Ducting and Vent for external DC

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  • poolhound
    Veteran Member
    • Mar 2006
    • 3195
    • Phoenix, AZ
    • BT3100

    Ducting and Vent for external DC

    I am just at the point of moving my DC into position outside. I realized yesterday that the available room for the filter bag to inflate was much less than I had anticipated so I am guessing the top 10-15% will be scrunched up below the roof. Not sure if this will impede airflow and DC performance but it just accelerates the decision to vent directly outside.

    I am fitting the super dust deputy on the front end so the majority of chips and dust will be caught in that stage. From others who have the same setup (50-760 + SDD) they all say the fines that end up in the collection bag is a really small amount so I am hoping for similar results. I fully understand the make up air issue and that is not a concern and there is no gas heater in the shop.

    My questions relate to the ducting and vent. On the inside I am using 4" PVC so how big do I need to go on the external duct work and vent so as to not hamper the airflow. I was thinking 6" should be adequate. For the vent is there any difference venting on the side or through the roof . As I just finished adding the shingles I would rather not cut a hole without a good reason. You can see the setup in the pic below. two of the open panels will have doors and the middle one will be a fixed panel so could have the vent there.

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    Jon

    Phoenix AZ - It's a dry heat
    ________________________________

    We all make mistakes and I should know I've made enough of them
    techzibits.com
  • jussi
    Veteran Member
    • Jan 2007
    • 2162

    #2
    No answer to your question but am looking forward to following your progress. I'm installing a cyclone outside my shop. At about 9ft high I'm going to have to cut a chunk out of the overhang and reframe it.
    I reject your reality and substitute my own.

    Comment

    • Stytooner
      Roll Tide RIP Lee
      • Dec 2002
      • 4301
      • Robertsdale, AL, USA.
      • BT3100

      #3
      MY Home brew DC has been sitting in a similar situation for at least 13 years. No issues. Mine is covered a bit more, but still open to air. I do exhaust to outside and use a 6" steel pipe. You can elbow it down to exhaust into a water bucket to help catch the fines. Mine is not loud, but has a deep throated roar. Something to consider if neighbors are near.
      Lee

      Comment

      • poolhound
        Veteran Member
        • Mar 2006
        • 3195
        • Phoenix, AZ
        • BT3100

        #4
        Originally posted by jussi
        No answer to your question but am looking forward to following your progress. I'm installing a cyclone outside my shop. At about 9ft high I'm going to have to cut a chunk out of the overhang and reframe it.
        I saw that big yellow beast you got in that amazing deal from earlier in the year. With the shop you have built its going to need a lot of suck :-)
        Jon

        Phoenix AZ - It's a dry heat
        ________________________________

        We all make mistakes and I should know I've made enough of them
        techzibits.com

        Comment

        • poolhound
          Veteran Member
          • Mar 2006
          • 3195
          • Phoenix, AZ
          • BT3100

          #5
          Originally posted by Stytooner
          MY Home brew DC has been sitting in a similar situation for at least 13 years. No issues. Mine is covered a bit more, but still open to air. I do exhaust to outside and use a 6" steel pipe. You can elbow it down to exhaust into a water bucket to help catch the fines. Mine is not loud, but has a deep throated roar. Something to consider if neighbors are near.
          Mine will be covered once the DC is installed but its easier doing the work before I put the walls and doors on. had not thought about a bucket of water, do you exhaust near floor level then? Not sure about that here as not sure I would want dogs drinking it...
          Jon

          Phoenix AZ - It's a dry heat
          ________________________________

          We all make mistakes and I should know I've made enough of them
          techzibits.com

          Comment

          • cork58
            Established Member
            • Jan 2006
            • 365
            • Wasilla, AK, USA.
            • BT3000

            #6
            As far as the height problem you could always go with a filter instead of the bag. I have concerns about the bag rubbing on the roof and wearing a hole in it. I can just only imagine the look on your face when you open the door and see the mess!! I gave mine enough room so that top and sides have about a foot of clearance.

            My vent was just leaving the area under the eve's open. Probably more than what was needed but I know it is enough.

            I just ran 4" hose from inside to outside and haven't had single problem. My 50-760 runs allot of different machines from a 40X28 shop. A couple of long runs but they only see 2 1/2" hose the last few feet and work really well.
            Cork,

            Dare to dream and dare to fail.

            Comment

            • Stytooner
              Roll Tide RIP Lee
              • Dec 2002
              • 4301
              • Robertsdale, AL, USA.
              • BT3100

              #7
              I don't use a filter at all. My barrel collects most of the dust. What is left is fines. It sinks in the bucket after a bit. We have cats. They do not drink it, however even when we put fresh water out for them, they will drink from a stagnated pool left from rain first. Do they know something I don't?
              Lee

              Comment

              • capncarl
                Veteran Member
                • Jan 2007
                • 3564
                • Leesburg Georgia USA
                • SawStop CTS

                #8
                Poolhound, why not cut off the required amount of your delta dust bag? If I remember right it is held in place with a expansion ring? You could sew a hem in the cut off to prevent it from fraying. With your sys the full bag size is not needed.
                Don't forget to say goodby to your air conditioned shop air when you turn it on!
                capncarl

                Comment

                • poolhound
                  Veteran Member
                  • Mar 2006
                  • 3195
                  • Phoenix, AZ
                  • BT3100

                  #9
                  Originally posted by Stytooner
                  I don't use a filter at all. My barrel collects most of the dust. What is left is fines. It sinks in the bucket after a bit. We have cats. They do not drink it, however even when we put fresh water out for them, they will drink from a stagnated pool left from rain first. Do they know something I don't?
                  Thats my plan also. I was going to vent about 6ft above the ground but think I can figure a way to get some water under it.
                  Jon

                  Phoenix AZ - It's a dry heat
                  ________________________________

                  We all make mistakes and I should know I've made enough of them
                  techzibits.com

                  Comment

                  • poolhound
                    Veteran Member
                    • Mar 2006
                    • 3195
                    • Phoenix, AZ
                    • BT3100

                    #10
                    Originally posted by capncarl
                    Poolhound, why not cut off the required amount of your delta dust bag? If I remember right it is held in place with a expansion ring? You could sew a hem in the cut off to prevent it from fraying. With your sys the full bag size is not needed.
                    Don't forget to say goodby to your air conditioned shop air when you turn it on!
                    capncarl
                    Not sure I want to cut the dust bag in case I want to sell as a whole unit in the future for a nice cyclone upgrade. I am hoping the AC suck wont be too bad after all the wood whisper is also here in AZ and he said he didnt have an issue. we will see...
                    Jon

                    Phoenix AZ - It's a dry heat
                    ________________________________

                    We all make mistakes and I should know I've made enough of them
                    techzibits.com

                    Comment

                    • capncarl
                      Veteran Member
                      • Jan 2007
                      • 3564
                      • Leesburg Georgia USA
                      • SawStop CTS

                      #11
                      No more than you would cut off it probably would never be noticed. I've got my delta dust bag left over from the cartridge filter replacement in my way if you want it. The thought just struck me, why not turn up a 3 large "cuff" on the filter bag like we use to wear on
                      blue jeans and pop the bag back in the collector?
                      capncarl

                      Comment

                      • poolhound
                        Veteran Member
                        • Mar 2006
                        • 3195
                        • Phoenix, AZ
                        • BT3100

                        #12
                        I actually got the DC all situated outside at the end of last summer but didn't quite get around to finishing off the outside. It had been protected by a tarp since then and LOML has been hinting very heavily over the last few months that she wanted it DONE! SO got some more siding and some scrap 2x4s and now its all enclosed with door access to empty the chips and dust. I still need to get the woodstore tarp walls cut to fit but this little project will be 98% done by the end of the coming weekend. I still do need to test how the system may perform if I remove the bag but that can wait for a while.

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                        Jon

                        Phoenix AZ - It's a dry heat
                        ________________________________

                        We all make mistakes and I should know I've made enough of them
                        techzibits.com

                        Comment

                        • Bill in Buena Park
                          Veteran Member
                          • Nov 2007
                          • 1865
                          • Buena Park, CA
                          • CM 21829

                          #13
                          Looks good Jon. One thing you might consider - instead of ditching the bag, replace your lower bag with another filter bag. This increases the airflow output, and the fines don't accumulate all that quickly in the lower bag. I did this to mine almost a year ago, and even with all the fines I capture from sanding on the lathe, there's only about two inches of dust in the bottom bag.
                          Bill in Buena Park

                          Comment

                          • poolhound
                            Veteran Member
                            • Mar 2006
                            • 3195
                            • Phoenix, AZ
                            • BT3100

                            #14
                            Originally posted by Bill in Buena Park
                            Looks good Jon. One thing you might consider - instead of ditching the bag, replace your lower bag with another filter bag. This increases the airflow output, and the fines don't accumulate all that quickly in the lower bag. I did this to mine almost a year ago, and even with all the fines I capture from sanding on the lathe, there's only about two inches of dust in the bottom bag.
                            Interesting thought. CapnCarl had said he has a spare bag so I will PM him and see if I can try that. Even from an academic perspective I have been meaning to setup a simple liquid manometer to measure the suck. I wanted to test with clean/dirty bag and without a bag and see what difference it makes. I also wondered whether size of the fine collection bag made any difference. I cant see why but who knows. If I can make it pretty small I could fit a larger compressor in the same space.
                            Jon

                            Phoenix AZ - It's a dry heat
                            ________________________________

                            We all make mistakes and I should know I've made enough of them
                            techzibits.com

                            Comment

                            • Bill in Buena Park
                              Veteran Member
                              • Nov 2007
                              • 1865
                              • Buena Park, CA
                              • CM 21829

                              #15
                              Originally posted by poolhound
                              ...I also wondered whether size of the fine collection bag made any difference...
                              If by "fine collection bag" you mean the original plastic type, there shouldn't be a penalty for reducing its size, since it doesn't allow air to exhaust through it. And your airflow may be best with all bags removed, but I didn't see if/where you are ducting to the outside, so wasn't sure if you'd abandoned that approach. Does that enclosure have any exhaust? If not, you might be creating back-pressure that could also diminish your airflow, and possibly trapping fines in suspension. I'm not an expert, but I don't think I'd be comfortable with the chance of trapping any fines in there with the electric motor.
                              Bill in Buena Park

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