J. Phil Thien's Projects

Retired -
The size of the waste can is more a function of convenience rather than performance... 

It depends on what you expect your usage to be. 
On my shapers which run for several hours each day, I have 20 or 26 gallon 'Brutes'.  Some get dumped once, some twice each day.  The generate a lot of waste and I want the small can to get dumped regularly. 

I have a cut-off saw that gets minimal, infrequent use.  I have a 55 gallon drum for it because nobody wants to spend 10 minutes emptying it when they only made two cuts.  So we avoid it for as long as possible... 

In a production environment, I want it to be either so easy and convenient that it happens without interrupting the workflow, or, I want to postpone it as long as possible. 

For a hobbyist, I think it depends on one's personality.  At one extreme, a neat-freak can use smaller containers because they will get dumped after every task - or at least daily.    At the other extreme, a procrastinator will want large containers.  Out-of-site, out-of-mind until it is absolutely necessary.   

Before building a separator, were you inclined to keep you shop neat and clean after every project?  Or, were someone you just wanted the debris out of your way so you could get your work done?  NO moral judgement here - both extremes produce work to be proud of.  Most of us are somewhere in between - this will just give you an idea of how you will actually use your separator and what the 'dump-cycle' will likely be. 

Hope this helps!
Jim

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I'm going to build mine with the conventional shape.  I'm still thinking about a rectangular entry port, but I'm not sure I want to spend the money to have a custom transition piece fabricated.

Don -
After spending too many years fabricating sheet metal on job sites, here are some suggestions for a 'Poor Man's' transition... 

For purposes of simplicity, I am going to assume that your rectangle 5"x4" and your round duct is 6".   

Home Depot and other 'big box' stores sell 6>7" round transitions for a few bucks. 

Make a layout sheet on paper/cardboard and draw your 5x4 rectangle.
Draw diagonal lines and extend them a few inches past the opposite corners. 
Use the intersection of the diagonals to draw a 7" circle. 
Center the transition on the circle and mark the diagonal lines onto the transition. 
Copy those marks onto the inside of the transition. 
Take a sheet of plywood or MDF (at least 1/2" thick) and cut out an interior rectangle that is 5"x4". 
Get a stiff laminate sheet or Masonite or equivalent that is less than 1/8" thick. 
Cut the thin sheet into an isosceles triangle that is not as tall as the transition and is at least 7" across the base. 
Drop the rectangular cut-out over the transition as far as is will go and remain perpendicular to the cone.  This is your outer form. 
Align the triangle wedge with the interior marks and push it in snugly tight.  This is your inside form. 
With the wedge snugly in place, push down a little farther on the exterior form (maybe 1/4"). 
Remove the wedge and rotate it to the other diagonal corners.  Press it in snugly and press down on the exterior form. 
Keep rotating the wedge and pressing the exterior form.  If you start pushing too hard or too far at one time, the shape will twist or warp. 
When you get near the final dimension, the metal will nearly fill the corners.  Use a chisel and tap it into a sharp corner. 

Be sure the outer form is square to the transition and draw a line around the top and bottom edge of the form.  Remove the form and use shears to trim on the outer/bottom line to get a finished, rectangular edge.  At each diagonal/corner line, slit the diagonal up to the inner line.  These 'flaps' can be screwed or attached to your the rectangular opening of your Top Hat.

Hope this helps!
Jim

Oz... 
Venting to the outside is certainly a viable option.   However there are a few things to consider. if none are applicable, then it is your best solution... 

1) Legal.  While a private homeowner can open his garage door and spread his dust and chips to the atmosphere, few municipalities allow a commercial business to do so.  The SCAQMD (Los Angeles), requires a permit for ANY duct that exits a building (even passive chimney hoods).  It MUST be filtered, and you must document any emissions or contaminants contained in the exhaust.  Since California has Prop 65 which requires disclosure of any materials which containing carcinogens and most hardwoods will give you cancer if you eat over 12 boardfeet a day, you are technically spewing cancer to the community.  Fortunately, there are only a few isolated cases of enforcing these laws, but it is coming... 

2) Good neighbors.  That exhaust duct will also emit sound as well as air.  How close is your neighbor's bedroom window?  Or, your sleeping infant? 

3) Winter's are cold (even in SoCal).  For every CFM you exhaust, another CFM has to enter your workspace.  If you are conscious of the cost of heating or cooling your workshop, your utility money is blowing out the duct.  With a 600cfm blower, a 20x20x10' workshop gets the air replaced every 6.5 minutes.   

4) Ooops!  The Thien Separator works so well, you tend to forget it.  I assume that most of us have let their separator overflow at some time or another.  When that happens, 100% of your debris goes out the exhaust.  Will that become mulch in your flowers?  Or, did you just spray your neighbor's driveway?  (with his new Harley parked downwind...) 

If none of these factors come into play, then count yourself as one of the fortunate few who have a system that is simpler and cheaper to run than most! 

Hope this helps!
Jim

To add on to Bill's comments... 

Having spend much of my manufacturing career in sheet metal fabrication, I learned a few simple lessons (in some very hard ways). 

As long as you only have to fabricate parts in one plane at a time, there may be many steps, but each one is relatively simple and economical.  Example: Pipe bending - It is not much different or costly to make a 30/45/60 or 90 degree bend.  Making a series of bends is just a series of successive, repetitive steps. 

Making changes in two planes gets to be more complicated, but is still definable steps.  Example:  Folding a box and lid (like a shoebox) - The box is taller and the lid is larger( to cover the box), but each has the same number of steps.  If it is 6" or 16" the work is still pretty much the same. 

However, when you need to make changes in three dimensions simultaneously, it has to be physically mocked up to determine production tolerances  - or in today's world, it is modeled by computer.  To actually fabricate parts with three dimensional changes is orders of magnitude more difficult both in the costs of design and development and in the equipment required to produce it.   

Shark Guards are a prime example of taking a sophisticated application and reduce it to simple, profitable (I hope) production.  I am sure that there was a lot of head-scratching and hair-pulling to come to his actual production model. 

As far as your steering wheel goes, you have to determine the price the market will bear...  At $400, it probably won't sell at PEP Boys, but marketed through car-clubs, it may go  for $500.  How much effort will you go through to earn $4-500?  If you can't reduce the effort and investment to your satisfaction - you found out - it isn't worthwhile... 

Fortunately, most of us are doing it for the personal satisfaction and admiration of those who matter to us.  If it was supposed to be financially profitable, it probably wouldn't be as fun...

Enjoy!
Jim

Bill -
I hate to nitpick or sound negative, but I have a few more questions...

Quote from: bill70j on June 29, 2011, 04:10:40 AM
You are correct.  The cyclone suction drawings and separation results I show in the earlier post are reflective of industrial cyclones operating downstream of blowers in a low positive pressure environment, rather than small cyclones in vacuum service like the separators discussed on this forum.  

I am not aware of any cyclones or other separators that are 'downstream' of blowers.  Generally, you want to remove all the waste in the airstream before it gets to the blower impeller.  In all designs I am aware of, the only thing that is downstream of blowers is 'bags' or 'filters' and they do not want to see the debris that is trying to be separated - let alone have it go through the blower..   

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I will do some digging around and see if I can find the pilot plant data that went into the design of the inlet scroll feature.

One thing that occurred to me after my last post was that it appears you are using the 'scroll feature' on the inlet side of the airflow.  As I look at all the blowers I have on my ventilation, HVAC and dust collection systems, the scroll is all on the outlet sides of the blowers.

If you can dig up that information, it will be interesting to see if we can scale it down 2000:1 for the small systems we are using in our shops. 

Hope this helps!
Jim

Bill -
Has this design been compared to a 'traditional', side inlet top-hat design? 
Have any consistent measurements been made? 

I would be very interested in knowing these results.  I am not aware of scroll designs being implemented on the suction side of the system.  They have been in use in blower designs for at least 75 years.  It is a proven way to simultaneously increase both velocity and pressure within the blower housing.  But I have some questions about their effectiveness on the suction side...  Some empirical measurements will be quite enlightening! 

Also, are the data listed in your first image based on the dimensions listed?  That is a HUGE design.  I am not certain how much air would be needed to make a 4' diameter separator work effectively.  I have a 10hp, 4000cfm system and I know it could not drive a 4' diameter Thien separator... 

My largest separator is 24" but all new ones are <16".   I have a 12" unit that separates MDF fines down to <3 microns - sampling shows NO particles 3 microns and larger.  On that unit I paid an extreme amount of detail to edges and corners. 

I will look forward to any measurements that Bill can provide. 

- Jim

I think you are on the right track with your ideas - keep going and you will come up with a clean, simple design that will work extremely well. 

I would double check one thing about your blower motor...
Sometimes, economy motors save costs by using bearings that are only designed to work in one axis (horizontal, shaft up or shaft down).  With smaller horsepower motors, most can operate 'universally'.  In larger motors, the cost of the bearings and unique motor designs become more specific in their orientation.  Since your blower is a 'stand-alone', special purpose design, it may be worth checking out.  If you have the data sheet on the motor, it may list the numbers used on the shaft and end bearings.  A quick call to a motor repair shop can confirm if the bearings can run 'shaft down'... 

As far as the RubberMaid trash can goes, I have had great success using the 'Brutes'.  My first design used the can's snap lid for the top.  I cut though it for the ports and glued PVC fittings together on top & bottom (I got 4" 'street elbows' with male/female ends).  I glued them together, sandwiching the lid to dog-leg them as the inlet port.  Two 5" couplings sandwiched the outlet port.   (This offsets the suction loss presented by the baffle.)  I had the baffle seal onto the 'step-ledge' below the handles. 

This works well - with two drawbacks:  1) To dump the can you have to raise the baffle up about 6" to clear the can.  This means you have to maintain enough hose on both ports to raise it that high.  2) Getting great separation on a 32 gallon can means moving a LOT of air.  I have to pull almost 1000 cfm through it for it to work to its optimum  It works 'OK' with 650+cfm.  Since I have it connected to a 4000cfm Dustek unit, that isn't a big problem as long as I don't have too many other tools running - but often we do...

My recommendation is to make a smaller 'Top-Hat' that mounts to the RubberMaid lid.  The plastic lid gives you a durable, flexible seal and you can build a smaller diameter that will work much more effectively.  Dumping the can only requires 1.5" of clearance to remove. 

I think the idea of mounting the blower to the wall is a great one.  You can limit the amount of flex between the top hat and blower to give you just the clearance you need to remove the can.  Some cable or even 'bungees' provides the support to hold up the top-hat while you wheel can outside to dump.  Adapting the Wynn filter will capture the fines to keep you shop clean and safe to breathe in. 

Let us know how it turns out!

Painterman -
I sympathize with your decision. 
My commercial woodshop started using separators because our large, multi-bag dust collectors are upstairs and a very inconvenient to clean and dump.  (Out of sight, out of mind and everyone will avoid the 'dirty work') 

By using the separators (between the machines and trunk lines), we keep the waste on the floor in 'Brute' cans on wheels - nobody complains about dumping them. 

However, we do have suction losses.  Our measurements are not as severe, though.  Using a manometer, we measure about 1.5" of suction loss.  This adds up with several separators connected.  We have the trade-off that the overall system flow is reduced, but since it has very little waste in the air stream, we can tolerate the reduced air flow. 

The losses you are describing seem much greater than normal.  I am wondering if there is something that you have overlooked in the design or something else that is compromising your performance?  Your empirical measurement of sticking your hand over the hose should detect reduced suction after the separator, but not to the level you describe... 

I hope you get this solved.  Using the separator is a MUCH, MUCH better way to work rather than dealing with bags! 

- Jim

I had a previous installation where the cyclone was tucked in the corner and was a nuisance mover things to get to it to empty...  Using the Separator ahead of it allowed me to keep the waste near the machines and more convenient access for dumping. 

There was a trade-off in drawing 'through' the separators - they presented a small but noticeable load on the cyclone system.  But since the system only had a tiny fraction of the waste (and it was only the remaining fines), it seemed to work better - but we never tested/measured performance. 

Hope this helps!

Bulldog -
I am off for a few days, so I will try to remember to take some pics when I get back... 
Most of the separators are attached to our 10 and 25 hp units. 

We started with placing baffles inside the 'Brute' trash cans.  We just cut holes through their snap-on lids.  The baffle is set to the height of the 'step-in' at the handles.  Our baffles are made of 1/4" Baltic Birch plywood (because we use a lot of it and have it around).   

Those big cans work 'OK', but our 4" hose lines run ~450 cfm which is not enough to generate good cyclonic action.  It is acceptable for some of our cut-off saws which have mainly chips with little dust.  Our 5" lines pull almost 900 cfm and those work much better. 

For some of the sanders, we cut out the bottom of a 5 gal paint bucket, leaving about a 3/4 lip around the bottom.  We then cut a matching hole in another top of a 'Brute' trash can.  A little bit of sealant, some rivets with washers and we have a smaller, faster separator with big waste capacity... 

Our 'first generation' separators were quick and dirty to prove the concept and test their effectiveness.  While attaching the baffles to the trash can lids worked very quickly, they are awkward because you have to lift the entire baffle assembly up out of the can to be able to empty it.  We are in the process of creating replacement 'top hats' that only have to raised 1" to get the barrel out for dumping.  We will even test one that is 'hard-plumbed' to our dust collector - eliminating flex hose.  So we expect even better performance!


STEVE -
You are just going to get a lot better collection than you need to have.  It is not a bad thing - just more than you think you need... 
If you place a 'grate' in the bottom of your separator (perforated or expanded metal or similar), you can let the finer dust settle to the bottom and keep the 'chunks' above.  Then, you have some great mulch filler for your flower beds or planters... 

Enjoy!

Container size has two factors:  Separator size and waste collector size. 

Smaller sized separators separate finer dust.  Larger collectors hold more waste. 

I have a number of machines in my shop (commercial woodworking) and we have a variety of solutions. 

Typically, I don't want to waste much time dumping sawdust, so I try to size the containers to handle 4 hours of continuous production.  Worst case, they have to stop and dump twice a day...

For sanders which generate only fines - we use separators made in 5 gallon paint buckets.  For planers and jointers which generate heavier chips, our separators are in 44 gallon Brute trash cans.    Many of these are attached to 10 & 25 hp bag-style dust collectors - which rarely get much material from the separators...

Some of our sanding machines run all day and generate a lot of dust.  These have a 5 gallon bucket mounted over a 55 gallon drum.  They separate the fines - but drop them into a big container that gets emptied every day. 

I also have some large chop saws which only make 3-4 cuts in an hour.  Those have vacuums which start quickly and suck enough for the large chip/small volume debris.

FYI:  My main trunk line is 12".  Most drops are 7".  Then, I split down to 5" & 4" to fit to machines... 

So far, I am running everything wide open to keep the velocity high in the trunk line.  If I add more than one more shaper, I may have to start using blast gates on a few end runs...

But for now, my trunk line velocity remains above 4000fpm - so everything stays clear...

Bulldog -
I agree that your 'side inlet' design provides the least obstruction for incoming debris and maximizes the area for separating particles from the airstream.  This is the way cyclones are designed.  Bill Pentz's research and designs have a neutral vane that extends into the cyclone to improve rotational airflow.  Since cyclones use a larger vertical height and the debris spirals down, that neutral vane doesn't see the same air/debris coming past it again... 

Since a wide variety of inlet configurations exist and most seem to achieve very good results, it does not seem to be a critical factor in success.  Since most of the 'baffle-builders' are hobbyists and not commercial shops, I suspect that the difference between 90% effectiveness to 95% or from 95 to 98% is not important.  It is the 0-90% improvement that has helped us. 

When commercial shops begin using more Thien devices, then I think that the 'science' of what works best will become better known and developed.    For them, they have two driving factors:  Power efficiency - the 5% savings of running 10, 20 or 50hp motors for a whole shift becomes significant.  Air Quality - when OSHA requires the shop air to improve and you are facing everyone switching from dust masks for full respirators.  These issues become driving factors to squeeze the most effectiveness and will justify the detailed testing to determine what works 'slightly better'... 

Looking forward to what happens next!
- Jim

Steve -
I am afraid that the leaf blower is just not big enough to move enough air to make the system work is good as it could... 

I placed a lid on a 30 gal 'Brute' trash can to use it with my table saw.  It is nice having the 30 gallon capacity, but it doesn't separate is nicely as a smaller diameter 5 gallon bucket.  My ideal solution is to cut the bottom from the bucket and place it over the 30 gallon container.  I get the better separation plus the higher capacity.  My only drawback is the increased height gets in the way... 

Collecting your leaves creates a lot of volume, so you want the large container.  But you need a smaller cyclone that will work well at lower cfm...  Perhaps the next time you need to clear your roof you could try putting the smaller can on top.  For a leaf blower, I would try a 2-3 gall container. 

Question:  Are the leaves dry or wet?  From your desert clime, I assume that the leaves are dry - so they should pick up easy and crumble into smaller particles.  If they are wet, you will probably have a problem with them sticking to everything...  Unless they clog the hoses, the cyclone won't care.  I have vacuumed lots of wet debris through the cyclone.  It makes a mess, but if it will dry without turning to paste, it seems to clean/clear itself with more use. 

I will look forward to the pictures!

I know - it seems counter-intuitive... 

When the system seems to 'scream' because it is starved for air, the motor is not working hard.  When the system is 'wide open' and gulping in large amounts of air, the motor is heavily loaded. 

That is why most DC units that we buy have been designed to prevent this.  Even if you remove the intake duct, the cover plate of the housing still provides restriction.  The outlet port of the blower also defines the max throughput.  Slightly less performance means a longer 'happy-life' for the blower motors. 

Let us know how your system works when you get it installed - I think it will be a good installation!