# Dust collection strategy



## lumberjoe (Mar 30, 2012)

Well, looks like I am a lifer in the woodworking world. The hobby has stuck and I am starting to transform my 2 car garage we don't park cars in from a storage shed/crap dump/work area to a real dedicated workshop. My next consideration is dust collection. Even though the place is kind of a mess now, I still break out the shop vac after every cutting operation. I haven't narrowed down the equipment I will be getting yet, however I need some tips as far as plumbing I want to run plumbing on the 3 walls without doors. My Table saw and band saw will be on one side of the shop, the drill press, band saw, jointer and router table on the other. I would also like a dust port drop off at all 3 of my work benches for when I do sanding/hand held routing. I want to run hard pipes along the wall with flexible hose to the tools. After my long explanation, here are my questions:

1 - most DC systems I have seen have one inlet. Is that the case?
2 - PVC or ABS?
3 - should I be worried about loss of suction if I have 6+ ports hooked up to dust collection at all times? 
4 - 2.5" hard pipe instead of 4" to the router table, band saw and work benches, or run 4" and reduce it at the tool? All of those things have 2.5" ports.

I picked up on a neat trick at my lumber mill. When they go between the jointer and planer, they insert a thin piece of sheet metal into a slot cut in the port that goes back to the DC on the machine not in use. Is that overkill or something I should consider?

Thanks for the tips in advance.

`


----------



## crank49 (Apr 7, 2010)

Most small systems will only function correctly with one port open at a time. In some cases, two ports work.

By small systems I mean 2HP collectors and yes they usually have one 5" inlet.

It would be best to use 5" duct, but that is not something easily found, and expensive if you do find it..

By two ports I mean a 4" and a 2 1/2" open at the same time. A setup used on router tables and table saws sometimes; 4" to the saw base and 2 1/2" to the table top blade guard for example.

I think what you refer to with the "sheet of metal in a slot in the port" is a homemade version of a blast gate.
Sheet of metal in a slot will have leakage that will rob the system of performance. Buy or make true blast gates for this function.


----------



## Charlie5791 (Feb 21, 2012)

That "thin piece of metal" is called a blast gate.  
Your suction goes down as you add length to the pipe. So the farther away you are from that DC, the less suction you'll have. Elbows also decrease suction equivalent to about 10 feet of pipe (each). I only have a couple machines I absolutely need on DC. My table saw and my planer. I want to put in some hard pipe so I can have other stuff on the DC, but it hasn't happened yet and it seems like I always have something else to do. Table saw and planer have quick connects and I have a 10ft flexible hose and I disconnect from table saw and connect to planer or the other way around depending on what I'm doing. Only takes a second. My shop is only like 1 and a half car garage size so I can roll my DC if I have to (for instance) position the planer closer to the door so I can pass long boards through it. (Stand outside to feed it into the planer….. we don't all have big shops … hehehhe)
And… I only run one piece of equipment at a time generally. I don't usually take a board, pass it through the planer, and then take it right to the table saw. Usually I'd pass everything through the planer and then I'm done with it. THEN go to table saw and do all THOSE cutting operations. For that reason alone, you might consider putting your DC on a cart or just get one that rolls. Take it where you use it.
You can get "Y" adapters so that's not a problem.
You can spend a lot of money on a DC capable of handling long pipe runs. Then you move a piece of equipment and you have to repipe to it. Think about it.

I will say that HAVING a dust collector is far better than NOT having a dust collector.


----------



## jmos (Nov 30, 2011)

Welcome to a confusing world; lots of info and ideas. If you want to read up I'd suggest Bill Pentz;s site. He has a lot of information there. http://billpentz.com/woodworking/cyclone/index.cfm

1 - Well, they kind of have to only have one inlet, right? Many, like my PM-1300 has an adapter installed taking the 6" to two 4", but can be removed. If you're running duct you should go with the one big inlet.

2 - PVC or metal is usually the question. Both can work fine. I suppose ABS can work too, but I think it would be pricey for an entire system. I'd make the call based on price and what's easily available to you. Pentz recommends PVC sewer and drain pipe, thin walled and cheaper than schedule 40 stuff. Also seems to think heavy (26 gauge) home center HVAC duct is OK, just avoid the thin 30 gauge stuff.

3 - As long as you have a way of shutting off the drops that are not in use, you won't have a problem (blast gates are the usual method.) You can NOT plan on leaving all the machines open to suction all the time and expect to get suction without a pro-shop size system.

4 - In general you want to run as large a pipe as you can for as long as possible, and keep the flex hose to a minimum. Both flex hose (rough interior) and small diameter pipe cause high pressure drop. As a general rule you're not going to get great suction from a DC through a 2.5" pipe, it's too small and the DC doesn't have suction that high. Might be better off with a decent shop vac for 2.5" ports. Better yet, try to increase port sizes to 4" (even converting 4" to 6" is good) which will allow the DC to move enough air to get good collection.

Lots of threads about this, do some searching on-site.


----------



## lumberjoe (Mar 30, 2012)

Thanks guys. I was looking somewhere in the area of a 3 hp DC system, like the G0562Z. I would only be using machine at a time, but I want to keep the clutter and trip hazards to a minimum. Thanks for the clarification on the blast gates. I assumed they would cause some loss of suction, but noting as dynastic as 6 open 4" ports. Would putting in something like a ball valve where the pipe goes from hard to flexible work better than a blast gate?

And john, thanks. I have been doing some searching but it just adds to my confusion. I'll check out that website you referenced, thanks! I asked about ABS because I have access to a lot of ABS for practically nothing.


----------



## MoPower (Feb 6, 2009)

Blast gates are the way to go. Ball valves are very expensive (try pricing a 4 or 6" ball valve, even a pvc 4" ball valve is over $40), an aluminum 6" blast gate is $12 and 4" is $8 on ebay, plastic blast gates are even cheaper.

I recommend a cyclone separator, a two stage system works fantastic.

I'll try to post some pics of my system later today.


----------



## crank49 (Apr 7, 2010)

With a 3HP machine you should be able to run 6" pipe.
I have a 2HP collector from HF and it does fine for one machine at a time.

Use no Tees, only Wyes for branches.
Two 45 degree elbows are better than one 90 degree elbow. Sweep ells are good.
Minimal use of flex duct is good.

It is not true that a 2 1/2" pipe won't work on a dust collector. Been working on mine for over a year.
BUT, you can't suck big chips, like from a jointer or planer through a 2 1/2" pipe. I use the 2 1/2" duct for sanding dust, and dust from my band saw, stuff like that, and it's fine.

Caution: Bill Pentz is not an engineer, but he has more than enough ego to be one. Some of his dribble is true, but take it for what it is. Ranting by someone with a giant sense of self worth. Buried in there is some pretty good information. I can interpret most of it because I am an engineer and worked with environmental systems for years, but I think some of his suggestions are way beyond what is reality.


----------



## lumberjoe (Mar 30, 2012)

I wish a cyclone separator was in the cards, but the 850 shipped for the griz is already pushing my upper limit. As it is I've spent over 3,500.00 on tools in the past 2 weeks, and I still am missing some key tools - like a planer, any kind of hand tool that is not a plastic handled embarrassment, and a drum sander since making cabinets is in my not so distant future. My total tool cap is about 10,000. That also has to include the 2,800 the electrician charged me to rewire the garage. 
That's not much to a lot of you and my wife and I do pretty well, but we also have 4 young kids - and I am not a professional so basically these are toys to me, so I do feel a tad guilty.

Michael, yes I will be using Wyes. Does it make sense to put a couple in-line on the longer runs and use them as clean outs (as long as they can be capped off)? I'm not sure how clogged up a 6" pipe can get. Also I see a lot of people use DC for floor sweepers as well. I have just started reading Bill's site and I am picking up on the self important vibe, but also see some things of value. I have a nice shop vac but I can't suck up big ribbons from my crappy hand planes. Is that a waste of time or worthwhile?


----------



## wapakfred (Jul 29, 2011)

You need to review the ducting cost for a good system, it will sometimes be as high as the DC itself. That said, most of that cost will be in the fittings and if you want to make things a lot harder you can fashion those yourself….it's a little easier with PVC, but metal can be worked as well. You could also build your own separator, the Thein model works well. As for floor sweeps, I had 2 in my last shop and never used them…didn't put them in the current shop and am now planning to add 2 (go figure), but I have a cyclone. With a single stage DC you might sweep nuts/bolts/something that's metal into the sweep and it might hit the fan and might spark and might cause a fire in your bags…probably more theoretical than real, but keep it in mind. I'm guessing your electrician put in a dedicated circuit for the DC? it'll draw some amps and always big running when the other big dogs are so it's best on it's own circuit. One other thing, in addition to the wyes, you might get some benefit by passing on the tight radius 90° elbows, instead use 2 - 45° ones with a short pieces of straight in between to soften the curve. Just some things to think about.


----------



## lumberjoe (Mar 30, 2012)

Thanks Fred. I am estimating my piping costs to exceed 1000.00 including fittings, which is why I would have a really hard time moving any further up the line than the Grizzly G0562Z. That is actually more than the DC itself, but I want to do this once, and do it right. I do have 4 dedicated circuits. two 110v and two 220v, along with a lot of other non-dedicated outlets. I am skilled at pulling cable, so I ran it all to code (or better) and had a licensed electrician terminate and inspect everything. I know DC will need to run along with other tools, as well as air filtration, dehumidifier, and heater in the winter, so at least I got that part planned correctly in advance. Good tip on the 45's and that is something I had considered. I think I am going to pass on the floor sweeps. I am a little sloppy and always drop screws and vacuum them up in piles of sawdust.


----------



## MrRon (Jul 9, 2009)

Probably the most overlooked part of a DC system is the blast gates. Like the rest of the DC system, all parts MUST be airtight. Home made blast gates are notorious for leaking and the slightest air leak will degrade any DC system by quite a bit. In use, only one blast gate should be open, allowing for the maximum air flow from that machine; BUT; make sure you always have one blast gate open or you can collapse the ductwork.


----------



## Vrtigo1 (Mar 18, 2010)

I used some of the plastic blast gates that came with my HF DC and I can tell you that they're junk. After a while they get sawdust built up in them so they don't close all the way, and even before that they leak. I just recently made a few homemade blast gates out of 1/2" plywood with a 1/4" plywood insert that opens or closes the gate. They work really well and they're dirt cheap.

Also, your comment about ducting on the three walls that don't have doors…in my garage I chose to go across the front of the garage (where the door is). I just went right over the top of the garage door with 4" PVC, no problems at all. Just wanted to throw that out there in case you were thinking the door would interfere somehow.


----------



## MoPower (Feb 6, 2009)

Just a few pics of how my DC system is shaping up.
I now have a 3 HP Grizzly DC , The 2 HP Harbor Freight worked fine in my old shop but with the longer ducting runs and the new Unisaw it just didn't have enough cfm.
The cyclone separator came from ebay ($199) I got it about 5 years ago and it works great.


----------



## AandCstyle (Mar 21, 2012)

Scot, that is one great looking shop!


----------



## kizerpea (Dec 2, 2011)

MY FRIEND U JUST BUSTED A CAN OF WORMS ON THIS TOPIC!! get ready for a over flow of info…


----------



## lumberjoe (Mar 30, 2012)

Scot, that's awesome. If I am not mistaken that is the DC I ordered. I also plan on getting the aluminum blast gates from Grizzly, unless someone confirms they don't work at all. They seem very reasonably priced. I am still finishing up a project that needs to get done for the boss (wife). After that the garage gets gutted and I start to lay out the pipe. I am going to try to use as little bends a possible when I lay it out. 
I am also running copper for compressed air with a few different take offs and putting in water separators. Is condensation a concern with DC plumbing? I have never heard about anyone making provisions for it.

Also one more thing that my father is insistent on that I have yet to see, but it makes sense on paper. He is a mechanical engineer and works in a large manufacturing facility. Vacuums create a lot of static, static can create sparks, sparks + fine dust = fuel-air bomb. He is insistent I run a bare copper wire through the system and earth ground it. That is going to add a considerable cost. Is this standard practice, or overkill?


----------



## wapakfred (Jul 29, 2011)

Don't waste your time grounding the system. The dust for an explosion would have to be so thick you couldn't breathe. The wire is nothing but a PITA when you make changes, and like you said extra cost. There is an article somewhere (can't find the link at the moment) that completely debunks the need to ground…if I can find it I'll post back and link it.


----------



## jmos (Nov 30, 2011)

Agree with Fred, grounding in theory is a problem, but for the size of a hobby DC system not an issue. Search LJ's, there's a link to a very detailed article about it showing it's not an issue, although I can't find it for you at the moment. It also addresses a number of methods to ground/dissipate charges that you can use if you like.

If you're really concerned use metal duct instead of PVC.


----------



## bytebullet (Feb 1, 2012)

This link came up in another LJ post a while back with reference to grounding.

http://home.comcast.net/~rodec/woodworking/articles/DC_myths.html


----------



## ducky911 (Oct 6, 2010)

I used sewer pipe in my shop. Sdr 35 is plenty strong and lighter than sch 40… I ran 6" to outside my shop and into a plastic shed with a griz 2 hp…i used 6×4 wyes and metal gates for each machine. You could hit sdr 35 with a sledge hammer and not dent it…you could even go with a thinner wall pipe but it was not as available where i live so i opted to go with th sdr 35. ...slip joint no gasket and no glue so i can change it around and i have. Joints slip together tight…no leak.


----------



## jmos (Nov 30, 2011)

Thanks Rod, that was the article I was thinking of!


----------



## lumberjoe (Mar 30, 2012)

That article helps and makes a lot of sense, thanks. I have an idea in my head now, I just need to sketch it up. I wrote some software to dynamically adjust VE tables (volumetric efficiency) on modified forced induction vehicles using speed density air metering, so I will adapt that a bit to get the best pipe sizing to maintain ~4000 FPM in the branches and ~3500 FPM in the main through some simulations, hoping the DC's advertised S.P rating of 16.1" is close to real world conditions.


----------



## teejk (Jan 19, 2011)

Scot

pretty shop you have there! (but why didn't you paint the osb hi-gloss white)?

it looks like your ran 9" oval for your "trunk" line (should be the same air flow as 6" round). I'll be talking to my HVAC guy about relative cost.

Joe

I have the "paralysis by analysis" thing going now…cyclones all seem to be priced the same at about $1,600 for a 3hp unit. OUCH! I'm only protecting 1,200 sq ft total but in reality my working area is less than half of that since other than the TS, the "nasty" dust producers (miter saw #1, #2 band saw #3 sanding table) are on wheels. I'm almost thinking that 2 decent mobile collectors would still cost a lot less than a cyclone and I could add a shared separator.


----------



## lumberjoe (Mar 30, 2012)

I'm pretty set on getting the ebay cyclone kits like pictured here
Unless someone talks me out of it. I've read a lot of people use these with a decent level of satisfaction


----------



## MoPower (Feb 6, 2009)

Joe, that is the same cyclone separator that I have. I have had it for about 5 years now and have had no problems with it.

teejk, my pipe size is 7" from the separator to the blower, and 6" throughout the shop. Eventually I will be mounting the blower directly on top of the separator, I will be making a filter box, adding two more filters and mounting them up high.


----------



## lumberjoe (Mar 30, 2012)

Nice! and since it looks like we have the same DC, it should work well. I'm going to order it in a few. As far as sizing, I think I am doing 8' from the DC to the 3rd branch, as the first 3 will all be 4" ports. The rest of the stuff all has 2.5" connections, so I will taper the main down to 6", run 4" hard drops, then taper down to the 2.5" to put the hose on. This is likely overkill but I have a feeling I will grow into it. I also decided I will put in a floor sweep.


----------



## MoPower (Feb 6, 2009)

The floor sweeps are nice, mine have only been installed for a few days and I'm already spoiled ! I plane to have at least 3 more.

I am running six pipe throughout and not reducing until I get to each piece of equipment. I don't really have one main trunk line except the first 4' at the separator inlet which is a series of 2 y's and one 90 splitting out to 3 different zones, two of which are now mostly complete. The table saw is a zone by itself with one tap that will have a vac hose attatched to it for clean up around the TS and possibly an over the table gaurd w/ dust collection attatchment later on.

The last section is really 3 sections, it will cover the end wall, back wall and a trunk running down the center with 2 drops from the overhead over each of 2 assembly tables. The latter being the next section to go in ( hopefully next week).


----------



## jmos (Nov 30, 2011)

Joe, I'm not sure I understand why you're tapering the run sizes? With only one tool running at a time, all you're doing by dropping size is adding pressure drop and thus reducing suction.

In a large system, with multiple tools running at one time, you increase duct size as you get closer to the DC, and more machines tie in, to keep the velocity as an optimal range which keeps the pressure drop from getting too high (per foot of duct).

I'd suggest you pick a duct size to get your target FPM and run that to as close to your tools as you can.

I'm sure everyone is aware, but I'll mention it just in case; if you duct size is too big the FPM will drop too low and the chips can drop out in the duct work


----------



## teejk (Jan 19, 2011)

ok jmos…dust collection seems to be the HOT topic in woodworking (and I'll confess that I smoke so health is secondary…primary is spending less time cleaning up the mess it makes).

are you saying to follow Bill 100%? I know he has spent a ton of time on the subject but for many of us he goes into too much science and detail (and I respect him highly for that). We recently built a house and a friend did the A/C system expaining static/CFM/placement of vents/returns etc. But as I read Bill, my head spins just about the same RPM.

so I'll ask a few questions to my HVAC guy on the topic (99% commercial work btw) and will post back.


----------



## lumberjoe (Mar 30, 2012)

That's how it worked out best on paper. I calculated the CFM I needed, then calculated S.P based on pipe diameter. I also plan on putting the blast gates at the wyes since the pipes will not be too high for me to reach. I may run 4 drops of the 8" pipe as I still need to get a planer. Running the whole main at 8# is not cost effective for me.


----------



## jmos (Nov 30, 2011)

teejk, some of the things Pentz talks about you do have to take on faith. Either his story rings true for you, or not. However, a good bit of what he says is simple fluid dynamics (I'm a Chemical Engineer.)

All I was pointing out is that if you run a main that is too big, even with good CFM (volume) the FPM (feet per minute, or air velocity) can drop to the point it will not keep the dust/chips moving well, and it can drop out and pile up in the duct work. If you go too small you have a lot of pressure drop. As most DC systems don't pull really hard, that can cause you to get poor suction. Earlier I pointed out that in some cases you may be better off with a shop vac, that does pull pretty hard, with a 2.5" hose, than a DC. Not saying it won't work, I do it myself (for my hand sanders and router table fence), but I'm usually not thrilled with the air it moves.

You can always do whatever you like; I'm very careful to suggest, I don't attempt to prescribe. I really dislike the folks that say they have all the answers and you have to do it the way they say or you're wrong. If you decide something, have at it. I would just hate to see someone, who is asking for input,to miss something because they we not aware of the issue.


----------



## teejk (Jan 19, 2011)

jmos

If my post sounded negative, then I wrote it wrong. Sorry! My facts are pretty simple… 30×40 finished work-shop space with the "normal" tools…I've abused it because I was finishing out our new house and didn't take the time to clean-up the shop regularly. Now with time on my hands, I think I have 2 weeks into capturing sawdust and I'm still not done.

That convinced me to embark on "collection at source"...reading here, it naturally linked me to Bill P's site. And then I started reading all the other posts about "cyclones" and "collectors" and "microns" etc. And then we get to "brands" (HF vs Grizz vs a host of others).

I consider myself to be of average intelligence but I gotta tell you…I have paralysis via analysis. And I don't think I'm alone. I hate the idea of buying a $500 tool only to know I won't be happy with it and end up selling it on Ebay for $150 (that $350 would buy a nice router and cutter set).


----------



## jmos (Nov 30, 2011)

teekj,

Sorry if I jumped, no offense intended or taken. I apologize.

I hear you, this is not an easy topic and unbiased data is hard to come by. I started woodworking about 2 years ago and bought a PM 1300. Over time I don't think it's cutting it; fine dust all over. I switched to a Wynn filter and trashcan separator and it's better, but my suction has taken a hit, so now I trap everything I suck up, but I don't suck it all up. Before I sucked everything up, but spat back all the fine dust into the air. I'm a bit miffed I spent the nut on the PM when it really doesn't do what it advertises (really filter out the dust to a 1 micron level at the CFM advertised). I'm skeptical many of the other systems can do what they say either.

My Wife is a Doc (chest specialist) and I'm asthmatic, so we're concerned. I'm planning on buying a cyclone this fall, so I've been researching. I find Bill's story compelling. He's offered his plan for free for anyone to build, see if you can get that from Oneida or PSI. He claims you need 5hp when the major vendors say you can do it with 2.5 to 3hp. Sounds too good to be true. I tend to believe him, although I can see why you might not. At this point I'm thinking I'll go ClearVue and 6" metal duct in my small (1200ft2) basement shop (I can't exhaust outdoors). Might be overkill, but I don't want to risk my lungs. I can not fault anyone for making a different call; I think just about anything is better than nothing.

Off to bed, so sorry if this doesn't make as much sense as I think it does.


----------



## MoPower (Feb 6, 2009)

I've read so many different article on dust collection that I was also suffering from paralysis through analysis. The difference is I've had the opportunity to experiment with various systems and setups over the last seven or eight years until I came up with a combination that seems to work rather well.

Although my goal was not so much to have a system in place for health reasons, it somewhat evolved into that for the health of the mini split heat pumps in my new shop (2 1-1/2 ton units with very small filters).

Although my system is not the cheapest, it is far and away cheaper than the factory built 3 HP 2 stage systems. Not counting ducting I have just over $800 in mine. Most of the ducting is surplus salvage given to me.

I hope to have it finished over the next couple of weeks ( darn job keeps holding me up), but so far it is working better than expected on the Table saw, jointer and planer.

I will continue to post progress reports and pics here and on the thread I started as it moves along.


----------



## MoPower (Feb 6, 2009)

jmos,

With your asthma I recommend a dust filtration unit, in the pics above you'll see where I installed one right above the table saw. It does a very good job of keeping the fine airborne dust under control and great for air circulation.


----------



## jmos (Nov 30, 2011)

Scot. Thank you and I agree. I bought one of those right off the bat too, PM1200. I also recently upgraded the filters in that to Wynn's. Seems to work better as well.

I've also got an order in for a Shark guard so I can collect at the top of the TS as well as the base. My Jet hybrid didn't come with a dust port in the guard.


----------



## teejk (Jan 19, 2011)

As I continue with my "analysis" that is causing my "paralysis"...

I continue to clean-up the shop floor (hard to do since every "sweep" seems to only put more dust in the air that will re-settle somewhere and then I have to wait).

But it made me wonder about something I've never seen mentioned. We live in a cold climate and I opted for radiant in-floor heating. My shop is enclosed with R19 on the walls and R50 in the ceiling.

I did a lot of work out there before we fired the in-floor and all the insulation was finished. I never saw that much airborne dust before.

John…that "fluid dynamics" stuff (sorry…I was finance!!!)...but building the house, I learned that unlike what most people think, hot air migrates to cold?

So if true, say the floor is 65F and heat with radiant tends to decrease with height (so perhaps it's 60F at the ceiling)...if all true, then that would explain why all of a sudden I seem to have dust everywhere.

John…as you said, there is no "authority" on the subject and now I think I have found another variable. I'll drop a note to a few of my experts and see what they say.


----------



## jmos (Nov 30, 2011)

I;m not sure about hot air migrating to cold; would need more clarification. It is true that warm air is less dense that cold air and rises. It is also true that if you have warm and cold air they will mix by diffusion causing the temperature to come to equilibrium.

Warm air rising is a good reason to put heat in the floor, as most systems do. The air rising off your warm floor could possibly be lofting some fine particles, but I'd be hard pressed to see it adding a considerable amount of dust into the air. That said, someone that actually has that system in their shop would obviously be a better person to talk to. Was the dust in the air something that started in the fall, but you didn't see last summer? If it is the heat it should be getting better now as it warms up and you're using your heat less.

From what you described, you're house sounds pretty tight. Was you last place more drafty? Maybe the new place is trapping more dust because it's tighter?


----------



## Gatorjim (May 12, 2012)

Wow my head hurts after reading all this. I just wish I could get a bigger shop vac. LOL


----------



## wapakfred (Jul 29, 2011)

Jmos, you're going to love the Shark guard. I went without overblade collection for quite a while before I made one…didn't like it, and bought a Shark. Some years later I snagged an used Excalibur Overarm, and now I'm thinking about switching back to the Shark…not only functioned better but is just easier to live with.


----------



## jmos (Nov 30, 2011)

Thanks Fred, that good to hear. I was looking at the Excalibur, PSI and other systems, but decided to go Shark. Glad to hear I made a good decision.

Lee was running about 9 week lead time; I should see mine early June. I'm really looking forward to being able to just remove the guard, leaving the splitter in place, when I use my crosscut sled. It is a real PITA to have to unbolt the stock splitter every time I need to crosscut something. I don't really mind for non-through cuts, don't do them nearly as often. And of course, dust collection over the blade will be great.


----------



## RobertsPlace (Aug 19, 2012)

Here is a section quoted from Bill Pentz's website relating the relationship between duct size and air speed and air volume. It can be found at the following website under letter d:

http://www.billpentz.com/woodworking/cyclone/DCBasics.cfm

"Almost all small shop vendors only offer 4" diameter ducting and tools with 4" diameter ports, yet most large stationary tools found in small woodworking shops need 6" diameter ducting for good fine dust collection. This is not rocket science. Airspeed and air volume are related by a simple formula FPM = CFM / Area where area is the ducting cross sectional area measured in square feet. Using a little algebra with our 4000 FPM and 800 CFM requirements and this formula shows we need almost exactly 6" ducting to move enough air at ample duct speed for good fine dust collection at most larger hobbyist tools. Anything smaller will not move the needed air unless we use a much larger than needed blower. Likewise, going much larger without getting a bigger blower will reduce the duct airspeed so much that we get dust piles and plugging in our ducting;"


----------



## kizerpea (Dec 2, 2011)

lumberjoe
i built my own set up to collect dust .it just takes a little time an some planing…in my projects.. works good to…


----------

