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  • table saw over blade dust colletion

    I'm getting ready to order a shark guard for my unisaw. Trying to decide between the 4" port or the 2.5". My table saw is first in line from my DC. I find the 4" port collector on the cabinet is working well, lots of draw. I wanted to do something similar to the sawstop set up; a branch off the 4" line that splits to the 2.5" port. Thought I could modulate the flow with a blast gate. I get lots of flow from the 4" line. My main trunk is 8" with a 6" drop going to the table saw with a 4" y out to the table saw. The 4" portion is only around foot and a half in length. Those running the saw stop set up how do you find it? Or am I better off just to put a second 4" 'y' in further up the 6" line for 4" connection on the blade? Thoughts, advice and experience is welcome.
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  • #2

    Re: table saw over blade dust colletion

    I don't have a sawstop or a shark guard, but if you have a 6" drop to your saw, than I would go for a 4" port on the guard and a 4" or 5" connection at the bottom of the saw. The total area of the 6" drop is greater than the sum of two 4" connections so you should have plenty of CFM available.

    I'm just starting to set up my new DC and will be posting a build thread soon so this is a timely question.

    David
    Last edited by DGB_WAT; 01-22-2018, 03:51 PM. Reason: Fix typo
    Shawn_S likes this.

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    • #3

      Re: table saw over blade dust colletion

      Yes, go with the 4” or you won’t get enough airflow.
      Shawn_S likes this.
      Erik

      Canada's Island Paradise - Prince Edward Island

      Proud member of the Wadkin Blockhead Club

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      • #4

        Re: table saw over blade dust colletion

        As David said, use a 5" for the saw body and a 3" or 4" for the overhead collection.............Rod.
        Shawn_S likes this.
        Work is the curse of the riding class.

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        • #5

          Re: table saw over blade dust colletion

          I haven't hooked up my shark guard yet (both my DC and the saw are mobile and have to be put away when I'm done with them, so I haven't spent the time to figure out how to make it easy to hook up), but I was amazed at the dust that came shooting out of the top of the 2.5" port on mine when I was cutting without dust collection from the guard!

          John
          Shut up, wretched cricket of doom...

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          • #6

            Re: table saw over blade dust colletion

            Yup,you guys are confirming what I thought was the right thing to do. The way my 6" drop runs, I don't have to branch off the 4" feed to the saw, I can put in another 4" branch off the line further up the run, so it would be closest to the main trunk and the DC. Like it is a feed to a whole other tool. If I set it up like this, would it be worth changing my run to the saw base to a 5" section or even a 6"? If my 4" works well now, will the flow decrease with another 4" run open a few feet ahead of it in the line? Not sure I explained that the best, may need to add a picture tomorrow.

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            • #7

              Re: table saw over blade dust colletion

              If possible, I would change the connection to the base of the saw to use 5". Does the saw have a 5" port or will you have to enlarge the existing one? Theoretically, if your mainline is an 8" pipe, you may have enough CFMs to run a 6" to the base as well as a 4" to the top of the saw, but that would probably be overkill.

              David

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              • #8

                Re: table saw over blade dust colletion

                Originally posted by DGB_WAT
                If possible, I would change the connection to the base of the saw to use 5". Does the saw have a 5" port or will you have to enlarge the existing one? Theoretically, if your mainline is an 8" pipe, you may have enough CFMs to run a 6" to the base as well as a 4" to the top of the saw, but that would probably be overkill.

                David
                It's a mid 90's Uni. It has the rectangular slot for the dust to exit, long and narrow. So if I where to put a 5" I would just have to form a different cover/adapter from the rectangular opening to the 5".

                Sent from my Life One X2 using Tapatalk

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                • #9

                  Re: table saw over blade dust colletion

                  Shawn,

                  I'll address your above-blade collection question first:
                  Based on my simple calculations for areas of circles (https://www.google.com/search?q=calc...ient=firefox-b), your idea of branching off another 4" from the 6" line going to your saw should work out just fine for the above-blade pick-up. I have a much smaller 2 1/2" connection feeding my above-blade guard and although it's good enough to suck small cutoffs and the majority of the dust up and away, it's as good as I'd prefer for small dust particles, which are the real culprits to worry about!

                  Again, if you think you'd be happy with the less flexible 4" above-blade connection (as compared to a 3", for example), then I say go for it. I am assuming you will have some sort of flex hose adjoining the guard and the non-flexible ducting, which will generate some static pressure loss... but not enough to worry about as long as you keep the length of the flex hose as short as possible.

                  Okay, so to answer your cabinet base connection question as to whether to stay with your 4" or go larger, just remember that if both of your feeds come off the 6" line, you're dividing that area (28.25 sq in) up between them. So far you've got a 4" (12.57 sq in) cabinet base line and are talking about another 4" (12.57 sq in) above-blade line. That leaves you some residual excess, which is good to have, as there's some loss due to static pressure from the connecting flex hose. But, and here's the but, if go with anything larger than your existing 4" line running off the same 6" line that your soon-to-be added above-blade 4" line uses, you will likely see no change in performance from your existing 4" line. So... if you want to go that route you'll have to run a separate 6" (or 5") feed from your 8" main duct line to satisfy the larger cabinet base boot. Here's the simple math: your 8" main duct provides 50.27 sq in; a 6" cabinet base line has 28.25 sq in and a 4" above-blase line has 12.57. The math works out in your favour as those two separate lines coming off the 8" duct = 40.82 sq in, but you'll have to factor in the static pressure losses to get a better idea of the performance.

                  Originally posted by Shawn_S View Post
                  Yup,you guys are confirming what I thought was the right thing to do. The way my 6" drop runs, I don't have to branch off the 4" feed to the saw, I can put in another 4" branch off the line further up the run, so it would be closest to the main trunk and the DC. Like it is a feed to a whole other tool. If I set it up like this, would it be worth changing my run to the saw base to a 5" section or even a 6"? If my 4" works well now, will the flow decrease with another 4" run open a few feet ahead of it in the line? Not sure I explained that the best, may need to add a picture tomorrow.
                  All the best,

                  Marty

                  President of Kingston Wood Artisans https://kwoodartca.wordpress.com/

                  Proud member of the Wadkin Blockhead Club

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                  • #10

                    Re: table saw over blade dust colletion

                    There's some pretty sophisticated math going on there, but I'll just tell you what I did. I've got a 4" flex connected to the cabinet & I put in a takeoff from the overhead duct with a 2" flex that drops down to the SawStop overhead collector/guard. It gets virtually all the dust, except when just cutting less than the thickness of the blade off the edge of a board. I think that's more of a design flaw with the guard though.

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                    • #11

                      Re: table saw over blade dust colletion

                      Originally posted by MartyFromKingston View Post
                      Shawn,

                      I'll address your above-blade collection question first:
                      Based on my simple calculations for areas of circles (https://www.google.com/search?q=calc...ient=firefox-b), your idea of branching off another 4" from the 6" line going to your saw should work out just fine for the above-blade pick-up. I have a much smaller 2 1/2" connection feeding my above-blade guard and although it's good enough to suck small cutoffs and the majority of the dust up and away, it's as good as I'd prefer for small dust particles, which are the real culprits to worry about!

                      Again, if you think you'd be happy with the less flexible 4" above-blade connection (as compared to a 3", for example), then I say go for it. I am assuming you will have some sort of flex hose adjoining the guard and the non-flexible ducting, which will generate some static pressure loss... but not enough to worry about as long as you keep the length of the flex hose as short as possible.

                      Okay, so to answer your cabinet base connection question as to whether to stay with your 4" or go larger, just remember that if both of your feeds come off the 6" line, you're dividing that area (28.25 sq in) up between them. So far you've got a 4" (12.57 sq in) cabinet base line and are talking about another 4" (12.57 sq in) above-blade line. That leaves you some residual excess, which is good to have, as there's some loss due to static pressure from the connecting flex hose. But, and here's the but, if go with anything larger than your existing 4" line running off the same 6" line that your soon-to-be added above-blade 4" line uses, you will likely see no change in performance from your existing 4" line. So... if you want to go that route you'll have to run a separate 6" (or 5") feed from your 8" main duct line to satisfy the larger cabinet base boot. Here's the simple math: your 8" main duct provides 50.27 sq in; a 6" cabinet base line has 28.25 sq in and a 4" above-blase line has 12.57. The math works out in your favour as those two separate lines coming off the 8" duct = 40.82 sq in, but you'll have to factor in the static pressure losses to get a better idea of the performance.

                      Thanks Marty. What you say makes sense to me, thanks to my many hours over the years combing the internet for DC information. Just want to clarify one thing you said. You said you have a 2-1/2 for you above blade, what is that running from? What is your set up as it pertains to your table saw?

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                      • #12

                        Re: table saw over blade dust colletion

                        I have 5" pulling below through the cabinet and a 4" above that reduces to 1.5" or so right at the blade guard,that is a sawstop I adapted to my splitter. It works quite well In Click image for larger version  Name:	image.jpg Views:	1 Size:	22.0 KB ID:	1161529 most cases. I used the 4" expandable hose from lee valley on the above the table drop,as I move the saw around,and this hose with its semi ridged,expandable design is excellent in this application

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                        • #13

                          Re: table saw over blade dust colletion

                          You get very little suction through 2.5" port with a dust collector. I have a good size cyclone (CV) and have a 4" port to the blade. Enough air flow.
                          Remember, we are here to share, learn, and enjoy. Relax.

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                          • #14

                            Re: table saw over blade dust colletion

                            You don't mention what your DC is, but since it's an 8" main, I assume it's substantially powered. So if you have the CFM from your collector to support it, and don't mind the bulkier hose and guard, I'd get the 4".

                            I have a 7" main to a 5" for my saw base, and then a 3" off the main further along to the over-blade... it goes into a Felder blade guard which I think is about 2.5" or so and it works really well most of the time. If you can power bigger it will likely be better.

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                            • #15

                              Re: table saw over blade dust colletion

                              Here is a picture of my above the table collection,the semi rigid flex hose from leevalley really helps keep the hose out of the way no matter of how the saw or blade is positioned Click image for larger version

Name:	image.jpeg
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ID:	1161708

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