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Thread: If I don’t have a filter, is there any reason to have a cyclone?

  1. #1
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    If I don’t have a filter, is there any reason to have a cyclone?

    I haven’t found a discussion of this particular dust collection question and would appreciate feedback.

    From what I understand, a cyclone separator’s primary function is to reduce the volume of material that ends up in your filter. So if I don’t have a filter, is there any reason to have a cyclone?

    Context:
    I’ve got an old 1.5 HP Delta 50-760 (with 4” S&D pipe) with contractor saw, benchtop planer, jointer, router table, miter saw. Far from an ideal set up but I’ve only spent limited time the workshop on a project-by-project basis (kitchen cabs, built-ins, some furniture, etc.). Now, though, I’m anticipating more time in the shop during semi-retirement and would like to improve my dust collection a bit, without spending a fortune.

    After reading DC threads here, I thought about:

    1. Adding a cyclone separator, probably a Super Dust Deputy
    2. Replacing the filter bag with a pleated filter, probably from Wynn.


    However, it occurred to me that my set-up would allow for venting small stuff out a window (no immediate neighbors, hidden from view, moderate weather, etc.) and therefore may not need a filter at all. So now I’m thinking about plugging the filter bag opening in my Delta with a plywood disc that has a coupling for a hose to go to a window vent (similar to a dryer vent). This led to my question: if I don’t have a filter, is there any advantage in having a cyclone?

    Related:
    • If I close off the filter opening, accessing my Delta's plastic bag system for chips would be difficult, so I'd probably need to replace with a “skirt” and can system.
    • If I don't spend all that money on a pleated filter and cyclone, I may spring to upgrade to some 5" metal duct; maybe better bang for my buck there.

  2. #2
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    Quote Originally Posted by David Croteau View Post
    However, it occurred to me that my set-up would allow for venting small stuff out a window (no immediate neighbors, hidden from view, moderate weather, etc.) and therefore may not need a filter at all. So now I’m thinking about plugging the filter bag opening in my Delta with a plywood disc that has a coupling for a hose to go to a window vent (similar to a dryer vent).
    This is valid based on your stated situation.

    Quote Originally Posted by David Croteau View Post
    ... if I don’t have a filter, is there any advantage in having a cyclone?
    A properly-sized/plumbed system with a cyclone is going to remove most dust, shavings, chips etc. In your situation I would keep the cyclone to dispose of the waste rather than pumping that stuff into the outside air.

    In a small shop with fixed ductwork, the minimum is kinda 2HP. If you are rolling the Delta / SDD around to one tool at a time, you should be fine with 1.5HP /4".

  3. #3
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    Advantage to a cyclone, even if venting air outside, is that the debis all ends up in a bin without passing through the impeller and in a very controlled fashion. That also means you can take advantage of things like floor sweeps for general cleanup without risking metal sparking on impeller blades. But you can certainly use a simple blower to move material outside to an open bin or even a pile if you choose. I personally would never go back from having a cyclone...something I adopted in 2000 and upgraded a few years later to a larger unit.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  4. #4
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    Quote Originally Posted by Jim Becker View Post
    Advantage to a cyclone, even if venting air outside, is that the debis all ends up in a bin without passing through the impeller and in a very controlled fashion.
    Completely forgot about this! When small (<1") cut-offs make it back to my metal cyclone they make quite a racket. Would not want that regularly going through the impeller.

  5. #5
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    Quote Originally Posted by Jim Becker View Post
    Advantage to a cyclone, even if venting air outside, is that the debis all ends up in a bin without passing through the impeller and in a very controlled fashion..
    Ah, that makes sense. I hadn't thought about that advantage. Thanks.

  6. #6
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    Quote Originally Posted by Jim Becker View Post
    Advantage to a cyclone, even if venting air outside, is that the debis all ends up in a bin without passing through the impeller and in a very controlled fashion.
    Quote Originally Posted by David Croteau View Post
    Ah, that makes sense. I hadn't thought about that advantage. Thanks.
    Ding, ding, ding. Flowing spoil can be quite abrasive. Just take a look inside one of your pipes; mine are scoured squeaky clean. Not a deal breaker. Single stage units push spoil through the impeller all the time so the choice is yours.

    If I could do without a cyclone, I would. A separator puts a tremendous hit on your air flow. If I could just let it fly, I would be sorely tempted ;-) My current plans are for a cyclone with the post separator airflow blowing outside. My neighbors aren't quite far enough away for me to pump gallons of spoil into the wild several times a week . . . I'd scare the livestock.
    Last edited by glenn bradley; 11-06-2020 at 11:27 AM.
    "A hen is only an egg's way of making another egg".


    – Samuel Butler

  7. #7
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    Quote Originally Posted by glenn bradley View Post
    A separator puts a tremendous hit on your air flow.
    Yeah, I saw numerous posts mentioning this and it had me concerned, especially with a little 1.5 HP collector. (It's one reason I'd been thinking of jumping up to 5" ducts.) I'm hoping maybe some of this loss can be offset by the easier air flow of a no-filter set-up and by tightening up my duct connections. I guess we'll see.

  8. #8
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    The venting a cyclone out a window seems to work reasonably, as only very fine dust remains.
    I don't think sending all debris out the window is viable if you are generating regular sawdust, planer shavings, etc.

    To save cost, You might be able to run a thien separator with a 3hp+ blower and get enough separation to vent outside the window.
    Or look for a used cyclone in your area.

    Matt
    Last edited by Matthew Hills; 11-06-2020 at 4:12 PM.

  9. #9
    Add a Thien baffle inide your current DC. Separation is greatly improved, without changing foot print

  10. #10
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    Don't know your level of knowledge of fluid mechanics and I know it's been decades since I did any design calculations so I'm not sure how well I can explain this but here goes. Don't just replace the outlet filter with a plywood disc with a 4" hole and flex hose to the outside. You will get much less pressure drop and thus more flow if you can fabricate a gradual transition like a cone from the 20" or so diameter of the filter down to the 4" or so diameter of the outlet hose or duct. The bigger your outlet duct and the more gradual the transition the less back pressure on your dust collector fan and the more flow you will get.

  11. #11
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    It kind of limits your shop time to only good weather. You can not heat or cool a shop with a dc discharging all the conditioned air at several hundered cubic feet per minute.
    Bill D

  12. #12
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    Quote Originally Posted by Bruce Wrenn View Post
    Add a Thien baffle inide your current DC. Separation is greatly improved, without changing foot print
    That's what I have. A small amount of sanding dust type fines do make it into the filter but no chips or anything large.

  13. #13
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    IMHO you don't have enough fan to utilize a cyclone, way too much air flow lost in a cyclone.
    Make a cone for the top with at least a 6", 8" would be better to exhaust out side
    this will allow the best probable airflow you can get now, later when you upsize to a 5hp or bigger blower then consider a cyclone.
    Good luck
    Ron

  14. #14
    I use a "2hp" HF motor and blower mounted to the wall of my little shop, in the corner, sitting on top of a Super Dust Deputy. There is a home made plywood dust box under the cyclone and the air goes outside. I have 5 inch snap lock metal piping. There has never been noticable dust on the bushes closest to the DC exhaust. I sometimes use a little space heater in the shop in the winter but in SC where I am, the main thing is cooling. So far that is just a fan. I might go to a window unit for the hottest days. If I need to, I will add a filter. I have not measured airborne dust with my setup but in terms of getting the big chips out of the table saw, bandsaw, router table, planer, jointer, or CMS it works well. Leaving the doors open is part of my dust "solution". I will probably have to do something different to be able to leave the shop closed up. Simplest would be to add a fine furnace filter to the box fan I already have.

  15. #15
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    I just saw this and don't know if it was mentioned, but a good long-cone cyclone like the ClearVue will remove almost everything from big chips down to extremely fine sawdust. I use a 5hp ClearVue. I have good filters and return the filtered air to the shop but the separator is so efficient almost nothing even makes it to the filters. If venting outside, there would be very little sawdust in the exhaust stream.

    The short cone cyclones are not as efficient in the separation.

    JKJ

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