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Python chunk trap?

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  • #16

    Re: Python chunk trap?

    Originally posted by Rusty View Post
    If you can find a way to reduce airflow so as to drop a 2x4 and then have that same air magically speed up without a source of impetus, you will have created a new method of jet like propulsion. Good luck!

    Chances of picking up a 2x4 are slim in any case.Or at least should be.
    I think if you increase the diameter of the conduit and then decrease it this effect would be achieved. That said, you shouldn't be picking up big chunks of lumber in a dust collection system anyways.
    Egon likes this.

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    • #17

      Re: Python chunk trap?

      Originally posted by bender View Post

      I think if you increase the diameter of the conduit and then decrease it this effect would be achieved. That said, you shouldn't be picking up big chunks of lumber in a dust collection system anyways.
      Admittedly I'm probably not the person to ask or answer but it does seem to me if that were correct why is it that we are often told to use bigger pipe. How many times have we been told to increase pipe diameter from 4 to 5 or 5 to 6 inch to increase efficiency? Just thinking out loud.
      "Do it Right!"

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      • #18

        Re: Python chunk trap?

        Originally posted by bender View Post

        I think if you increase the diameter of the conduit and then decrease it this effect would be achieved. That said, you shouldn't be picking up big chunks of lumber in a dust collection system anyways.
        Yes. Air velocity will slow down in the larger area and again magically speed up when it gets to the reduced area discharge stream.
        Egon
        from
        The South Shore, Nova Scotia

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        • #19

          Re: Python chunk trap?

          Originally posted by Egon View Post

          Yes. Air velocity will slow down in the larger area and again magically speed up when it gets to the reduced area discharge stream.
          Egon I think that's true to the extent that if we reduce the air flow enough, with an air gun for example, the air comes out with more force but what happens down stream from the air gun? Isn't the air volume stagnated, [not moving enough,] to the point it won't carry anything?
          "Do it Right!"

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          • #20

            Re: Python chunk trap?

            On checking, you are right. Most fans are at the end of the system, or between the cyclone and the bag. So the cyclone itself is the chunk trap. I can see merit in a plastic cyclone just so that I don't get the pants scared off me when something goes CLANG!

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            • #21

              Re: Python chunk trap?

              Originally posted by Rusty View Post

              Egon I think that's true to the extent that if we reduce the air flow enough, with an air gun for example, the air comes out with more force but what happens down stream from the air gun? Isn't the air volume stagnated, [not moving enough,] to the point it won't carry anything?
              Closed system; what goes in comes out.

              In the smaller diameter pipe the air velocity is the same but in the large diameter area air velocity goes down. Pressure stay the same in all parts of the system.
              Last edited by Egon; 08-25-2019, 11:05 AM.
              Egon
              from
              The South Shore, Nova Scotia

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              • #22

                Re: Python chunk trap?

                Originally posted by Egon View Post

                Closed system; what goes in comes out.
                Actually, the air stream requires a minimum velocity to keep everything moving. If not, your ducting will start to fill. No different than the piles that build up in tablesaw cabinets.

                That is what this has been about: reinventing a trash can separator that introduces a zone of low flow, heavy particles fall out, clean air continues. This also comes at a price. The performance hit in SP losses are high.


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                • #23

                  Re: Python chunk trap?

                  Yes, in the enlarged space velocity declines, stuff drops out.
                  Egon
                  from
                  The South Shore, Nova Scotia

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                  • #24

                    Re: Python chunk trap?

                    And doesn’t come out.

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                    • #25

                      Re: Python chunk trap?

                      Not unless you have a trap door huh?
                      "Do it Right!"

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                      • #26

                        Re: Python chunk trap?

                        This might be what the OP is visualizing.

                        https://images.app.goo.gl/pQZrccvwqPFeHGhLA
                        https://images.app.goo.gl/doTHMfbw76fqmtpR8
                        Last edited by Egon; 08-26-2019, 07:30 AM.
                        Egon
                        from
                        The South Shore, Nova Scotia

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                        • #27

                          Re: Python chunk trap?

                          Second one was closer to what I had in mind, but with greater taper on the inlet and outlet lines, to reduce pressure loss. Ok. I'm reinventing the wheel.

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                          • #28

                            Re: Python chunk trap?

                            If you are concerned about sucking up big chunks how about a coarse easy to remove for cleaning, screen? When I sand small parts on my Ridgid oscillating sander I used to suck up small parts until I covered the end of my dust collector nozzle with a screen to avoid sucking the parts into the dust collector. Much less pressure drop and space required that either of the two devices illustrated. You could build a screen with a removable duct section upstream. If you suck up a 2x4, just shut down, pull out the removable section, remove the 2x4, replace the section and carry on.

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                            • #29

                              Re: Python chunk trap?

                              I'm not concerned with picking up large pieces of wood, but the shavings from a planer or jointer can block the entry to the dust collector. A cyclone is the easy solution. I have a Lee Valley cyclone lid on the shell from an old hot water tank - which works very well in separating out the bulk material.
                              Glenn

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