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Thread: Dust collector question

  1. #1

    Dust collector question

    I have a powermatic 3hp 1900 collector.

    Not getting the performance I'd like on my table saw, just have 1 10' piece of flex hooked up to it.

    It has the 8" to triple 4" adapter on it. Would i get a noticeable gain by using a 4" y in the reverse orientation from normal and hooking up 2 hoses?

  2. #2
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    You're starving the system for air with 4" connections...max CFM through 4" duct/hose is about 400-450 CFM. That's all you can physically fit in that diameter at the given air velocity. The best way to help improve performance would be to upsize the port on a tool and use 5" or 6" connections. Worse case, use the larger duct/hose to the tool and only reduce right at the port...it's not nearly as good as upsizing the port, but there is a small benefit from "venturi effect", anecdotally speaking.

    Those multi-port adapters that often come on DCs are confusing and more marketing than practical, honestly.
    --

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

  3. #3
    Thanks for the reply. Long term larger pipe is the plan but not ready to make that investment because my tools and shop layout arent all set yet. So curious in the meantime if the 4" y with 2 hoses would make a big difference as its easy and cheap.

  4. #4
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    Try it , you've got nothing to lose .

  5. #5
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    It really depends on how easily air is able to get into your tablesaw. If you've closed all of the big openings in order to increase the suction at the throat plate like many people do then increasing the flow capacity of the duct won't make much difference, the limiting factor is available pressure.

    What aspect of the performance are you unhappy with? Too much sawdust piling up in the cabinet? Too much fine dust escaping into your shop air? Something else?

    Can you post some pics of your saw?
    Beranek's Law:

    It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion.
    L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.

  6. #6
    My saw has the internal tube up to below the blade and overhead collection with one of those cheesy intenal splitter fittings. The air off the blade seems to push dust away harder than the overhead or throat plate collection pulls it in.

    https://www.harveywoodworking.com/pr...inet-table-saw

  7. #7
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    David is right . If it is starved for air on the intake side , big problem .

  8. #8
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    Quote Originally Posted by Garrad Miller View Post
    My saw has the internal tube up to below the blade and overhead collection with one of those cheesy intenal splitter fittings. The air off the blade seems to push dust away harder than the overhead or throat plate collection pulls it in.

    https://www.harveywoodworking.com/pr...inet-table-saw
    If you have a duct running overhead, then put in a Y fitting & drop a flex to the blade guard. I have a 2.5" flex to my blade guard & it works well.

  9. #9
    You seem to be asking of two 4 inch flex hoses have less resistance than one 4 inch flex hose. The simple answer is yes. Straight pipe is something like 1/3 the resistance of flex pipe too. I have a much smaller DC that does OK on my SawStop with a 4 inch port but I did one thing different and SS seems to have done something different. I ran 5 inch rigid pipe to within about a foot of the saw and then necked down to 4 inch to connect to the saw. Running most of the way in the larger and rigid duct helps. The other thing I am not sure about but my SS has a chute around the blade that helps to direct dust to the port. I get a light dusting in the bottom of the cabinet but it doesn't fill up unless the flex hose connecting the blade shroud to the port disconnects. If you do not have a shroud around your blade you might think about rigging something up.

    I also wye off a 3 inch line from my 5 inch rigid duct for overhead collection. It doesn't seem to affect the collection from the saw base, presumably due to the restriction of the 5 to 4 inch reduction at the saw. You might be able to do this for your setup too - maybe even use a necked down separate 4 inch line for your overhead.

  10. #10
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    I think you get that one 4" hose collapsing to that DC is throttling your performance. I don't know that running two 4" hoses versus a single 6" is anything other than a band-aid. If you already have the wye and the 4" hose you could certainly give it a try BUT, you will need to increase the collection point at the saw. I would rather cut one 6" hole as a long term solution than an additional 4" hole to test the greater through put. Running the two hoses and then re-collapsing them to a single 4" (if that is what I am reading) will probably be disappointing.
    Take me to the hotel - Baggage gone, oh well . . .

  11. #11
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    Given the internal shroud in the saw that likely has a hose diameter at or less than 4", if you decide to do the dual hose idea, connect one to the saw base and one directly to the overhead collection. (requires closing off the internal branch of course)
    --

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

  12. #12
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    I would buy a length of 6" flex hose and use that to the base of the saw. On my saw I cut a 6.5" hole and shoved in a piece of 6" pvc right under the blade running front to rear. I cut a 2x16" slit in the top of the pipe and capped the end. I have to pull the pipe for the few times I need more then a few degrees of tilt.
    I would use a piece of your 4" hose to suck off the top of the blade as well. Probably have to throttle that down to preserve flow in the 6". No one ever suggests adding an airline to blow the chips off and away as is common on metal working saws. Or adding a rotary brush to a bandsaw..
    Bil lD
    Bil lD

  13. #13
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    Quote Originally Posted by Garrad Miller View Post
    My saw has the internal tube up to below the blade and overhead collection with one of those cheesy intenal splitter fittings. The air off the blade seems to push dust away harder than the overhead or throat plate collection pulls it in.

    https://www.harveywoodworking.com/pr...inet-table-saw
    Like some Sawstop models, the problem with the factory setup is the small duct and tee fitting for the top collection. You can get a good bit of improvement by adding the second 4" hose like you want but, like Jim Becker said, connect it directly to the blade guard. Bypass that small duct and find or fabricate an adapter to fit the hose to the port on the guard.

    As an alternative that will quite possibly work even better, just connect the small hose to a shop vac instead of the tee.

    In both cases you close off the tee fitting at the bottom port.
    Beranek's Law:

    It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion.
    L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.

  14. #14
    Thanks have some good ideas to work with.

  15. #15
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    On a larger system like yours I've read that you should leave a second blast gate open if you are only pulling from one 4" port, so that you don't starve the collector. I have a 4" line going above and another 4" line below my table saw and the above-the-table collection is excellent. Below the table is... probably OK? The cabinet of my PM66 is not setup for airflow, just to dump dust at the bottom. But I believe that I need two 4" ports open on my 6" trunk in order to help my 2HP system out.

    Based on my reading, you want 4" ports for every tool, minimum, and if you can go to 6" at table saws and planers, so much the better. Rockler sells 6" dust baffles that can be used to retrofit a saw cabinet.

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