May 17 2008

Improving Shop Vac Dust Collection

Like most of us in woodworking, the shop vac is generally a rather central figure, and pulls the short straw on helping keep dust and waste collected in the workspace. The shop vac’s primary design is based around vacuuming smallish sized particulates, usually dirt into a canister, with a motor drawing air through a filter while trying to evacuate that air from the canister. Overall, the design works pretty well for most of the uses asked of it. They will even vacuum up liquids.


When I think about it, I have made it possible, directly or indirectly to be able to use a number of my power tools with my shop vac. Specifically, I have a 1/4 sheet palm sander adapted, 5 inch Random Orbital Sander, PC Saw Boss circular saw, DeWalt 621 plunge routers with a no longer available Leigh RVA1 router vacuum attachment, Hitachi chop saw with vac port in the hood, router table fence, 10 inch band saw, even the drill press, all with the ability to utilize the shop vac for dust and chip collection.

I am glad you are interested in Shop Vacuum dust collection and cleaning. I am too! I have continued to pursue the improvement of dust collection and general cleaning with the Shop Vacuum. Please have a look at a recent article I’ve written about this by following this link right here.


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Then, there is the general clean up from all the woodworking activities that do not have the direct ability to collect dust. Drilling, jig saws, all the various hand tools and since I consider all the power tools to be efficient with shop vac DC in the 85-90% chip and dust collection range, there is all the waste that escapes that needs to be cleaned up there as well, So you see, without even discussing the high volume uses on the full sized dust collection system, The shop vac is really carrying a lot of the load here.

Woodworking materials present a different challenge to the shop vac. The woodworking tool industry has adapted many tools complete with proprietary adapters to operate with a shop vac hooked to them directly. Sanders, in my opinion, should not be operated without a vacuum attached to them or some form of DC in operation during the sanding process. The atmosphere in your shop will become very unhealthy if you don’t, to say nothing of the mess. Sanders are the generator of some of the finest particulate sizes you deal with in the shop, but the saws and routers create particles in many sizes at a relatively high volume. All dust collection is doable, but there are trade offs that occur and decrease some efficiency.

For years, shop vacuums have been supplied with hoses and accessories that offer Limited capability when it comes to cleaning proficiency and dust collection. We have researched and tested many hoses, wands and accessory attachments, selecting just the best of the best, and are now offering what we feel are the best shop vacuum upgrade accessories available anywhere. They are very affordable, and you can configure these tools and hoses anyway you like, to best fit the needs of your workshop. To browse or purchase these high-performance, Top-quality accessories, please follow this link!

Two objectives the woodworker has in mind is minimizing a mess, and trying to keep the air in the shop relatively safe to breathe. The problem inherent with shop vac design is that we want it to give us filtered air from the very same filter we are clogging with fine dust, and as the filter fills with dust and clogs, the ability that the motor has to move air through that filter becomes greatly reduced. It has been determined that while it is difficult to completely isolate the filter from dust, we can scrub a great deal of the waste from the air stream before it gets to the filter. By doing this we can run the vac with higher flow efficiency, and deliver better quality filtered air for longer periods of time. This is most productive.

Over time, a number of different solutions have been offered for particle separation in shop vac systems. They run the gamut of high cost – high efficiency, to low cost – low efficiency, and all work to some degree or another. The nice thing about them is that they remove a great deal of waste from the air stream before it gets to the vacuum, and helps keep the filter cleaner and flowing air at higher volumes, longer.

The mini cyclones offered by companies like Oneida, the Dust Deputy and Clear Vue, the Mini CV06 offer the highest separation efficiency to the smallest particle sizes. This is some of the best scrubbing action available, removing most of the waste from the stream before it gets to the filters. Yet the cost to the woodworker can be difficult for some budgets. Another advantage of these designs is that the cyclonic portion of the scrubber is not taking up any of the space in the waste drum, and is separate from it. These units are desirable and a very good addition to your shop vac if you want the best separation you can get.

Going forward, there is a number of trash can lid separators, which are helpful in removing a great deal of waste from the air stream. They all work to a degree but they are realistically just trash can lids with vac hose inlets and outlets, and some take more care in the orientation of the airflow than others. As delivered the lids seem to do an adequate job of removing the large particle waste from the air stream, but a much more difficult time with the smallest particulates, like we see in dusts from exotics and MDF.

My thoughts have been for a while, that if there is any way you can help clean the air a shop vac is pulling without the material reaching the canister and filter is helpful. However, where the trash can lid separator falls short is that it is really nothing more than an in hose line expansion chamber for the shop vac, where we hope the airflow will act sort of cyclonically, allowing the materials in the air stream to fall out. At the same time, the design does little to help the air being drawn from the separator remain free of the filter clogging particulates.

Enter the Thien Cyclone Separator Lid
and Thien Cyclone Separator Baffle. Once you read up on Phil’s Thien’s page, you understand, there is the small budget / small space operation that needs better DC capability and help generating cleaner air for shop vac efficiency. I’ll just briefly say that Phil’s lid has several required design elements. It fits tightly to the container it is meant to seal. It has an inlet and outlet that fits common shop vac hoses. Its inlet is positioned in the right location to direct inlet waste stream around the perimeter of the container in a cyclonic manner. It has an outlet positioned in the center of the lid that takes air from the container in a way that keeps interference to the cyclonic airflow to a minimum.

Phil’s baffle is suspended below the air inlet and outlet about 3 to 3-1/2 inches it has a 1.125 inch slot which parallels the side of the container for 240 degrees of the circumference allowing the waste to fall out of the air stream as it slows, and fall below the level of the baffle. The baffle separates a chamber where vacuum air is drawn from the container so the air leading to the vacuum itself is separated from the waste below the baffle and the waste is not disturbed and re-introduced to the vacuum stream. Phil has a video on his site, which shows that in his 30 pound can design, it works very well, and the design is scalable.

Scalable. Nice. I wanted a 5-gallon version. I contacted Phil and asked him his thoughts. He felt there could be some issue getting the Woodcraft 2-1/2 inch Router Fence Dust Extraction Fittings (part# 85O13) properly positioned on a 5-gallon bucket so he suggested adding the baffle design to the Woodcraft Mini Dust Collection Separator Lid. (part# 143868) So I went to my local Woodcraft and obtained one.


Fortunately for me, my own shop vac was filthy with testing materials. The filter was encrusted with fines, chip sizes ranged from what random orbital sanders and saw blades make… Planing shavings, drilling wastes routing chips, Maple, walnut, poplar, even some MDF dust from jig makings. Throw in a few dead leaves and spider webs, you get the idea. It was real world shop wastes from a bunch of small projects. I dumped it all out on the shop floor and cleaned the vac, filter and all, plumbed up the Woodcraft separator, as supplied in original condition, and tested.

The heavy stuff mostly stayed in the separator until it reached a level where the outlet could get to it – suction wise, and then the rest went to the shop vac. I am pretty sure the highest percentage of all the light material went to the shop vac, and re encrusted the filter. It is such a small space and with only 17-18 inches of circumference to slow waste down in, before the Vac sucks the air back out—with an outlet exactly in line with the inlets air stream the space is just to small to really be effective. I gave the mess a 60/40 split between the Vac and the separator and took note of the particulate segregation.

I re-dumped the mess and tried vacuuming less of the pile thinking I overfilled and caused scrubbing as well as slower feed rates to emulate real world scenarios on a tool and I still got in the neighborhood of 70/30 splits between the vac and the separator. The small space is too turbulent to assure that the outlet will see cleaned air. Anything passing too near gets sucked straight through.

I cleaned the separator and dumped the mess back in the vac. As is, I will say this. Any 5-gallon bucket separator purchased as is, is not as effective as you hope it will be. But hope is not lost. The answer is in Phil’s designs.


I reworked the separator lid based on Phil’s baffle, scaled, and a moved the vac outlet to the center of the Woodcraft lid, using the same part Phil specifies for the full size design. Skip moving the outlet to the center of the lid at your own peril. My initial test proved to me that the biggest flaws the Woodcraft lid had was the inlet and outlet locations being equally opposite, and it did not need a handle. The nice thing about the design is that it is well-made, heavy duty, has most of the plumbing it needs, and fits the 5-gallon bucket very precisely. It needs no assistance to seal when the vac is running.


Testing resumed. I dumped the mess out on the floor and tested with a clean vac and filter. In test one, I sucked up the pile as fast as the vac would take it. This is not realistic; this was abusively ridiculous in terms of real world shop vac use, under all but the most severe mess cleaning scenarios. I lost no suction. I filled the separator to the underside of the Thien baffle.


I estimated the efficiency at 95-96% to that without a separator. The interior of the vac canister had a thin coating of the lightest dust, about 1/8th to 3/16ths inch at the bottom of the vac, mostly MDF and mixed fines throughout, with the heaviest concentration on the filter. Nowhere near the encrusting I observed without the baffle on the separator, and the same waste had thinly, yet fully caked the filter pre separator. The filter pleats seemed to have less than 12% of what had been embedded in them without the separator.


I cleaned and tested again. This time I fed the pile slowly; at about 1/8th or less the speed I fed it the first time, trying to emulate what real world vacuuming might be in dirty circumstances, or heavy waste collection from a tool and filled the separator to the baffle. This improved efficiency again. I witnessed improvement in the Vac by better than half, so call it 97-98%. I did however notice that on these first two tests, there was heavy waste accumulating above the baffle, and reasoned I may be over filling, so I decided to test again.


I cleaned the shop Vac a fourth time. I really am over cleaning it now. Honest. I may dream about it in scary ways though, for a night or two yet. I felt like Bill Murray in Groundhog Day, or Tommy Chong going down town to look for a job on the first three days of his summer vacation.

I tested again. I sucked up 1/4th of the pile fed at the same slow feed rate I had in Baffle test two, and then I peeked. Nice. I found nothing on top of the baffle in the separator. The vac was receiving the finest dust only, and like I said, I had been working MDF so I had some tough dust. Generally speaking, most users will not routinely see this type of fine dust unless they work MDF or tropical hardwoods. If those woods are not in use, I would expect to see cleaner filters yet.

My observations based on the first three tests with the baffle, I feel on test three the vac was 98-ish percent cleaner than with no separator in line. These are just non-scientific observations, and I’ll accept no liability for them, as I am just eyeball estimating comparative quantities. I was not able to observe the cleanliness in the vac, like Phil’s video shows on the full size Thien collector with all the additional room it has, which I feel is an attribute that enhances overall efficiency. This was not as clean as the Oneida or Clear Vue products with their true cyclones fully out of the waste container, either.

In the 5-gallon bucket, there is little space for waste with the baffle in there, but the separator lid with Thien modifications really does improve the airflow to the shop vac so much, it is worth using, you just need to monitor it, and dump it more frequently. It is more efficient when not allowed to fill too near the baffle, yet very easy to empty. No fasteners to fool with, just lift the baffle lid off and dump the bucket.

My testing isn’t concluded. I need to just observe and see how well it works under routine usage, in real world collection, working whatever woods and tools I work. I imagine it will be a bit more efficient than I have observed so far in this manner. Keeping airflow cleaner at the filter will be a boon to higher suction overall, for longer periods of time. This means cleaner shop air when sanding, and hopefully now, less sanding dust will find its way to the shop vac filter. I may see collection improvements at other tools I use it with as well, based on routinely having a cleaner filter and higher airflow, this may improve chip capture most notably at the chop saw, saw boss and router table fence.


At the 5-gallon size, this separator with the Thien modifications isn’t going to replace the real shop vac cyclones in all materials. It cleans out larger particulates on par with the cyclones, but it is not near as efficient with fine dusts. However, at around $30.00, the 5-gallon separator with Thien modifications is a vast improvement over a shop vac and a separator without one. It bears repeating, keeping air velocities higher, longer is the key to better collection, and cleaner shop air. I feel, based on the videos I have seen of all three separators, at the 30 gallon size, Phil’s design gives the mini cyclones excellent competition.

After observing its limitations at this scaled size, I would recommend this small Thien modified separator to anyone if you are on a budget, space or money wise.

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© Copyright 2008 by Rob Hanson for All Rights Reserved.

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