"you don't want to buy a cyclone separator"

[Alan Schaffter]

I pretty much knew that, just didn't want to get into it. Personally, I am an advocate of no filter if at all possible.

[Chris Parks]

we flat-out don’t need an industrial solution for a hobby issue. Some of us choose to work wood and some choose to go the path of machine hot-rodding and collection -- spend your $$ accordingly. Bradley

So a 15" planer in a hobby workshop produces less (sub 3 micron) dust than the same planer in a professional workshop for the same number of passes through it?

I have found that this debate if it takes place in Australia against it taking place in the US concentrates on two different things. It seems that in the US all that anyone is interested in (as the primary concern) is picking up the big bits and never worrying about the sub micron dust which is the biggest concern. Here in Australia there has been some fairly detailed and dare I say a scientific approach that shows the what and how or at least opens up the myths etc surrounding DE for more discussion. This thread for instance has not once approached the fine dust issue and things like measuring with an anenometer are bad sources of data due to inherent shortcomings in the method giving skewed results. The cheapest method of picking up all the chips and curly bits is a shovel, why spend any more than that?

[Chris Parks]

I pretty much knew that, just didn't want to get into it. Personally, I am an advocate of no filter if at all possible.

We are fortunate with our climate and and I always advised my customers to not use filters which 99% do not need. It also makes the installation far less expensive.

[Joe A Faulkner]

One way to avoid the long runs (and thus the drop in CFM and SP) is to cluster tools around the DC. This particular configuration has always impressed me:
http://www.finewoodworking.com/works...-workshop.aspx

[Alan Schaffter]

You gotta be sure the filters are really effective and be really diligent about cleaning them.

[Michael W. Clark]

I pretty much knew that, just didn't want to get into it. Personally, I am an advocate of no filter if at all possible.

Ha! I knew you did Alan!

I don't like filters either, and prefer to leave them out regardless of system size. They can be a lot of maintenance, expensive, and take up quite a bit of room. However, sometimes they are the best solution in a given situation. There was a thread here a couple of weeks ago about a small operation in Vegas with about 8000 cfm of exhaust. If he has to condition this, it gets expensive and may make venting outside cost prohibitive. The best option may be small bagger units inside connected to work cells. If he does go outside, absolutely go high efficiency cyclone and eliminate the baghouse.

If the hobby system OEMs would supply a filter gauge and tell you where it should run, a lot of guesswork would go away.

I'm changing my cartridge filter on my home unit over to a bag. It's the same micron rating and inexpensive, even if I need a new one every year or so. I thought Jason made a good recommendation to the OP based on the description o f his situation.

[Bradley Potts]

Hey there Chris, #1 Unless I'm confused about another site, this thread did touch on particulate size a few times. Generally, it seems people readily accept that it's the small particulates that are a health concern, and this seems to point to most informed people pursuing a 1 micron level of filtration, however, 0.5 microns seems to be a recent option circulating about the wood blogosphere.

#2 It's not your 15" planer or 24" drum sander that is relevant here, it's the fact that our shops are smaller (short pipe runs) and we can only run 1 machine at a time that makes a king-sized difference between hobby and multi-station, mega-machine commercial shops.

[Bradley Potts]

Ha! I knew you did Alan!

I don't like filters either, and prefer to leave them out regardless of system size. They can be a lot of maintenance, expensive, and take up quite a bit of room.... .... The best option may be small bagger units inside connected to work cells.... ....I'm changing my cartridge filter on my home unit over to a bag. It's the same micron rating and inexpensive, even if I need a new one every year or so.

@Michael & @Alan, thanks for your input! Great sharing there! It's good to get straightened out and I appreciate it... time to "phone an engineer." Michael, the bit in your quote above sounds like what I'm proposing: for lack of a better expression, I'll call it "task" dust collection, with shaker bag filtration, scaled down to task-level performance. Right? From what Alan mentioned, it seems we want to stick to 4" inlets and ducting/piping.

In my previous posts, my main point is that the typical hobbyist shouldn't just swallow the hook on some wild, big DC solution, that there are real and unnecessary penalties for elaborate hardline systems and cartridge filters, and that those choices can exponentially expand the DC system cost beyond what a very simple yet functional system costs.

-- Bradley

[Michael W. Clark]

[QUOTE=Bradley Potts;2306512
In my previous posts, my main point is that the typical hobbyist shouldn't just swallow the hook on some wild, big DC solution, that there are real and unnecessary penalties for elaborate hardline systems and cartridge filters, and that those choices can exponentially expand the DC system cost beyond what a very simple yet functional system costs.

-- Bradley[/QUOTE]

Ducting can create a more elaborate system. However, its best to think in terms of flow and pressure, rather than HP and duct size. Flow is the flowrate of the air, often referred to as CFM for cubic feet per minute. The pressue is the static presssure (SP), this is the pressure that would try to collapse the duct and acts in all directions, US units are usually inches of water. The air is going to flow from high pressure to low pressure.

As Alan stated, you have to exhaust enough air from the tool to collect the dust. The flow and pressure required to do this is dependant on the tool and hood design. Closer capture hoods often require more SP, but lower CFM. Open hoods are the opposite. Once you get the dust in the hood, you have to convey it too the collector and clean the airstream. It takes SP to overcome duct losses, pre-separator losses, and filter losses (back pressure). The fan operates on a performance curve, the higher the losses (SP), the less CFM it will move.

Adding a pre-separator in front of a fan wil reduce the flow. How much? It depends on the fan, system, and separator.

However, here is the question to answer:

I'm making up numbers just to illustrate my point. Let's assume the single stage separator moves 1000 CFM with a clean filter and that the tool you are exhausting needs 800 CFM to collect the dust properly (or to your satisfaction). As the filter gets dirty, the flow drops and when it gets to around 700 CFM, you notice dusting at the tool and figure it is time to clean the filter. You clean it and the flow is now 950 CFM, next time you clean it, only 900 CFM and it was more frequent than the last interval.

You eventually get a new filter after the cleanings get less effective and install a preseparator to reduce the loading. The preseparator will reduce the flow because it has a pressure drop associated with it, but the flow is more constant over a longer period of time. It reduces filter cleanings and extends filter life.

The question is, with the addition of the separator, are you still able to provide enough flow to the hood to collect the dust? If so, you are golden, if not, dust will be emitted at the hood because it was not captured.

As far as duct size, depends on the flow you are pulling. If you want to maximize CFM, enlarge the duct. You can use about 50% more rigid duct length over flex duct because flex duct has more losses. If the flex duct is not perfectly straight, then you can use even more rigid duct and have the same duct losses.

My shop is small and cramped. I don't want to drag out the collector, so I have a small fixed duct system. I did it on the cheap when we first moved in with 4" S&D. My upgrade will be larger HVAC duct with tapered hoods for the tools and blast gates. Material cost will be about $250, so its similar to your additional collector, but all I have to do is hit the remote start and open the gate to use a tool.

[Bradley Potts]

Michael, thanks for the reply. What's "S&D?" Storm & Drain? Square & dampered? That's an impressively small cost for the upgrade; are yours pretty short runs? And what about make up air, I used to live very near your neck of the woods, and you gotta have AC in the summer and heat in the winter, right?

I'm going to end up with something like an 8'x20' shop, so I am very concerned about duct runs that interfere with storage, maneuvering space, and/or lighting. I just built out my roll-about 1000cfm setup, and I am not too happy about how noisy it is, and in fairness I must admit that my current solution is pretty large for a small shop space, and the 4" flex is a PIA to maneuver and hook up. So hopefully it's clear that I understand your situation with the limitations of a small shop and a small budget.

Without being argumentative here, I just get irked at how this dust collection business spirals so easily out of hand. For instance, it's clear that a single central collection system quickly hits a tipping point, at around 20' of pipe, that forces us to upgrade to a more powerful vac, which triggers bigger filters, larger ducts, a bigger cyclone, a bigger bin, more electrical capacity, more noise, and more makeup air -- ouch! From the architect's perspective, I don't want to spend more and have a noisier and more cramped shop as a result of the DC becoming Godzilla-sized. I sure hope moving the super-sucker around from tool to tool is not too tiresome, but it's going to have to do ... for now.

Take care, Bradley

[daniel lane]

Michael, thanks for the reply. What's "S&D?"

Sewer & Drain. It's basically non-pressure service (gravity service) pipe. Anything with "SCH 40" or "SCH 80" can handle pressurized service like supply, the S&D is for...disposal, I guess would be the word.

For dust collection, S&D is perfectly suitable and cheaper than pressure service PVC.



daniel

[Michael W. Clark]

Hi Bradley,
Daniel is right about the S&D. My price was just for the duct and fittings. You can add a little for some hose, clamps, and blastgates.

All my air is returned to the space through the DC filter. I'm in a small basement shop, about 12'x20'. Part of that is reduced due to a carve-out for the HVAC. The tablesaw, planer, jointer, mitersaw, shaper, and router (in the tablesaw wing) are all on one end near the DC. The other end is my bench, handtools, storage, etc. The drill press is also close to the table saw. So, yes, short duct runs.

I do DC system design and equipment for a living. I've thought about documenting my system changes, taking airflows before and after, etc., but I am not sure I want to mess with it in my free time. It could be a benefit to others and myself, but I don't get much shop time these days. I think I'll just hook it up and let it ride. I know it will move more CFM with a larger duct, but I don't want to drop out material in the duct either. I have a Jet DC-1100 and I would be willing to bet that it does not move 1100 CFM when connected to a system or a length of flex and a hood.

I would be curious to know if I can pull more CFM with an internal Thein baffle, bag filter, and larger duct (6" and 5") than I currently move with the 4" system and cartridge filter. May have to take a flow reading or two when I get ready.

Mike

[Brian W Smith]

"you don't want to buy a cyclone separator".........O.K.,roger that,I'll build it.....just sayin.We have a new(inhouse build) cyclone.It was custom fabricated from the ground up to not only serve it's primary mission.....but was built to fit in exactly the space we had to work with on a vert. panel saw.Pics,forthcoming.On a personal note,I got so bloomin pissed off on a certain aspect of the paint on this,It may not even get posted....but will try to get past it and shoot ya'll some pics.It was stupid cheap.We did all the sheet metal work,works like a champ.

[Michael W. Clark]

Without being argumentative here, I just get irked at how this dust collection business spirals so easily out of hand. For instance, it's clear that a single central collection system quickly hits a tipping point, at around 20' of pipe, that forces us to upgrade to a more powerful vac, which triggers bigger filters, larger ducts, a bigger cyclone, a bigger bin, more electrical capacity, more noise, and more makeup air -- ouch!

Thought about this a little,
You are correct because of what is available commercially. Technically, just because your duct run is longer, does not mean you need a bigger collector. It means you may need a different fan/motor to overcome the extra system losses. The cyclone and filters do not need to be any bigger because you do not need to increase the flow, only the SP capability to pull that volume through the system.

However, with pre-packaged commodity hobby systems, you do not have a choice to buy a larger fan/motor only. For example, I don't think you can buy a DC-1100 with a 1.5, 2, or 3HP motor. As you go up in motor size, you go to the larger system.

[Ryan Mooney]

I sure hope moving the super-sucker around from tool to tool is not too tiresome, but it's going to have to do ... for now.

My shop is a bit bigger than yours but still not huge and I started out with the theory that move around was more space efficient than ducting. Having live with it for ~3 years now I'm not as convinced. You have to have space to move it and it seems that that starts to add up to more space than it would take to just have it in place. In the end I ended up with a tool cluster and don't really move the DC much (unless I need to roll the BS to the front of the shop to do longer resawing in which case the DC follows). YMMV but walk though the workflow a few times and see how much space is saved or taken as the case may be.