J. Phil Thien's Projects

This fella had been active gathering dust until it was made redundant with a central system. Now it's just gathering dust. It's incredibly well built with a thick poly body and sturdy frame. It's just way underpowered.

I was noticing those industrial 55 gallon twin motor shop vacs that sell for $1k and wondered what they were about. Looking at schematics I see that someone had the clever idea of mounting a couple $60 3 stage vacuum motors on a drum lid and charging a whole lot.

I'm in the process of replacing the 3300's felt bag with a twin vacuum motor box. I've taken the blower assembly out of the 3300's carcass and will use that space for the separator. I have a 30 gallon car wash soap barrel that is going to be mounted below. It's pretty thick walled but may require external ribs for support against  the 130" H2O lift of the motors. They are rated 105cfm so it will ostensibly pull 210cfm. To my knowledge static lift is not additive and lift of two is the same spas the lift of one.

I welcome advise but I have a question about the size of the intake between the motor box head unit and the separator. Typically this is set by the size of the blower. Shop vacs typically 2.5", Harbor Freight collectors 4", etc. I plan on using this mostly for sanding tools and routers so my tool inlet will always be 1.5" .  I don't know and can't find information on what effect the inlet to the blower makes when the size is not related to an impeller size.

Like with most things Thien I have confidence there is a wide range of acceptable. But, because I have no idea if it would be better to use a large or a small diameter inlet to the vacuum motor box I would appreciate the support and advice of the forum.

Thank you and Happy Holidays.

I am building a Thien top that for 1.5" duct for my power hand tools. The top hat will be "powered" by a vacuum motor because it just seems redundant to have a separate shop vac and I don't need another one and have no space in my small shop. So, the plan is to run the 1.5" duct from the tool to the top hat and I am curious what the thinking would be in terms of the size of the inlet.

For instance, one option would be to create a 4" rectangle inlet and use a round to round transition ahead of the top hat to transition from 1.5" to 4" round duct which would then transition from 4" round to a rectangle of a larger volume to create a nice column of air to drop through the slot of the Thien baffle. The top hat will be powered by a vacuum motor typically used in commercial shop vac's. I will make the top and bottom so that I can fit different height sides and experiment with the volume of the top hat. I am interested in seeing how this works.

So what does the group consciousness suggest in terms of the size of the inlet. The choice is native 1.5" or a more typical 4" inlet that has the transition accomplished in the duct prior to entering the top hat.

I would appreciate the picture, or a thousand words, your choice.

This has gotten interesting because as I was looking into replacing my 25 year old Craftsman shop vac I have run across a whole industry of commercial vacuum motor replacements for carpet cleaner extractors, Car wash interior vacuum cleaners and yes, the redoubtable and venerable wet/dry shop vac design. But there are a limited number of companies that sell the same motors to these very expensive commercial units with similar specs and costs that are very reasonable. You don't get the hoses, vacuum body, filters, etc. But for a hundred bucks +/- twenty bucks what would you say to a Triple Stage vacuum unit (meaning 3 internal to the motor cooling fans), Rated at 104 CFM, with 137" water lift drawing 12.5A?

Now THIS is a vacuum cleaner! And would suck the chrome off a trailer hitch. Since the intent is to use 2" hose to a hand tool over a relatively short distance I am thinking of a modification of the Thien separator that would make the separator tall enough to replace the body of the shop vac, do just enough filtration so the vacuum impeller did not clog and then exhaust into my central dust system where only 105 CFM would not be all that disruptive. Is this mad scientist or is there something to pursue here?

Peter,

What is the design of your separator inside the square box on top? Are you using some sheet metal or hardboard to round it internally or is square?

This is exactly what I want to build and I was wondering if there is some thought on the internal volume of the separator relative to static pressure/cfm. Then there is the issue of how to dimension the volume. The design seems to be incredible forgiving and people seem to design based on the size of the bucket and fittings they will be using. But x cubic inches of volume can be wide and short or skinny and tall. I have not seen the issue of volume relative to the static pressure/CFM digging through the archives or on the web. The slot size and percentage of the baffle to circumference has been discussed so I keep thinking I must be missing something.

It really is fun. As critters go, a big part of our success (and potential for demise) is our tool building proclivity.

So, I think you are right and I should find the gnarliest shop vac I can find and use a separator between it and the tool. So I will get off the idea of using the HF blower that I only use when working outdoors and want to generally direct the chips from a table saw to the garden and not all over the driveway.

What size hats work best with 50 to 60 inches of static pressure and less than 200 CFM? Or do I just buy one of those converted plastic milk jugs made by Oneida?

I had not thought of a CO detector and will get one soon. I am in the temperate South and even in winter opening the garage door a few inches across its expanse has always seemed fine for someone who vents outdoors. But a CO monitor is a very good investment to have mounted near the gas furnace that shares my garage shop.

Thanks

I would like to build a Thien separator optimized for power hand tools like a router, planer, belt sander, etc. There is no good option for making the discharge ports larger on these tools and besides it would make the hand tool a lot harder to use with some ginormous duct attached to it. I have a couple options for my routers. One is the factory inset that uses a 1.5" discharge outlet and the other is a homebuilt base extender that goes right into a 4" duct that resemble a large soup can screwed to the base of the router with a cut out for the edge I am routing. But most of these tools have to discharge up rather than down, through a 1.5" or so outlet.

I have used shop vac's connected to these tools but thought I could build a small tag along unit that was purposed for these tools and powered with a Harbor Freight 1hp blower that is collecting dust (on a shelf unused).

My question is this. Because I want maximum static pressure and the HF blower is rated at 914CFM (no mention of static pressure) I am unsure of the optimal dimensions for the top hat. I would imagine that I would just mount the blower up top and center with its 4" inlet dropping into the hat.

There are two major design questions. Well, three, but the third has been answered persuasively by Retired and a rectangular inlet is both appealing and the way I will go. The remaining questions have to do with the dimension of the hat in terms of diameter and height. The other question has to do with the question of inlet port size. The easiest would be to use 1.5" duct from the hat to the tool. Then again maybe it would be better to use 4" duct to a "half way" point and then use a PVC reducer that goes from 4" to 1.5" closer to the tool. But, because there are any number of trade offs and 7ways till Sunday to choose, I am looking for factual help in optimizing static pressure and collection for these hand tools. I will exhaust through a filter, to be decided later, that will maximize capture of fines and minimize back pressure, all compromises to be sure. But first I would like to tackle the front end. I will save my hind end for later where I end up showing it on a regular basis.

You sir are the voice of reason.

The fact is that there is no run over 20 feet to a machine should put capacity concerns to rest. There will be an 8" main with 3 wyes coming off it and reducing to 6" runs down to the machines. An 8" short elbow is still silly large to a guy used to 4" and 6" fittings. The blower was surplus and rusted through in places. I did not think the duct tape patches were all that attractive so I took the whole shebang apart and took the 5hp Baldor motor to a shop this morning for a once over and any maintenance it might be due for. The capacitor was looking a bit leaky and while everything is in disarray in the shop it made sense to just take care of this. I will get some sheet metal and Bondo the blower this weekend. My other project is installing a 6" riser on my 14" band saw. I also sprung for a new spring so I can tension the blade and get down to mitering up some PVC for proper 2x radius 6" elbows. I will see what room I have and I may be able to do better than a short 90 degree elbow for the top hat discharge to the blower. Heating and bending pipe over 4" is pretty hard to do effectively so it is going to be puzzle pieces time as I cut and plastic weld up my new fittings. Speaking of fitting, I found the band saw gong show recordings on this website, thank you Phil, and plan to experiment with them as I tension the new blades I will have to purchase. I went to a plastics fabricator shop last week and spent some time with a fellow who has been fabricating fittings and systems for 30 years. He has a monster band saw that he uses to cut PVC pipe and he has found that the 14-18 tpi bi-metal skip blades do the best job for the thin pipe. He uses 6tpi blades for the Schedule 80 and beyond stuff.

Ok, if I can't go up, maybe I can go down.

I am using 8" duct and my top hat will likely be built into the cut down bottom of a 55gallon heavy plastic drum. So it will be about 24" in diameter with the height to be determined by how I build the outlet which can't go up or if it goes up it will be a sharp 90 degree elbow fitting to the blower. Using the drum will save the effort of building the top hat surround. All I will need to do is build the slotted and fitted bottom and attach the plastic top. The inlet will be mounted into the plastic hat and enter  just as it is done in a Pentz cyclone. I may even go rectangular on the inlet, we will see.

At first I thought that creating a plenum the same diameter of the top hat would be a good idea. I would just build a mdf top layer mounted above my slotted bottom and insert the whole unit into the plastic surround. My thinking was that the vertical outlet that pulls from the center of the separator would terminate at the bottom of this top dividing mdf internal piece creating a top area or plenum. Then a separate horizontal outlet would pull from this 8"x24" space and exit the side going directly to the blower inlet with no joints or bends.

I was thinking that perhaps the large diameter space in the plenum area that drew from the center of the separator would create less resistance and turbulence in the outlet from the plenum to the blower than a sharp 90degree bend from the vertical outlet of the top hat separator to the blower. While I see that I am introducing more volume I still don't see why pulling from this large plenum would not be an improvement over the dynamics of turbulence and resistance that a sharp 90 elbow would make. But my reading of the feedback is that I have not solved the problem of a sharp 90 elbow with a large diameter plenum, even with a bell mouth outlet inside the plenum and a straight run into the blower intake. But it is hard to shake this idea, it seems to work in thought, at least.

So, how about going down?

What about a 2x long radius 90 degree elbow that starts in the center of the separator, goes down through the bottom of the baffle and then out the side of the dust bin below? Dust and chips would fill in around and above the duct but since unlike the bin of a cyclone where there is dynamic tornado continuing and such a duct would interfere, the dust in the bin of a Thien separator is supposed to stay still, down, and out of the suction of the blower.

This thing is going to be hugging the floor joists and I have under 5 feet to the bench below (with concrete below the bench) to make 8" duct work. I am not looking for innovation or challenge, just a remedy.

That is enormously helpful. I really did not understand the dynamics of how this worked. I proposed a layer that detracts from the performance of the original design.

The context is that I am aghast at the tables that show the equivalent feet of duct that a 90degree fitting adds to a system. Thanks for you clarifications and clear thinking. I am back to the drawing boards.

I was thinking about a plenum but then it became a bit more dynamic as I thought about its function.

The Thien innovation is the slotted baffle that keeps the turbulence separate from the chips in the bottom of the bin.

What if the top of the separator had a mirrored baffle. This would make the center between the baffle a clear space and rather than merely a flat plenum over a center hole of the top of the separator, one would have a horizontal outlet from the top half of the separator.

My thoughts are that if I merely had the outlet exit from the side it might pull up some of the dust racing around the walls, hence the top baffle.

But if this makes no incremental difference then the vertical tube in the center is the eye of the storm and the cleanest place to get air out of the separator.

One additional question. How was the height of the "hat" defined. Was this empirical or is there some relationship between the CFM and the height of the "hat"?

I have found one post where Phil discouraged using a horizontal outlet unless it was "off center", I don't understand what this means or where off center would be horizontally. I may have that wrong but my question is this. It seems that the main work done by the separator is accomplished by the lower baffle/slot and that without much ado debris sinks fast to the bottom through the slot in the baffle and stays put because it is protected from the turbulent spin at the top and doesn't get stirred up again to travel past the new material that is coming in, around and down.

I don't understand the dynamics of this enough to know why a horizontal exit on the opposite side of the inlet raised a above the inlet, at the same essential height of the vertical inlet as designed would not be as or more effective than a vertical outlet that then requires a elbow to a horizontal blower. All resulting in more needed head room and vertical space to fit the unit.

I am vertically challenged and am right at my joists for the top of the separator and it would really help to have it side discharged. Also I while I see that taking the outlet tube into the middle of the separator hat if low would disrupt the spin of the inlet, I wonder if just making it higher would get it out of the way. I guess I don't see how a vertical outlet in the center versus horizontal outlet at the same height would cause more debris to go to out the top. That is unless is grabbed material rotating on the wall and pulled it out before it settled below the baffle. Perhaps this could be fixed by having a top baffle that mirrored the bottom baffle only on the opposite side so that the the inlet and out let were opposite one another and the baffle slots were also opposite each other. I am using 8" duct and a large salvaged commercial blower. I would like to avoid requiring more room at the top. Making the top tall enough for two 8" ducts is already going to create a pretty tall hat. I may try this as an experiment unless there is some dumb gotcha that I am more than capable of missing.

Shop vacs put up big numbers in terms of static pressure and low numbers of CFM.

Underpowered commercial dust collectors put up larger CFM and modest static pressure.

In my particular situation I am trying to get the best performance out of an old ShopSmith DC3300 Dust Collector that I have taken out of moth balls with my shop being reconfigured but still needing to have some head fake towards dust collection to rebuild the shop after my conversion experience to sliding table saws.

This is an underpowered but very elegant dinosaur that "boasts" 1/2 HP and 330 CFM. While I rebuild everything in the shop to accommodate my new religion I will have to rely on it or some combination of shop vacs. I am trying to decide whether to drop a modest $40 on a Dust Deputy that is nothing more than a large sports bottle with 2" fittings or put a Thien style collector in the bottom of the ShopSmth unit ahead of the intake. I would go for the Dust Deputy if it handled the fine dust better than the native DC3300 but have my doubts given its dwarfism and what looks like a reliance on static pressure to get it to perform. There is a Hopkins study published on the Clearvue min unit that suggests efficacy but again I think it relies on high static pressure to work well.

I would build a Thien separator that would sit in the bottom of the DC3300 if static pressure was key to these midget cyclones being successful at what they do. I have a full size Wizard of Oz sheet metal cyclone and a 5hp New York 18" blower that is not currently in commission due to the regime change.

The internals of the DC3300 make this single stage dust collector non amenable to putting a Thien style separator in the middle of the machine because that is where the blower itself lives. So there will have to be something that sits "ahead" or under the single stage unit. This will likely mean a can sitting under the bag or rather shortened plastic bag at the bottom of the DC3300.

So will the ShopSmith with its unknown static pressure but published CFM of 330 and all of 1/2HP do better with a Thien separator or a midget cyclone. My fate is in your collective hands.

I have looked but have not found a way to calculate the loss of cfm and static pressure for a given volume of container. What, for instance is the loss of cfm/static pressure in a 30 gallon or a 5 gallon, etc, container?


I also wonder if there is a difference in the ratio of height to diameter in the efficiency of dust collection which is a different question, but one which would rely on a knowledge of the "cost" in static pressure introduced by a given volume of container. At what point is the convenience of a large container reducing the effectiveness of the separator?

And would the shape matter. Is there a difference in a tall and slender container versus a short and squat container that relates to efficiency of dust collection or in relation to cost in cfm/static pressure?