Thread: Wheelie Bin Cyclone?.

Ah the many pitfalls of combining blowers.

Originally Posted by doug3030

All you are doing is running two separate impellers into the one collection bag. What does that achieve?

and that's just the first of 3 problems

The second is the that square section curly Y junction has narrower arms than the base so the flow out of each blower will be throttled by the arms

The third is the killer and that is that a substantial component of both air flows will be slamming against each other so the back pressure will be very significant are reduce the flow.

That big Y connector on those DC is basically a 1950's mongrel design and the blowers are also of the same vintage. Like most DC impellers they design is not even a true spiral so they have a linited back . Not that I'm saying that everything from the 50's was a dog

Also to get the benefit of any larger flow you will now have to run two independent lines back to every machine. Coupling the two impellers up to a larger duct and sending the larger diam duct back to the collection point is wasted because of the 3 points above.

The best thing that can usually be done with two old school 3HP DCs is to use them in stock form (OK maybe convert them to 6" ducting), strategically locating them on opposite sides of and outside a shed and connecting them up to different machines simply to reduce duct run length.

One thing that most people do not understand that cheap 4 x 1HP or 2 x 2HP motors with small impellers, will simply not add up to a decent 4HP motor/blower.
This has to do with the physical size limitation of the inlets and outlets, impeller designs and the flow rates possible under back pressure.

The usual flow rates that we throw around are unrestricted flow rates (CFM) but the added back pressure from cyclones, filters/bags, ducting, junctions and a real world machine pathways and small DCs will basically choke very quickly. This is again why BP uses a 4HP motor and a 15" impeller. When the sawdust coming off a thicknesser starts to come off in large volumes the bigger motor/impeller makes a big difference.

The second is the that square section curly Y junction has narrower arms than the base so the flow out of each blower will be throttled by the arms

So if I am making my own Y duct to co locate the blowers, (above and below - i.e. inlets facing each other to similarly join into one larger duct) then can't that "throttling" - be overcome just by increasing/reversing the dimensions of them?

The Photos just to give the idea of combining 2 smaller (cheaper) impellers, to get double the suction / blow rather than the expense of the larger BP impeller and engine AND keep all that weight down at ground level (or below fence height) for service / maintenance and stability / noise / visual reasons.

The third is the killer and that is that a substantial component of both air flows will be slamming against each other so the back pressure will be very significant are reduce the flow.

I start with 6 HP.... while BP starts with 4.... and the slamming of air / back pressure will drop me below BP's CFM figures?

Can I remind you that the figures published for the 3 HP Carbatec Cyclone are are some 600 cfm above BP's published / claimed CFM rates.... and they do it with just 3Hp. (i.e. 1935 @ 8 Inch for CVM, versus 2500 for Carbatec...) so to me at last it looks a LOT like BP's 16 inch impeller and 4HP engine isn't that efficient if a 3HP model out performs it by ~25% in CFM rates.... Maybe the CVM has some air slamming issues of its own going on inside the fancy clear plastic.

Hey I'm just quoting the published numbers, I'm sure there will be all sorts of fudge factors in there & maybe the Carbatec ones are out of China and the air flow fluid dynamics guy had a dodgy bead on his abacus....they day he measured and calculated his flow rates.

I can only go on whats published and on paper at least (or the electrons of the intranet) the CVM comes in a poor second to the Carbatec in price, build, & performance.

What can I say, on paper it sucks - but not like Monika Lewinski it would seem.

Without running testing gear over the CVM & Carbatec units side by side... how do we know - who's sucks most.

Similarly coupling 2 smaller ones together - until its done and we measure it aren't we all just guessing?

At the moment I can't find anyone in WA with a CVM to even go view running.... so i have to take everything at face value based on whats published by the manufacturers.

I'm no fluid dynamics expert... so what else have I to go on than whats published?.

At the published data - CVM is incomplete (doesnt come with a self supporting frame to even stand on it's own 2 legs so to speak, its wastefull of HP and thus more expensive to run... according to published CFM and HP rates.

I'm just stating what the published data shows me.

I can buy the Carbatec at Ossie Park - versus importing a CVM thru an agent in the east... who imports it from the USA (And our pacific peso is dropping like a rock against the greenback at the moment).

I'm just not getting the warm and fuzzies from the CVM product yet Bob is all.

Apparently neither is anyone else in W.A.

Lets just say thus far despite the excellent work done by BP - that in terms of bringing a product to market, I am left underwhelmed.

That could change - CVM might step up and further refine their product in due course - make it self standing and enclosed in some kind of weather proof cabinet, maybe even look at sawdust handling after collection - who knows.

Thus far they seem to be more intent on not listening to potential customers... and defending what they already have - an assemble it yourself kit that costs more than the commercially made product.

I'm just calling it as I see it at this moment in time Bob. Your comments & suggestions are being taken on-board (even if it may seem other wise) because they make sense, and could be incorporated into a final solution yet, possibly.

I'm surprised I guess, at the amount of interest in the whole dust extraction question.

By the time I get to dust extraction solution for myself - at the very least i will have explored it in depth from every angle, and be confident in my outcome before I start.

$2.5K+ (plus ducting) for me is a big investment - but so is my health (and not just my lungs) so I tend to look at all aspects of the dust handling equation. heck my shoulder twinges just typing at the keyboard - humping large metal tins full of saw dust around would finish me off.

I know I can manage to wheel a wheelie bin to the curb, I do a couple every week... so that's why that aspects so important to me.

If I was 25 again and could lift that much weight on the end of my Johnston - then the sawdust handling issue wouldnt be such a sticking point most likely. I've learned the hard way that the hard way isn't always the best / easiest way.

I can't see the point paying a lot of $ in gear and power - collecting and sucking all that weight of sawdust up to the roof of the factory/shed to then deposit it back in a tin on the ground that no one can lift - that's just bad / lazy design - lift it once and keep it up there for easy disposal, or at least put it on wheels so it can be moved easily for disposal. To me that's just common sense born of age & cunning.

I guess maybe I ask too much.

Doug thutty thutty / Doug the slug.

Thanks for your link- very inspiring reading indeed.

I didn't want you to think I hadn't read and taken on board your much valued input!.

Yesterday when I went to read the link my net connection died as it does so often...

So today first thing I had a good read of your thread and the photos - very inspiring so thanks again for the heads up!

I am thinking that, it might just be possible, to cut and reduce one of those blue plastic 200 liter drums from the rural feed stores, to make the requisite cone diameter and length (1.64 times diameter) and join say half a blue drum on top as the cylinder and hopefully get a cylinder and cone of close to the same dimensions as the BP design.

I will have to measure one up... and see how close it gets to the BP specs & how it could best be cut to reduced to the appropriate cone.

That or find an appropriate cone (Large traffic cone?) or something else that can go on top of the wheelie bin.

I am even kicking the idea around of making the cylinder out of aluminium... I have a mates a naval architect who once supplied a plasma cut kit I built a 16 ft barra punt boat out of - and I reckon if I gave him a copy of BP's specs for the cone / cylinder - he could have a cylinder and cone plasma cut from alloy sheet, and then I just have to roll it into a cylinder and cone, weld them together, add the air ramp... and come up with a stand and clamping mechanism...for the wheelie bin receptacle.

All options to kick round, I'd like to do it in some kinda "cheap easily available product" like the blue plastic 200 liter drum if possible - just so others can duplicate it easily and cheaply - I want to try and stick with my ~ $500 budget.

If $ were no object, then likely there would be many different ways to approach this.

I have to keep the end budget figure in mind within whatever eventual solution I come up with.

Originally Posted by Timless Timber

I will have to measure one up... and see how close it gets to the BP specs & how it could best be cut to reduced to the appropriate cone.

As I recall it, Bill P specifies a larger diameter drum for 2hp than for 3hp impellers. For the 2hp it was as close as made no difference to my steel 44's. The plastic drums are a bit smaller, I think from when I did my research but that was a long time ago now.

It might be possible to make a cyclone in one of those plastic drums and make some sort of interface to make it fit airtight onto a wheely bin.

Doug

Originally Posted by Timless Timber

I start with 6 HP.... while BP starts with 4.... and the slamming of air / back pressure will drop me below BP's CFM figures?

Yep. One way to think of it is that two 6 cylinder Holdens welded together at 45º won't go faster than one V8.

Can I remind you that the figures published for the 3 HP Carbatec Cyclone are are some 600 cfm above BP's published / claimed CFM rates.... and they do it with just 3Hp. (i.e. 1935 @ 8 Inch for CVM, versus 2500 for Carbatec...) so to me at last it looks a LOT like BP's 16 inch impeller and 4HP engine isn't that efficient if a 3HP model out performs it by ~25% in CFM rates.

We've been through all this many times on this forum - basically all manufacturers quoted DC specs can be halved and that will be closer to the mark.
Look here https://www.woodworkforums.com/f200/r...ations-171558/

quoting the published numbers, I'm sure there will be all sorts of fudge factors in there & maybe the Carbatec ones are out of China and the air flow fluid dynamics guy had a dodgy bead on his abacus....they day he measured and calculated his flow rates.

Yep the fudge factor is x2.

The situation is actually even worse than the x2 because when it comes to the crunch its thje flow rate under load (or restriction) that really matters and that's when the extra horses and impeller size really count.

Without running testing gear over the CVM & Carbatec units side by side... how do we know - who's sucks most.

BP has done the flows rates on his design and while he may not be exact (who is?) I believe him over any chinese import figures.
I have measured a few generic DCs and apart from BP's data I only trust what I have measured.
I have contacted a number of people who have put up data on the net about flow rates and when I ask them how they did it they are all performing the measure they are all doing these incorrectly. They are either using the wrong type of measurement tools or techniques or both.

Similrly coupling 2 smaller ones together - until its done and we measure it aren't we all just guessing?

Not really, I haven't tried your exact arrangement but the one I used about 20 years ago was similar and I'm confident enough about the theory to make these

This brings me to yet another question if I may Bob.

In terms of measuring the suction I see figures quoted for standing column of water - measured with a manometer...

Would it be possible / easy to make a manometer that is connected say to the suction near the cyclone or blower or where ever its connected - out of say clear PVC tube - and graduate alongside it with a measuring rule/tape - such that when its turned on - or a blast gate opened / closed...or as the bin fills etc - one can tell at a glance how the unit as a whole is performing?

In my admittedly limited knowledge of this dust extraction subject (and manometers) - it seems to me that the suction just lifts a column of water against gravity until the weight of water, in the column it can lift no more...and that's the standing column measurement?

I was thinking that an arrangement of PVC hose with water as a measure of the suction in effect at any given time - might be a part of the build so that the effects of any tweaking / alterations become immediately obvious?.

Just a thought.

Are manometers more complex than I imagine?

A most interesting thread (and also Sturdee's link from one of the first posts). I am pleased to see that there are people on the Forums who can discuss at greater length than I. It takes a little of the heat off .

Can I make some comments. I going to anyway starting with the simple ones.

Disposal of sawdust: You can always take it to the tip yourself if you don't fancy using it as garden mulch (It does consume N2 in it's early life and so is counter productive in some regards) and your garbage collectors object to being subjected to possibly carcinogenic materials.

Myself, I used to put it on the garden, I have taken it to the tip, but now I give it to my neighbour who says the pigs on her fun farm just love it when she puts them in a trailer to go to the markets. If only those piggies knew what was in store for them.

Location of DC: I think it is generally accepted that the finest dust of all escapes and that is also the most dangerous. Consequently I plan to place mine in a separate sealed room when I build the new shed. If I didn't have the room I would put it outside. I do not want it inside the space I am working in, although that is what I have now.

Cyclones: What do they do? (Not how physics of how they do it). They take the load off the DC bags. This reduces the loss of airflow though bag clogging and so maintains DC efficiency for longer. They capture the bigger particles by a centrifugal action, throwing them out of the main airflow to be collected in a receptical (wheelie bin, 44gal drum, other garbage bin etc.). In good systems they capture in excess of 90% of the dust and reduce the amount of times the bags have to be emptied or cleaned.

Do we have to have a cyclone? Here comes the controversial comment. Could we just have a largish container with a simple inlet and outlet? Imagine a the ubiquitous 44gal drum. At the inlet and outlet airflow is significant, but in the middle there is relatively still air which will not keep dust in suspension. The result is that it drops to the bottom. Is this too simple?

I will tell you how I know this. I used to work at a power station which had electrostatic precipitators, which catch the flue gas from, in our case, boilers. Now when one of these "precips" was out of service, but the boiler was in sevice, we could gain entry. At the manhole door there were gale force winds (from lekage through dampers and huge fans, that would rip the hardhat from your head and cause your hair to stand out at 90 degs from your head. Once inside the "precip" the atmosphere was dead calm. You could have lit a match and the flame would have stood upright without flickering.

Possibly a cyclone is more efficient than a simple box. However the box has some advantages too. It's cheap (use what you've got), it doesn't impact on your system airflow and it doesn't require high ceilings. These were three objections to the cyclone concept outlined early on in the thread and to some extent perpetuated.

So have I tried any of this? Yes and No. As well as my DC (stand alone twin bag 3HP) I have a ducted vacuum system (well that's how the manufacturer envisaged it) hooked up to my SCMS with a garbage bin in between. Above the garbage bin is a 20L bucket which has a large funnel plumbed into it. No cyclone as such and now swirling of the airflow creating centrifugal effect.

What I can't really tell you is how this system works compared to a bare vacuum cleaner as I don't have access to BobL type gear. I will try and take some pix tomorrow just to give an idea of the setup. Then you just have to scale it up to a full blown dusty (sorry .)

I don't mind if I'm shouted down. Go for it.

Regards
Paul

Originally Posted by Timless Timber

This brings me to yet another question if I may Bob.

In terms of measuring the suction I see figures quoted for standing column of water - measured with a manometer...

Would it be possible / easy to make a manometer that is connected say to the suction near the cyclone or blower or where ever its connected - out of say clear PVC tube - and graduate alongside it with a measuring rule/tape - such that when its turned on - or a blast gate opened / closed...or as the bin fills etc - one can tell at a glance how the unit is a whole is performing?

In my admittedly limited knowledge of this dust extraction subject (and manometers) - it seems to me that the suction just lifts a column of water against gravity until the weight of water, in the column it can lift no more...and that's the standing column measurement?

I was thinking that an arrangement of PVC hose with water as a measure of the suction in effect at any given time - might be a part of the build so that any tweaking / alterations become immediately obvious?.

Just a thought.

Are manometers more complex than I imagine?

Yes and no. The only real measurement you can get from this sort of manometer is what is called a static or no flow pressure reading. This pressure will give you an indication of what the MAX airflow will be in a system and are also useful for testing leaks but that they will not measure actual flows unless they are calibrated and used in conjunction with a pitot tube and a complex measurement protocol is used.

Have a read of all of this thread (https://www.woodworkforums.com/f200/f...roject-173794/) and by the time you get to post 32 which briefly explains what is needed to do the measurements and then you will get an idea of what is involved.

Alternatively you can read the BP version here
Bill's Cyclone Dust Collection Research - Measurement

Thanks heaps guys - we keep accumulating more and more detail. (I guess it's maybe been posted before).



Not quite as large as I'd like, but at not much over $100 delivered - it's getting closer with 2 inch and 4 inch inlet outlets.

Surely to goodness someone makes something commercially suited to using with a normal 3 Hp dusty?

There's a few that suit shop vacs with 2 inch hoses... but nothing that's made for 4 inch ducted shop dusty's!

I am thinking even a pair of 60 liter thinners drums... one cut down into the cyclone and 2/3rds of one as the cylinder top half with air ramp....should about match the size / impeller and HP of a 3HP dusty.... plus the wheelie bin collector.

The bottom out of one of the drums could be made into the air ramp maybe... (already the right diameter)

Off to read Bobs links.

Originally Posted by Timless Timber

- it's getting closer with 2 inch and 4 inch inlet outlets.
Surely to goodness someone makes something commercially suited to using with a normal 3 Hp dusty?
There's a few that suit shop vacs with 2 inch hoses... but nothing that's made for 4 inch ducted shop dusty's!

Any DC that uses only 4" is limited to ~400 cfm add a standard cyclone and you'll be down to ~300 cfm i.e. pretty hopeless, 2" is even worse.

A few piccys to illustrate what I was talking about in my earlier post. The general idea was to use this system for the SCMS and any other hand held tools such as routers and planners. To that purpose the piping has two additional lines to opposite parts of the shed and is normally blocked off by an end cap. The vacuum is more than sufficient to hold the caps on of course.

Small Vacuum system 003.jpgSmall Vacuum system 001.jpgSmall Vacuum system 002.jpg

As you can see space and particularly head room is limited. The skillion is only just above my head where the vacuum system resides.

As it happens this was very timely for me. The viewing window showed that there was some sawdust built up in the bottom container.

Small Vacuum system 006.jpg

But when I opened it up it was full and must have been so for a while as the dust was carrying through to the bag in the Vacuum itself.

Small Vacuum system 008.jpg

As you can see, the cone was chockers!

Here are some of the components disassembled:

Small Vacuum system 011.jpgSmall Vacuum system 010.jpgSmall Vacuum system 009.jpgSmall Vacuum system 013.jpgSmall Vacuum system 012.jpg

You cab see the lower galvanised garbage bin absolutely full and there is a better picture of the ducted vacuum cleaner. The plastic 20L drum has a fuel funnel fixed in place with some silastic. The drum is slightly tapered and the large funnel just pushed into place. Some of the tapered tube on the funnel is cut off. I think I should have cut all of it off on reflection.

Of course the vacuum exhaust exits outside the shed.

Small Vacuum system 016.jpg

I believe the principle of this system can be adapted to a full size DC. Cyclones are either expensive to buy or complicated to build and they add a restriction to air flows (thanks to BobL for all his input there). If a system such as I have described can capture 85-90% of dust compared to 90-95% with a cyclone, would that make it cost effective.

Build a box in the proportions of 1m square (that should probably be cubed) or bigger if space permits from scrap materials and give it a go.

Just one thought I have had is that the vacuum effect on a cube may pill in the sides so some reinforcing will be needed or a circular drum may be stronger. probably everything will be good until the container starts to fill or a blockage occurs. While air can flow in and out all is good.

Regards
Paul

Thanks again guys - those pics give the creative juices some ideas to mess with for a while bushmiller, mucho appreciated!

Yes Bob, 4 inch is too small - I realize that, - and will make something based on a minimum 6 inches - even if it kills me, I promise.

Cheers!.

I've been looking through Bill Bentz site over the last day or so (I'm still crook as a dog with the flu and laid up for over a week now) because I seem to remember that a lot of your concepts and questions raised in this thread were addressed by BP somewhere in his site.

Anyway I finally found the page concerned and it is the FAQ on this page: Bill's Cyclone & Dust Collection Research - Cyclone Building Instructions
Buried amongst all that is why almost all small cyclone designs and taking a standard cyclone design and just scaling it up and down won't work on standard DC motors and impellers.

BPs stuff can be very hard to read - a classic case of why stuff written for the Web should not be written in the same way as it is for paper - but it's basically all there.

It's interesting to note the following: BP says that if you use a DC with X HP motor and blower and you add a standard cyclone you need an ~1HP of additional power to recover the flow rate back to the original flow rate of a DC. This is actually a simplification for the masses since some smaller impellers already operating on their limits can never recover the pressure drop imposed by inefficient cyclone designs.

I'm thinking Bob - that by using a VFD on the standard 3 HP dusty, albeit with it's smaller 13 inch impeller... that we can gain say 20% extra flow rate by just spinning the impeller up to 60 htz rather than 50 Htz...

.20 x 3 hp = .6 or 2/3 of that extra one HP we need right there!

I have been speaking today with a major plastics roto moulder / injection molding co - with the view to using some of BP's figures - to come up with a cyclone & air ramp cylinder, based on 60 liter plastic drum dimensions* that clamps to a wheelie bin and takes a 6 inch duct from a 3HP dusty.

Add in the VFD and we won't get "the magic numbers" (4000 fps inside the 6 inch duct and 1000 cfm at the dust source) - but I will aim to get it as near as damn it to close as I can, given the limitations (3 HP & 13inch [330mm] impeller) & 6 inch PVC duct.

* The plastic 60 liter drums come standard @ ~ 398mm dia.... thus the cone length would need to be 1.64 x 398 = 652mm tall & the standard drum is 595 tall, so only a few mm short...

In essence 2 x 60 liter drums could make the cylinder with air ramp...(Lids already the right diameter for making the ramp), and cone... all that's needed is to clamp it to the top of a wheelie bin and add 6 inch duct from a 3 HP shop dusty & add a VFD to spin the little 13 inch impeller up to 60htz! for 3.6 HP.

This would be a no brainer for most Aussie workshops, sheds, garages etc.... admittedly it's not a PB 16 inch Clear View Max with 8 and 6 inch ducts & no change from $3 grand - but it might be a good stepping stone along the way - where the 6 inch ducting isn't wasted if someone upgrades to the CV & CVM further down the track.

Anyone wants to vent into their shop need only keep a clean needle felt bag on top of their dusty, or add a pleated cartridge filter... - otherwise vent the air outside, with the majority of the dust and chips in the wheelie bin thanks to the cyclone.

See what the plastics people say!

Maybe there's insufficient market?

Who knows?.

Marketing name? - When Full.... Wheelie Bin Laden!

So - the garbage guy pulls up and notices the wheelie bin isn't out the front on garbage day, ready for pickup...
Feeling somewhat benevolent he decides to knock on the door... and let the homeowner know so he doesn't have to go another full week with a full wheelie bin rather than just drive bye in the garbage truck & ignore the missing bin.
Homeowner answers the door to be greeted with a question from the garbo..

Q = "hey mate - wheres ya bin?"...
A = "AAhh, I bin everywhere mate - wheres yo bin?"
Q = " No, No, - wheres ya wheelie bin?"
A = "Well, I wheelie bin in jail, but don't tell the neighbors OK?"



Cheers