Phil Thein 60 , cyclone 0

[Alan in Little Washington]

Good to know, Thanks Alan.

How about a 1.5hp with one of those separators? If it's not gonna work well, collecting the fine dust as well as the chips, Then I have got a 55 gallon white/see through drum to get rid of.

Matthew

Here is the deal- a simple analogy- have a friend who is a smoker generate a small puff cloud of smoke, then ask him to suck it up with a straw- hard to do isn't it? That is what is essentially happening around your tools unless you keep that puff of smoke (dust) from leaving the machine. That is why I say the important part of dust control happens at the machine, not at the separators or filters and why you need max CFM at the machine. You need an adequately sized blower and ducting. Also, every single piece of equipment- pipe, fittings, flex, separators, filters, etc. between the machine and discharge (both sides of the DC) generates static pressure (resistance) and reduces CFM at the source. So the ideal is to eliminate as much of it as possible.

The ideal system (most efficient at collecting the maximum amount of fine dust), if you live in the woods, is one which dumps everything outside with no separators, filters, etc. Since few of us live in such an environment we must make compromises. But there is no getting around Mr. Bernouli- you gotta have suction first then minimal resistance to effectively collect and control the dust.

To answer your question, a 1.5 hp system depending on design- impeller size etc., etc. and how you use it, roll-a-round or fixed duct system, and a separator, will work (one tool at a time) to a reasonable degree, as long as you don't burden it with too much or too small of hose/pipe and filters that clog- hence discharging the relatively chip-free (but likely fines laden) air outside. There is no "this works" and "this doesn't", it is all a matter of degree.

Just my 2 cents but I never intended for my dust collection set up to collect the fine dust that is generated, nor do I believe that it will collect the fine stuff. I use mine in conjunction with all the other equipment that is available, ie: dust masks, proper ventilation etc. I have just finished an air filtration system that should help with the fine particles so I believe that I am doing all that I can to reduce the amount of dust that I ingest.

That is a good approach. Just remember, the really fine stuff can stay airborne for 30 min.or longer and is easily disturbed and sent airborne again once it has settled on horizontal surfaces, clothing, etc. Unfortunately, depending on the filter stack, most filtration systems do not filter out the fine stuff, they just circulate it and keep it in suspension giving you more opportunity to breath it. You will find some sources that say a mediocre air cleaner is worse than none at all. A mask and good ventilation, however, are excellent strategies.

I'll finish with this comment then get off my high horse. Unlike previous generations, more hobby woodworkers than ever before:

• Own and more frequently use more high dust generating tools and machines- because they are more available to consumers than ever before, especially sanders (belt, drum, ROS, OSS, etc.), have more money to spend on "toys", and more free time to use the tools.
• Work in confined, sealed, and insulated shops vs garages where they too often try to recirculate the DC collected air rather than dump it outside (industry doesn't attempt to do that!).

This situation hasn't existed long enough to yield any good data on the impact to the health of hobby woodworkers,but I suspect when available, it may not be good.

You can't beat Mr. Bernouli, so listen to what he says and design your dust control system accordingly.

 

[Glennbear]

Here is the deal- a simple analogy- have a friend who is a smoker generate a small puff cloud of smoke, then ask him to suck it up with a straw- hard to do isn't it? That is what is essentially happening around your tools unless you keep that puff of smoke (dust) from leaving the machine. That is why I say the important part of dust control happens at the machine, not at the separators or filters and why you need max CFM at the machine. You need an adequately sized blower and ducting. Also, every single piece of equipment- pipe, fittings, flex, separators, filters, etc. between the machine and discharge (both sides of the DC) generates static pressure (resistance) and reduces CFM at the source. So the ideal is to eliminate as much of it as possible.

The ideal system (most efficient at collecting the maximum amount of fine dust), if you live in the woods, is one which dumps everything outside with no separators, filters, etc. Since few of us live in such an environment we must make compromises. But there is no getting around Mr. Bernouli- you gotta have suction first then minimal resistance to effectively collect and control the dust.

To answer your question, a 1.5 hp system depending on design- impeller size etc., etc. and how you use it, roll-a-round or fixed duct system, and a separator, will work (one tool at a time) to a reasonable degree, as long as you don't burden it with too much or too small of hose/pipe and filters that clog- hence discharging the relatively chip-free (but likely fines laden) air outside. There is no "this works" and "this doesn't", it is all a matter of degree.



That is a good approach. Just remember, the really fine stuff can stay airborne for 30 min.or longer and is easily disturbed and sent airborne again once it has settled on horizontal surfaces, clothing, etc. Unfortunately, depending on the filter stack, most filtration systems do not filter out the fine stuff, they just circulate it and keep it in suspension giving you more opportunity to breath it. You will find some sources that say a mediocre air cleaner is worse than none at all. A mask and good ventilation, however, are excellent strategies.

I'll finish with this comment then get off my high horse. Unlike previous generations, more hobby woodworkers than ever before:

• Own and more frequently use more high dust generating tools and machines- because they are more available to consumers than ever before, especially sanders (belt, drum, ROS, OSS, etc.), have more money to spend on "toys", and more free time to use the tools.
• Work in confined, sealed, and insulated shops vs garages where they too often try to recirculate the DC collected air rather than dump it outside (industry doesn't attempt to do that!).

This situation hasn't existed long enough to yield any good data on the impact to the health of hobby woodworkers,but I suspect when available, it may not be good.

You can't beat Mr. Bernouli, so listen to what he says and design your dust control system accordingly.

Nice post Alan however IMHO there is another solution which I used in my shop to cut down on recirculation of dust which escapes the DC:


Here is a link to the thread explaining the design of my solution to the recirculated dust problem: http://www.ncwoodworker.net/forums/f81/dust-collection-control-23818/

 

[Mt. Gomer]

That is a good approach. Just remember, the really fine stuff can stay airborne for 30 min.or longer and is easily disturbed and sent airborne again once it has settled on horizontal surfaces, clothing, etc. Unfortunately, depending on the filter stack, most filtration systems do not filter out the fine stuff, they just circulate it and keep it in suspension giving you more opportunity to breath it. You will find some sources that say a mediocre air cleaner is worse than none at all. A mask and good ventilation, however, are excellent strategies.

Alan - How do you judge/gauge "good" ventilation. In addition to the DC (it's a woodtek and claims 1 micron filtration at the bags) I have a small (270 CFM) ventilation fan in the corner of my shop that is opposite the back windows. If I'm making sawdust I open the far window (more if it's not freezing) and leave the fan running. It's not a terribly fast air turnover due to the size of the fan but at least dirty air is always going out and and fresh air is always coming in. My shop is about 600 sq/ft w/ almost 8 ft ceilings. With the fan running that's about a full refresh in a bit under 20 minutes (if I did my math right). Is that adequate when combined with the aformentioned DC?

 

[Alan in Little Washington]

Nice post Alan however IMHO there is another solution which I used in my shop to cut down on recirculation of dust which escapes the DC:


Here is a link to the thread explaining the design of my solution to the recirculated dust problem: http://www.ncwoodworker.net/forums/f81/dust-collection-control-23818/

But . . . . you are adding a closet, and more filters- more resistance to flow down stream, which unfortunately adds more resistance to collection and reduces CFM at the machine end of the system.

Think of dust collection as one continuous pipe that starts at the machine and ends where the air flow leaves the system. You may be filtering the air that escapes from the bags, but you are adding more resistance- it is no different than putting a filter bag inside another filter bag. You would have a much more efficient system if you just vented your closet outside or just put the DC outside. Of course, since it is an end-to-end system you need to provide your shop with a source of outside takeup air.

 

[Alan in Little Washington]

Alan - How do you judge/gauge "good" ventilation. In addition to the DC (it's a woodtek and claims 1 micron filtration at the bags) I have a small (270 CFM) ventilation fan in the corner of my shop that is opposite the back windows. If I'm making sawdust I open the far window (more if it's not freezing) and leave the fan running. It's not a terribly fast air turnover due to the size of the fan but at least dirty air is always going out and and fresh air is always coming in. My shop is about 600 sq/ft w/ almost 8 ft ceilings. With the fan running that's about a full refresh in a bit under 20 minutes (if I did my math right). Is that adequate when combined with the aformentioned DC?

Any amount of air passing over your work area will significantly reduce your exposure to machine generated dust. The same is true of air being drawn over your bag filter. Going back to my smoke analogy- blow a puff of smoke in front of a window fan- it is rapidly collected and forced to the other side. The reason big axial window fans and furnace blowers are not used for DC systems is that while they can move large amounts of air (CFM), they lack suction (static pressure) to pick up and transport dust particles and chips through ductwork. Ideally, you want a system that maximizes both at the same time.

DC systems essentially operate most effectively in the range between window fans/furnace blowers and central vacs- at the middle of a fan curve- where there is enough CFM and static pressure. But your system configuration affects this- too large of ductwork and you lose static pressure and velocity, while too small of ductwork and too much resistance reduces CFM.

 

[Glennbear]

But . . . . you are adding a closet, and more filters- more resistance to flow down stream, which unfortunately adds more resistance to collection and reduces CFM at the machine end of the system.

Think of dust collection as one continuous pipe that starts at the machine and ends where the air flow leaves the system. You may be filtering the air that escapes from the bags, but you are adding more resistance- it is no different than putting a filter bag inside another filter bag. You would have a much more efficient system if you just vented your closet outside or just put the DC outside. Of course, since it is an end-to-end system you need to provide your shop with a source of outside takeup air.

I respectfully disagree that my system significantly decreases DC efficiency. The "bag within a bag" analogy is not a valid one. The discharge through the DC bag is released into the closet space and in order to create sufficient back pressure to be a problem the entire air volume in the closet would have to become pressurized. Air escapes through the filter in the door long before backpressure can build to significant levels. I will grant you that outside discharge would be ideal but for various reasons I do not consider that a viable option not the least of which is increased HVAC costs. Doing all of our woodworking under a laminar flow air hood would be an ideal situation however totally impractical. We must balance the "ideal" against practical considerations and personal preferences. I feel strongly that I have reached a proper compromise for me between "using a leaf blower once a week" and working under the afore mentioned laminar flow air hood. :gar-La;

 

[Alan in Little Washington]

I respectfully disagree that my system significantly decreases DC efficiency. The "bag within a bag" analogy is not a valid one. The discharge through the DC bag is released into the closet space and in order to create sufficient back pressure to be a problem the entire air volume in the closet would have to become pressurized. Air escapes through the filter in the door long before backpressure can build to significant levels. I will grant you that outside discharge would be ideal but for various reasons I do not consider that a viable option not the least of which is increased HVAC costs. Doing all of our woodworking under a laminar flow air hood would be an ideal situation however totally impractical. We must balance the "ideal" against practical considerations and personal preferences. I feel strongly that I have reached a proper compromise for me between "using a leaf blower once a week" and working under the afore mentioned laminar flow air hood. :gar-La;

You are missing the point! It is not that air stops flowing, it is that it doesn't flow as freely. If the cabinet is totally airtight, and air only passes through the filter in the door with no reduction in flow, the filter is providing absolutely NO fine particle filtering. Filtering is not a mystery- in simple terms it is small holes stopping bigger particles from passing through- that's it, nothing more than that, no magic. Filters designed for DC's require a lot of surface area (a lot of tiny holes over a lot of area) to be effective without impacting CFM severely. If it does any filtering at all, your filter is way too small for even the smallest DC's. DC's typically require filter area in sq. ft. (NOT sq. inches!) and the generally accepted value is 1/10th the CFM- e.g. a 1000 CFM DC needs at least 100 sq. ft of filter material- you will find this figure on many sites and sources, like Oneida Air Systems, Wynn Environmental, etc., etc. So, my bag-within-a-bag analogy is valid but a bit incorrect- your cabinet door filter is MUCH WORSE than a bag within in a bag!!

Every single bit of additional wickets you add to the air path, ANYWHERE along the air path- beginning, middle, or end, reduces CFM throughput- meaning you are reducing the volume of air collected at your tool. It is physics, it is Mr. Bernouli, you can't avoid it. How much a particular filter or other widget affects throughput can't be determined unless you use an instrument like a Dwyer magnehelic manometer and pitot tube setup, but believe me, everything other than a straight pipe does, and the diameter and length of the pipe do also! You can't say back pressure is not a problem unless you measure it. And yes, if that filter is working, then the air in you closet IS being pressurized, if it is not, then air is escaping through holes, under the door, etc. AND not passing through the filter in the door or the filter has large particle holes! That filter, no matter what the specs, big holes or little holes, creates some amount of resistance-back pressure, that can be measured, and it may be "significant" whatever that means.

Believe me folks, I'm not making this stuff up!

Now as to heat loss. I have said before, unless you run your DC continuously from the moment you arrive until you turn out the lights, which I doubt based on all the threads about remote contol switches, you are not losing as much heat as you think. Air is a poor thermal mass while your shop floor, walls, ceiling, benches, machines, etc. are. What that means is you can remove the heated air mass many times over, and your shop will reheat the new air quite easily. Will you need to add heat, sure, but it is not as bad as you might think. Analogy time again- does the compressor in your refrigerator turn on every time you open the door and ALL the 40 deg. cold air tumbles out and is replaced with 70 deg. air? Nope! Why not? - the thermal mass of the cabinet and contents quickly cools the new air.

 

[Glennbear]

You are missing the point! It is not that air stops flowing, it is that it doesn't flow as freely. If the cabinet is totally airtight, and air only passes through the filter in the door with no reduction in flow, the filter is providing absolutely NO fine particle filtering. Filtering is not a mystery- in simple terms it is small holes stopping bigger particles from passing through- that's it, nothing more than that, no magic. Filters designed for DC's require a lot of surface area (a lot of tiny holes over a lot of area) to be effective without impacting CFM severely. If it does any filtering at all, your filter is way too small for even the smallest DC's. DC's typically require filter area in sq. ft. (NOT sq. inches!) and the generally accepted value is 1/10th the CFM- e.g. a 1000 CFM DC needs at least 100 sq. ft of filter material- you will find this figure on many sites and sources, like Oneida Air Systems, Wynn Environmental, etc., etc. So, my bag-within-a-bag analogy is valid but a bit incorrect- your cabinet door filter is MUCH WORSE than a bag within in a bag!!
I stand by my original post that my system works and your bag within a bag analogy is flawed. I guess the fines I see on the inside surface of my filter are an optical illusion. I am not surprised that Oneida, Wynn and others disseminate such data since it helps boost sales of their filter media.:wsmile:

Every single bit of additional wickets you add to the air path, ANYWHERE along the air path- beginning, middle, or end, reduces CFM throughput- meaning you are reducing the volume of air collected at your tool. It is physics, it is Mr. Bernouli, you can't avoid it. How much a particular filter or other widget affects throughput can't be determined unless you use an instrument like a Dwyer magnehelic manometer and pitot tube setup, but believe me, everything other than a straight pipe does, and the diameter and length of the pipe do also! You can't say back pressure is not a problem unless you measure it. And yes, if that filter is working, then the air in you closet IS being pressurized, if it is not, then air is escaping through holes, under the door, etc. AND not passing through the filter in the door or the filter has large particle holes! That filter, no matter what the specs, big holes or little holes, creates some amount of resistance-back pressure, that can be measured, and it may be "significant" whatever that means.
I presume this "Mr. Bernouli" you refer to is Daniel Bernoulli (1700-1782) who was the author of a principle which today bears his name. I have a manometer from my days of working on commercial kitchen exhaust systems but to attempt to measure back pressure caused by DC bag discharge is ludicrous since it is patently obvious that the ratio of closet air volume vs volume of bag discharge does not impact DC performance. If there was sufficient closet pressurization to impact DC operation the DC bag would not inflate properly. That is not the case.

Believe me folks, I'm not making this stuff up!

Now as to heat loss. I have said before, unless you run your DC continuously from the moment you arrive until you turn out the lights, which I doubt based on all the threads about remote contol switches, you are not losing as much heat as you think. Air is a poor thermal mass while your shop floor, walls, ceiling, benches, machines, etc. are. What that means is you can remove the heated air mass many times over, and your shop will reheat the new air quite easily. Will you need to add heat, sure, but it is not as bad as you might think. Analogy time again- does the compressor in your refrigerator turn on every time you open the door and ALL the 40 deg. cold air tumbles out and is replaced with 70 deg. air? Nope! Why not? - the thermal mass of the cabinet and contents quickly cools the new air.

I have seen your thoughts on this before and I still disagree. Although the shop mass does create a "flywheel effect" on air temps the laws of thermodynamics mandate that matter will either lose or gain energy within a given confined space (the shop) until thermal equilibrium is reached. The shop structure and contents will give up BTU's to reheat the air or will absorb BTU's to recool it but the bottom line is those BTU's have to be replaced in the shop to once again reach equilibrium. The quantity of energy required ? I have no idea but apparently you have a clairvoyant means to determine how much energy I "THINK" I am using. I do KNOW that by not exhausting tempered air to the outside I am not spending ANY energy dollars to retemper make up air coming in at outside air temperature. Since you are a big fan of analogies here is one : If I have a bucket of water (shop) and place a sponge (untempered air) in it the sponge will absorb x ounces of water (BTU's), I can do this a number of times but at some point I am going to have to replace the water with more (additional BTU's) if I want to maintain a workable water level in the bucket (comfortable working temperature). I know that by NOT exhausting my shop air I have $0 energy dollar expenditures to bring untempered make up air to proper temperature.

"There is a principle which is a bar against all information, which is proof against all arguments and which cannot fail to keep a man in everlasting ignorance-that principle is contempt prior to investigation."

-Herbert Spencer

 

[MarkE]

Mr. GlennBear:

:thumbs_up :icon_cheers

 

[NCTurner]

Look the reality to this "discussion" is we are all going to do what is comfortable to us, at a price$ that we are comfortable with. I know that smoking is bad for me yet I still smoke, I know that sawdust is bad for me but I still breathe it. Hey while we are on the subject did you know that the eggs you buy at the grocery store not only contain high levels of steroids, and antibiotics, but are also often more than a year old, and in a lot of cases frozen and thawed??

 

[MarkE]

Look the reality to this "discussion" is we are all going to do what is comfortable to us, at a price$ that we are comfortable with. I know that smoking is bad for me yet I still smoke, I know that sawdust is bad for me but I still breathe it. Hey while we are on the subject did you know that the eggs you buy at the grocery store not only contain high levels of steroids, and antibiotics, but are also often more than a year old, and in a lot of cases frozen and thawed??

You smoke????

 

[Gofor]

Bruce, Bas, and Tony: Thanks for the info and pics on the Thein baffle. I really need to make one. It sounds like it will decrease my Ridgid shop vac filter cleaning time.:icon_thum:icon_thum:icon_thum

Go

 

[MarkE]

You should check out Phil's forum. There is a post there from a guy that built a nice Thein baffle for 6" pipe. Really cool.

 

[Douglas Robinson]

This thread is being closed at the OP's request.

 

[Alan in Little Washington]

[/COLOR]

I stand by my original post that my system works and your bag within a bag analogy is flawed. I guess the fines I see on the inside surface of my filter are an optical illusion. I am not surprised that Oneida, Wynn and others disseminate such data since it helps boost sales of their filter media.:wsmile:

I hate to go back and forth on this, but you are wrong again! You are telling me that the filter in the door provides absolutely no resistance to flow- impossible, can't happen. Every single filter made by man provides resistance to flow. That resistance varies by the design, volume and velocity of air attempting to pass through it, and the amount of time it has been in use (why we must change or clean filters). My "bag within a bag" analogy is valid- the inside bag is your DC bag while the outer bag is the small rectangular filter. (note: "bag" means "bag filter" not, a non-porous plastic bag)

No, no, no- you typically can't see fines until there is an extreme buildup. The human eye can't see dust smaller than 40 microns but woodworking creates dust from the sub-micron size (less than .5 microns) up to chip size. The dangerous stuff is .5 to 10 microns- it is invisible to the naked eye. You are saying the recommended 1:10, filter:CFM ratio is a marketing ploy! Wow! That leaves me speechless! (It is not! It is a computed value, base on resistance to flow and impact on CFM)!

I presume this "Mr. Bernouli" you refer to is Daniel Bernoulli (1700-1782) who was the author of a principle which today bears his name. I have a manometer from my days of working on commercial kitchen exhaust systems but to attempt to measure back pressure caused by DC bag discharge is ludicrous since it is patently obvious that the ratio of closet air volume vs volume of bag discharge does not impact DC performance. If there was sufficient closet pressurization to impact DC operation the DC bag would not inflate properly. That is not the case.

Yes, that Bernouli. And yes, a manometer with the proper scale will indeed easily measure the back pressure caused by the DC bag, and the filter in the door, too. How do you think they come up with the static pressure values for inches of pipe, number and type of fittings, cyclones and separators, AND filters?!?!? It is done all the time and not "ludicrous". "Ratio of closet air volume"??? What? The volume of air doesn't change. Whatever amount of air is picked up at the machine is also what must leave the bag AND the door filter. If you stop one you stop the other!!!!!! If you restrict flow through one you restrict flow through the others!!!! It is cumulative. And of course since your bag is inflated, there is resistance to flow- that is the case! A limp or inflated but not taught bag is providing less resistance than a taught one.

I have seen your thoughts on this before and I still disagree. Although the shop mass does create a "flywheel effect" on air temps the laws of thermodynamics mandate that matter will either lose or gain energy within a given confined space (the shop) until thermal equilibrium is reached. The shop structure and contents will give up BTU's to reheat the air or will absorb BTU's to recool it but the bottom line is those BTU's have to be replaced in the shop to once again reach equilibrium. The quantity of energy required ? I have no idea but apparently you have a clairvoyant means to determine how much energy I "THINK" I am using. I do KNOW that by not exhausting tempered air to the outside I am not spending ANY energy dollars to retemper make up air coming in at outside air temperature. Since you are a big fan of analogies here is one : If I have a bucket of water (shop) and place a sponge (untempered air) in it the sponge will absorb x ounces of water (BTU's), I can do this a number of times but at some point I am going to have to replace the water with more (additional BTU's) if I want to maintain a workable water level in the bucket (comfortable working temperature). I know that by NOT exhausting my shop air I have $0 energy dollar expenditures to bring untempered make up air to proper temperature.

You don't realize it but you almost agree with me here. I never said you would not need to add (or remove) BTUs. What I said was the thermal mass of your shop and contents is MUCH, MUCH, MUCH greater than the that of the air. For instance if you replace the air in a shop that is 70 deg. at equilibrium, with air that is 40 deg. the shop will attempt to reach equilibrium- the shop and equipment will give up BTUs to the air. But since the thermal mass of the shop is EXTREMELY large, MANY, MANY, MANY times that of the air mass, once at rest the the air will warm (and yes the walls, machines, etc. will cool) but the equilibrium temp will likely be close to 70 deg. at first and gradually decrease depending on how long you run your DC. As I said, eventually, if you continue to run your DC, you will need to add (or remove) BTU's to regain 70 deg. but it may take running the DC for an extended time before the at rest equilibrium temp is below 65 deg. Compare the numbers- the "volumetric heat capacity," the measure of the heat energy required to increase the temperature of an object by a certain temperature interval and another measure like thermal mass, of air at sea level is: 0.001297 (J/cm3K) while that of gypsum is 1.090 and wood 1.2 - 2.3 . The volumetric heat capacity of your shop and contents are about 1000 times that of air!! (You can read about it here)

No amount of truth or scientific evidence to the contrary will ever sway the determined skeptic. For those that believe no explanation is necessary. For those who do not, none will suffice. Investigation, education, and understanding are the keys to enlightenment.

 

[Canuck]

Thread closed as requested.