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Thread: Dust Collection - Outside Exhaust

  1. #16
    Quote Originally Posted by Allan Speers View Post
    [/B]
    I seriously question that last part, though I am so expert and you may be correct. The way I understand it, if the main pipe is sealed, then makiing t as wide-diameter as possible is ALWAYS better as this reduces pressure on your blower.
    Nope. The issue is that you need a certain airspeed through the pipe to keep the dust suspended, and the required speed goes up on vertical runs. So if you make the pipe too wide, the dust will literally fall to the bottom of the duct and build up, giving unpredictable performance.

    Now it's true that a 6" duct that narrows down to 4" for a short segment will be better than all 4", but only if the speed in the 6" duct is sufficient to keep the dust suspended. So your best bet is to modify tool hoods if necessary to get 6" ports on the tool. (Or multiple smaller ports, like two 4" ports or a 5" and a 3".) If you're stuck with a 4" port, you might want to open up another port near that tool to ensure there is enough airflow (in CFM) in the 6" duct to get the necessary airspeed (measured in feet/min).

    One last thing...it's not enough to just put a 6" port on the tool, you have to make sure that there is enough opening on the tool for intake air to supply the air that's being sucked out. For example, don't go sealing up the tablesaw cabinet tightly, you need a certain amount of gap space for that make-up air to flow in.

  2. #17
    "The issue is that you need a certain airspeed through the pipe to keep the dust suspended,"


    Ah, that makes sense. Thanks.

  3. #18
    John,

    As you will see there is so much information on Dust Collection. I've read the a ton of blogs on here and on other sites. It can be very confusing, or maybe its just really confusing for me. I had an older Grizzly 2hp single stage unit and added a cyclone separator and vented outside. I don't have any way of calculating the CFM's but I have about 8 foot of 6" line then it drops to a 5" trunk line then to 4" at all my machines. I can attest that it increased my suction greatly. With venting outside you won't have any filters clogging or filter restriction. I have roughly $ 350.00 in the cyclone separator and the wood framing. At some point I will increase my trunk like to 6" and increase the size of my tool ports to either 5" or 6". My main killer on the old system was the drum sander.

    Good luck with your quest.

    Bill
    Attached Images Attached Images

  4. #19
    "The issue is that you need a certain airspeed through the pipe to keep the dust suspended,"

    I'v been thinking about this problem a bit more. Time for some patented Speers "outside the box" thinking:


    OK, so if the diameter of the trunk line is too big for a given CFM, your dust will settle at the bottom of the line and mostly air & super-fine dust will get to the impeller. I get this, no argument.

    And yet, it's also true that no matter what motor & impeller you have, a larger trunk puts less strain on the system and will result in more CFM - It just won't be EFFECTIVE CFM. So maybe there's a solution: (maybe)


    Idea #1: Use an 8" trunkline, but have a number of smaller-diameter junctions, to temporarily create a higher velocity stream of air. - Maybe one every foot or so. The idea is that these narrow ports would create enough localized air speed and turbulance to keep the dust suspended.


    Idea #2: Maybe there's a way to mechanically "shake" the trunk line, thus keeping the dust from settling & allowing a slightly larger diameter. Perhaps this in conjunction with #1.


    Idea #3: Put lengthwise "ribs" inside the extra-wide trunkline, then have a small motor slowly turn it, like they cook hot dogs at 7-11. Whatever dust settles would continuously get pulled to the top and dumped back through the air steam.

    ----------------

    OK, I didn't say this would be easy.
    - but it might be better than my "turn your lunchbox planer upside-down and use it as a jointer" idea.
    Last edited by Allan Speers; 07-06-2015 at 11:18 PM.

  5. #20
    I bought a Oneida 2 1/2 HP Super Dust Gorilla. I used it with the pleated filter for a couple of years. Then I plumbed it outside. Couple of things happened. The sound level was greatly reduced. The suction was increased and constant now. And the big one, if you let the barrel get overfilled it doesn't stuff the filter which takes 3/4's of an hour to clean out properly.

    Disadvantages are it'll suck out the heat or cold when you use it.


  6. #21
    At the risk of hijacking the thread, I find your outside the box ideas interesting, Allan. The problem I see with all of them, though, is they all introduce turbulence into the system, and turbulence will absolutely kill effective air flow. That's why recommendations for DC layout design say to minimize anything which will produce turbulence, such as sharp pipe bends and abrupt transitions in pipe diameter or shape. If my mental picture of Idea #1 - looking like a hank of sausages linked together - is correct, my guess is that it would be more detrimental to air flow (cfm) than a straight, narrow, uniform diameter pipe.

    One alternative that has occurred to me is to use an extra large diameter horizontal trunk, which will nor seriously affect air flow. Air speed will suffer, so saw dust will probably settle along the bottom of the pipe, but so what? (Let the chips fall where they may, so to speak!). Dust sitting in the pipe isn't causing any harm, other than risking moral outrage of those woodworkers like having their shop being perfectly clean. The dust is trapped in the duct, and not getting into the ambient air.

    As dust accumulates in the pipe, the effective pipe diameter will narrow, and air speed will increase, until it reaches a point of dynamic equilibrium , where the airspeed is high enough to start pulling some of the settle dust into the air stream, and keep dust suspended.

    This assumes that the weight of the dust wouldn't cause any structural stress on the duct, and also assumes there is no safety hazard, such as igniting settled dust by a static electricity spark. Just my own thought experiment...

  7. #22
    Just want to point out that if you're venting outside, there is no need for cyclonic separation. The cyclone is useful if you have filters, as it get more of the dust separated out, reducing the amount that goes to the filters. But if you're venting outside, there is no concern about fine dust going out with the exhaust, so you really only need some crude chip separation. A separator is likely smaller, cheaper, and adds less resistance.

  8. #23
    To update, I live in Los Angeles, so heat/cold is not an issue. Also, I can crack my garage door to make sure the pressure remains constant. So far, the cheapest and best deal seams to be the Clear-Vue-Cyclone (Model 1800) with no filters. It is only about $1500 and includes a 5HP blower and 18" steel impeller. I plan on running 6" ducting along the garage rafters and then modify as many ports as I can so that I do not have to neck down (I believe the 5HP will move sufficient air to pull the dust up the 6" ducting). I may have to neck down to 4" for a few tools on the drop-downs when that cannot be avoided. I'll also have to build a hood for my new Nova DVR lathe (to at least catch the dust if not the large chips).

    My last remaining issue is the volume. I live in a residential neighborhood and have nice neighbors. Ideally, I would like to build a little cabinet for the system behind my garage and then run the inlet line through a hole in the wall of the back of my garage. I was planning on using 3/4 MDF (potentially two layers) and then just throwing a coat of marine varnish on the whole thing (it rains about twice a year here). I could make some sort of baffle to allow ventilation to ensure heat buildup isn't an issue. Alternatively, I could build a cabinet inside my shop. However, I don't have much room, and the floor slab is so uneven I can't wheel things around easily so all my tools are shimmed up to level and not easily adjusted.

    Another quick question, would this setup (assuming I use efficient joints in the ducting and a minimum of flex tubing) be sufficient to extract dust from a router table and miter saw? I have been reading a lot on these forums, and some people suggest that a shop vac (festool or fein) is needed for these small hose dust extraction scenarios.

  9. #24
    Join Date
    Nov 2012
    Location
    Orlando, FL
    Posts
    280
    John,

    The Clearvue will certainly provide excellent dust collection and will work on pretty much all the tools you have. IMHO It's probably the best choice out there right now for a cyclone. Places where smaller hoses are needed can still be used with a cyclone, but the airflow would be reduced by the smaller openings. I have a cyclone that I use on the larger tools, but for things like a ROS, pickup from a hand held router, etc, I use a shop vac in connection with an Oneida plastic dust deputy cyclone. The airflow characteristics of the shop vac and the small cyclone (dust deputy) match the use of the smaller hose better than the larger cyclone. For a router table and miter saw the cyclone will work fine. The airflow problem can be solved by using two (or more) hoses wyed together and connected to the main 6" trunk line to insure enough air flow and get all the places dust and chips are generated. Example would be near the router bit in the fence, and below the table drawing from an enclosure surrounding the router. It normally wouldn't be practical to use 6" hose on the router table fence, but a 2" or 3" hose would work wyed together with another 4"-6" hose from the router enclosure. The miter saw could use a smaller hose from the blade shroud wyed together with a 6" hose from a shop built hood behind the saw. Your Nova lathe could use a large hood to catch much of what it generates. With a Clearvue cyclone pulling through a 6" hose if the lathe hood is well designed, it should catch nearly all of what comes off the lathe.

    If you live in a residential neighborhood and you exhaust outdoors, you really want the cyclone to keep your shop from spewing chips out onto the lawns in the area. It will catch something like 98% of the chips and dust you generate. The rest is just very fine dust that will dissipate with the wind. Using an enclosure is wise as it will lower the noise level for everyone within earshot.

    When I upgraded my DC, I went to 6" pickup hose. I have a small garage shop and move a portable DC to the tool. http://www.sawmillcreek.org/showthre...able-SDD-build The amount of increase in suction going from 4" hose to 6" was an eye opener. You may need to modify some of your tools to use 6" pipe, but if you use the "standard 4" you will choke the airflow the Clearvue will provide. Here is a look at some of the modifications I did to my machines. http://www.sawmillcreek.org/showthre...se-6-quot-pipe
    Last edited by James Gunning; 07-08-2015 at 2:23 PM.

  10. #25
    If your in a residential neighborhood are you at all concerned about the additional noise? The noise on mine is much louder outside than when my unit was running through a filter inside.

    I assume this is common?

    Bill

  11. #26
    Quote Originally Posted by William A Johnston View Post
    If your in a residential neighborhood are you at all concerned about the additional noise? The noise on mine is much louder outside than when my unit was running through a filter inside.

    I assume this is common?

    Bill
    True, but it's pretty easy to build a muffler out of MDF, 4 lb/ ft mineral wool, and something to waterproof it. (2-part epoxy paint?)

    You just have to make sure the outlet isn't mechanically coupled to the wall. A small bit of rubber or foam does the trick nicely.

  12. #27
    I've decided to go with the 5hp cleavue in a waterproofed, muffled, mdf outside enclosure with 6" mains and drop downs. I can modify most of my tools to accept 6" ports or 2 wyed 4" ports. I'm sure I'll be able to cobble together some hoods. Thanks for all the input. Saved countless hours and dollars not having to reinvent the wheel.

    Now ive got to design and buy the damn ducting. Lots of design ideas, but not much supply for pipe. 6" pvc pipe is expensive! Especially the fittings! Does anyone know a cheap online source? I figure sewer and drain pipes are the cheapest, but my nearby big box stores don't carry 6"

    any and and all help, ideas, and suggestions are greatly appreciated.

    Thanks,
    john

  13. #28
    Join Date
    Feb 2012
    Location
    Haubstadt (Evansville), Indiana
    Posts
    1,294
    You need to check plumbing supply places for the sewer pipe. Not sure of your location, we have Furgersons in my area.
    When working I had more money than time. In retirement I have more time than money. Love the time, miss the money.

  14. #29
    Southern California, Los Angeles Area.

  15. #30
    John,
    The ductwork isn't all that bad once you find it. I hung all my ducting in one day using some 36 inch long zip ties and screw on bases that I made but they can be found online to fit that size zip tie..http://www.waytekwire.com/item/21243...ng-Base-White/. I used about 15 total and I screwed boards to wall to hold system up more permenantly. Also if you have enough ceiling height to allow a split on the wall instead of putting them all on the main trunk it will allow less turbulance as there is half as many drops on the main trunk. I have a clearvue installed behind the door and can post pictures if you are interested.

    This might be cheaper than where you are. McMasterCarr ASTM 2729 Fittings According to those prices i have close to 1200 in my ductwork for 10 machines and a couple extra drops available.
    15 Wyes @ 24.30 = 364.60
    14 - 45's @ 12.33 = 172.62
    3 - 90's @ 21.71 = 65.13
    100' 6 in.@ 32.05 = 320.05
    10 Gates @ 15.00 = 150.00
    25' 4 in Hose = 45.00
    10' 6 in Hose = 65.00

    Matt
    FullSizeRender.jpgFullSizeRender (1).jpgFullSizeRender (2).jpgFullSizeRender (1).jpgFullSizeRender (2).jpgFullSizeRender.jpg
    Last edited by Matt Morgano; 07-15-2015 at 10:32 AM. Reason: added pics and link to pipe fittings

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