the time.
If I had more need for capacity I would have a second HF unit, modified as above.

View English's profile


655 posts in 1476 days

#8 posted 08-28-2014 04:40 PM

The numbers I quoted came from a review of the HF dust collector done by Bill Pentz. Bill Pentz spent literally years studying dust collection for small hobby shops, you can red his work at: . After reading his HF review I made some test of my own and found that with no separator, and only 10 feet of 4” hose connected to my HF, I was only getting 200 cfm of air flow. This did a great job of collecting the chips. My HF had the Wynn filter upgrade, so I was not recycling dust back into the room. But I always had dust floating around in the air after using my machine for a while. The worst dust, the 1 micron and less you can’t even see.

Still as I stated up front,if you wish to collect chips, the HF is a great collector, I used to have one, used it for years. If you wish to collect the fine dust that causes lung issues as I have.. you will need to get 800 cfm or more at your dust port on the machine. No DC made for the hobby market today can do this though a 4” port. The static required would be greater than 15”. You need to modify the port design on your machines as well.

The HF dust collector will do a good job keeping your shop clean, but not your lungs.

link to Pentz HF review

-- John, Suffolk Virgina

View crank49's profile


4030 posts in 2970 days

#9 posted 08-28-2014 07:52 PM

I am fully aware of the Bill Pentz site and I have read most of it. In my opinion Bill Pentz could have an agenda to promote his product. And, I probably would too, if I were in his position.

But, like I said, I intend to measure the VP, and static pressure and hence calculate the CFM of the HF collector and post it here on LJ. I just want to really know because I am fatigued with all the uninformed opinions; mine included.

I have to wonder why on earth would it take him years to study dust collection in small shops. I did a complete environmental study with all EPA permits and required studies for a facility with 300 employees and a yearly production capacity of 40,000 tons of heat treated steel castings in less than a month. That facility had over 500,000 CFM of collectors and filters and cyclones.

View Sarit's profile


549 posts in 3139 days

#10 posted 08-28-2014 08:37 PM

It took him years because he not only researched, but also developed the parameters required to achieve high levels of dust collection for a healthy environment within the confines of a home shop. In an industrial situation you can almost always go bigger to achieve what you want and/or move equipment outside if required.

EPA probably has set guidelines and recommendations and you can apply industrial solutions to meet them. And since others have done it before, its fairly easy to just copy what worked for someone else.

Home shops aren’t regulated, so he had start at the beginning and consult doctors and OSHA experts in order to come up with his own guidelines, which consequently no existing home shop tailored system met at the time. Then he had to devise a solution to meet those guidelines within a home shop setting. That is 1 phase power, 8ft ceiling height, no outdoor exhausting, and reasonable cost for a hobbyist. This meant that he really had to get down to the engineering principles used to design DC systems in order to come up with the right set of methodologies to a home shop DC system. In a sense, he is functioning as the EPA for home shops.

Imagine how long it would take for you to create all the EPA materials and the research to back them up, not just study them.

View English's profile


655 posts in 1476 days

#11 posted 08-28-2014 09:05 PM

On this site I have read several posts by members that have purchased the Dylos DC1100 Pro particle counter and checked their shops. The consistent point is that almost all hobby shops fail to meet the standards set by EPA and OSHA. Some with very large dust collectors recover quickly. The big problem is filters and the way the dust collection is handled at the machine. Dust collection seems to be an after thought on just about all tools in the hobby range. The cabinets leak, the dust collection shrouds are not sealed and so on. Table saws are the worst. Even with good over table collection when making a 54” cut in ¾” MDF, which is the standard test, most fail.

A lot of the filters out there don’t filter as well as the vendor claims, and a lot of DC have filters that don’t have enough surface area to provide good filtering.

Due to this we get the recommendation to move 1000 cfm through our machines. This high air flow is supposed to overcome the leaks and capture the dust. I have two 4” ports on my table saw, one to the blade shroud and one to an over table hood. Both of these are piped back through a 6” pipe to a DC. The static on this line is 6”, per my fan curve I am moving 1100 cfm. This matches the calculated flow through a 6” duct at 6” of static. But I still get dust on the floor in front of my saw. I don’t have a Dylos DC1100 Pro particle counter, but I know that the count would be off the chart. I am constantly looking for ways to improve the dust collection at my machines.

The HF dust collector only produces 7” of static with no flow. Once a 10’ section of flex hose is connected the static drops to 4”. These tests I did on my HF DC. If you take a Ductulator Duct Sizing Calculator Slide Chart and check you will see that 4” of static in a 4” duct should produce 250 CFM. That’s in a 100’ of 4” smooth straight round duct. 10’ of corrugated flex hose with several bends in the flex pipe will equal more static loss than 100’ of smooth straight duct. The HF DC has a 10” impeller this limits the static that can be produced. Most of the other single stage DC’s have a 12” or larger impeller and they produce a higher static pressure.

So it still gets back to what you want to do. If you are just after keeping your shop clean, a HF DC will do the job. If you are after a system that will reduce your chances of damaging your lungs you need to spend the extra $800.00 and buy a DC that has the power to move enough air through the ducting system you put in your shop.

The best way to pick a dust collector is to design your duct layout, size your ducts to collect the dust from each of your machines. Calculate the static pressure losses from your duct design. Then look for a DC that will meet you calculated needs. Buying a DC then designing your ducts is putting the cart before the horse.

-- John, Suffolk Virgina

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