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  1. #16
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    Re: Best Pricing locations for dust collection piping/hoses

    OK, here is the deal, for 2 hp or greater (if you want reasonable CFM):

    Run 6" duct- ALL THE WAY from the DC to each MACHINE, DO NOT STEP DOWN to 4".

    If using a cyclone have at least 30" of straight duct leading into it.

    Design your layout like a Christmas tree- 45 branches from a trunk. Avoid 90 bends (avoid running pipe around the perimeter of the shop.)

    Use 45 wyes NEVER a "T"

    If using metal, use true 45 wyes not low velocity wyes which have a big open space that causes turbulence and static pressure (reduces CFM).

    If using PCV, use ASTM 2729, also called thin-walled S&D, "solid perf," "gravity drain" and a few other names. You won't find it in Big Box Stores. Get it from plumbing (Ferguson) or irrigation suppliers.

    Do not use Sched 40 - way too expensive, especially fittings, and way too heavy

    Don't use SDR -35 (ASTM 3034) (also called sewer and drain) if you can avoid it. It often comes in blue/green at big box stores. Same O.D. as ASTM 2729 but thicker wall and heavier and costs more.

    Fittings- Use SDR 34/35, ASTM-3034, 3035, or 2729 fittings- 6" fittings (not pipe) are available at Lowes (and other sources) in the irrigation section not the plumbing section. Sched 40 fittings are the wrong size for ASTM 2729 (and SDR 35). Note: you might find some of these fittings in styrene plastic, not PVC- that's OK.

    Friction fit only, no glue/PVC adhesive needed- you'll reconfigure sooner or later. To help seal, after assembly apply a thin bead of silicone caulk (NOT latex nor latex blend caulk) to the outside of each joint. Use one small/short screw if you must. Silicone doesn't adhere to PVC very well so it is easy to remove- once set, you can peel it off or rub it off easily with a finger. Since joints are under suction, silicone stays in place and seals perfectly.

    Grounding is a waste of time and not necessary. PVC is a non-conductor so grounding will only remove the static charge at the exact spot of the wire, not from an inch away! Static can be a nuisance for sure, but in a home DC it is not a fire or explosion hazard. Google "Dr. Rod Cole, static shock" to read about it. If you want to ground something, ground the spiral wire in the really short length of 6" flex hose you should use to connect the duct to your machines. Static should decrease as the duct becomes seasoned.
    Last edited by Alan in Little Washington; 01-04-2019 at 01:45 AM.

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  3. #17
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    Re: Best Pricing locations for dust collection piping/hoses

    When I ran my ducts a few years ago I found I had more time than money. I was also a bit height challenged and didn't want to take up more room than necessary with the overhead ducting. My solution was to make the overhead ducting using melamine and tile board.

    Coming off the dust collector is standard 6" sewer pipe that I got from Fergusons. The pipe is not so expensive, but the fittings are. Going overhead I used an HVAC metal adapter to go from 6" round to 4"x12" rectangular. The overhead duct that forms the main trunk of the system is approximately 3.5" x 10" internally, which fits nicely into the 4"x12" rectangular fitting. The rectangular duct was made using melamine for the sides (cut in strips 3.5" wide) and then tile board for the top and bottom (cut in strips 11.5" wide). Where I needed to curve I made forms to glue up 1/4" HDF with the inside piece being tile board.

    It sounds more complicated in writing than it actually was to do once I got started. The cost per foot was a fraction of what I would have spent on other types of ducting.

    I built the whole system (including the cyclone, ducting and blast gates) following information found on Bill Pentz's web site (http://billpentz.com/woodworking/cyclone/). The system comes on automatically whenever I open one of the gates. It has a 5HP 240V motor that was recommended. I've used it for 10+ years and it works great. The only issue I've had to date was I had to replace the starting capacitor on the motor last year. Probably the best time/money I've spent on my shop was putting in a good dust collection system.

    Jim

    P.S. I agree with the previous reply that grounding is a waste of time unless you're in a high-dust environment (like a flour mill). I have never had any issues with static electricity and can touch the duct without any shock. That might not be the case if it were metal, though.
    "The society which scorns excellence in plumbing because plumbing is a humble activity, and tolerates shoddiness in philosophy because philosophy is an exalted activity, will have neither good plumbing nor good philosophy. Neither its pipes nor its theories will hold water." -- John W. Gardner

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  5. #18
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    Re: Best Pricing locations for dust collection piping/hoses

    Jim,

    We think alike. My first house (1968) had a basement with a 7' ceiling. The round duct work for the forced air heating system was too low. I replaced it all with home made rectangular duct. 3/4" pine and 1/8" masonites. It is still in use today.

  6. #19
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    Re: Best Pricing locations for dust collection piping/hoses

    Quote Originally Posted by creasman View Post
    Going overhead I used an HVAC metal adapter to go from 6" round to 4"x12" rectangular. . . . The rectangular duct was made using melamine for the sides (cut in strips 3.5" wide) and then tile board for the top and bottom (cut in strips 11.5" wide). Where I needed to curve I made forms to glue up 1/4" HDF with the inside piece being tile board.

    I built the whole system (including the cyclone, ducting and blast gates) following information found on Bill Pentz's web site (http://billpentz.com/woodworking/cyclone/).

    Jim
    As the saying goes, you get what you pay for!

    I know cost can be a big consideration to many, but if you had carefully read Bill Pentz, you would have known that running rectangular duct is just about the worst thing you could have possibly done for a dust collector (it is fine for low velocity HVAC)! The inside surface area of your rectangular duct is greater than the round duct it leads into so has much higher friction (inside perimeter of 6" round duct = 18.85 in. vs inside perimeter of 3.5" X 10" rectangular duct = 27" so your rectangular duct has almost 100 sq. in. more surface area for each foot of duct!!!! ). Also, flow is not uniform across a rectangular cross-section and the corners (all four of them) generate an unbelievable amount of turbulence. All of this really increases static pressure (SP) / destroys CFM. Dust and chips settling out of the air stream can also be a problem due to the impact of duct design on flow and velocity.

    You would have been better rolling thin melamine, high pressure laminate, or any thin, but rigid material, into a tube or using large cardboard carpet tubes. Compare cross-sectional areas: 6" round duct = 28.27 sq. in. vs 3.5" X 10" rectangular duct = 35 sq. in. or 4" X 12" rectangular duct = 48 sq. in. If you can find the static pressure per linear foot of rectangular duct for the size you are using (and DC velocities) and plot that on a fan curve- you will be shocked (horrified?) how much less CFM your setup generates than if you used round duct. Of course, if all you want to do is chip collection, that is fine.
    Last edited by Alan in Little Washington; 01-05-2019 at 12:50 PM.

  7. #20
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    Re: Best Pricing locations for dust collection piping/hoses

    I agree that round is better for the reasons you state but I did read Pentz's website from end to end -- several times. That was 10+ years ago and it may have changed, so I don't know what it says now. I did the calculations and came to the conclusion that for my application rectangular would be sufficient given the lengths of the runs and needed flow.

    As you state it's not as simple as comparing circular area to rectangular area. Shape matters. However, if your system has the pull and you go large enough it will work. I have the equivalent of a 6" run for the main trunks and drop down to a 4" round pipe for most of the tools. The table saw is the main exception, where I stay with a 6" all the way. The longest run ends at a turning lathe. I often run the system when I'm sanding a turning and it pulls out this fine dust without any problems.

    One problem I do find is that most tools are not well sealed. Even with a dust collector attached to the machine's port there are still many places for the chips and dust to escape. For example, my table saw is an older model without any sort of dust port. I had to build this into the base and found it helpful to also use insulating spray foam to seal around the table top and base. That made a big difference.

    Another component of dust collection in my shop is a homemade air filter. I have cabinets along one wall and rather than run these to the ceiling (where I'd have to use a ladder to reach the top shelf) I ran duct work in the soffit to filter the air. At the far end I mounted a fan I recycled from an HVAC unit to draw out the air and placed two 10"x20" filters in the soffit (one at the opposite end and one in the middle). If I'm using some hand tool that produces a lot of dust I'll run this fan. It does a quick job of cleaning out the air, same as one of the ceiling mount commercial units.

    As I've gotten on in wood working I've started to value hand tools and honing my skills with these. These don't make must dust, just shavings and some chips. I personally find my satisfaction goes up as well. Don't get me wrong, I'm not giving up my table saw, bandsaw, jointer, etc. But, I am using them less.
    "The society which scorns excellence in plumbing because plumbing is a humble activity, and tolerates shoddiness in philosophy because philosophy is an exalted activity, will have neither good plumbing nor good philosophy. Neither its pipes nor its theories will hold water." -- John W. Gardner

  8. #21
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    Re: Best Pricing locations for dust collection piping/hoses

    Quote Originally Posted by creasman View Post
    One problem I do find is that most tools are not well sealed. Even with a dust collector attached to the machine's port there are still many places for the chips and dust to escape. For example, my table saw is an older model without any sort of dust port. I had to build this into the base and found it helpful to also use insulating spray foam to seal around the table top and base. That made a big difference.
    .
    You might want to rethink that. You must leave sufficient opening(s) to allow for make-up air- No air in = no air or dust out!! It can be like a closed blast gate- no flow! A tablesaw of any type is problematic. No amount of suction on the cabinet will pull dust down through the blade insert or from the blade gullets, so much dust is thrown off the top of the blade (at the operator) at a speed faster than the velocity of DC air. A barrier + collection (over-blade pick-up) is necessary. As for dust that does get thrown from the blade into the cabinet, many people block all the little access holes between the cabinet and the cast iron top, slots around the elevation and tilt handles, etc.- not good!- air must be allowed to enter.

  9. #22
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    Re: Best Pricing locations for dust collection piping/hoses

    Alan,

    I agree with most of what you said but I disagree with your comments on dust collection at the table saw. The difference on airflow through the cabinet with a DC, regardless of the venting area, and without it will more than make up for some sealing of the openings. We also have to remember that a DC is a high volume, low pressure, air mover, however, so if you seal up the cabinet too well, the airflow will be greatly reduced but still more than what would occur just due to blade movement.

    I kind of agree that you can't get all the dust without overhead pickup but I tested the effect of different sized openings in the throat plate on my now "old" table saw, a Ryobi BT3100. I have an articulated cover on the back to block off that opening and magnets over the front openings to force as much air through the throat plate as possible. Dust collection if via a shop vac, a low volume higher pressure air mover. It never overheats. But I found that opening the back of the throat plate reduces the dust on the top significantly. On my new SawStop, I cut generous 1/4 wide openings in the Infinity throat plate inserts for the riving knife because of this effect. With the huge cabinet openings, my shop vac will not move enough air for this to make a lot of difference but when I hook up a DC, I think it will. Interestingly, even though the cabinet is quite open, the motor on my SawStop (1.75hp) has overheated once already. A DC should cure that too.

    I think larger throat plate openings are worthwhile and help with dust on top (edge cuts remain bad, however, for dust) and closing off the cabinet will not overheat the saw if you are using a DC. I intend to try the SawStop without sealing the openings, however, when I add a DC and see if the DC doesn't move enough air that I get reasonable suction at the throat plate. If I do, I will leave the cabinet openings as they are.

    Jim

  10. #23
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    Re: Best Pricing locations for dust collection piping/hoses

    Quote Originally Posted by JimD View Post
    Alan,

    I agree with most of what you said but I disagree with your comments on dust collection at the table saw. The difference on airflow through the cabinet with a DC, regardless of the venting area, and without it will more than make up for some sealing of the openings. We also have to remember that a DC is a high volume, low pressure, air mover, however, so if you seal up the cabinet too well, the airflow will be greatly reduced but still more than what would occur just due to blade movement.
    I'm not following. I think you misunderstood what I said which is, if you block off ALL the misc openings in the cabinet and rely just on the blade insert (standard, zero clearance, or even dado whose openings on either side of the blade are just a fraction of the sq area of a 6" or even 4" duct) as your only source of makeup air, you are significantly throttling the air flow and only getting a fraction of the CFM through the saw and into the duct. In fact, the flow may be so impacted, you might end up with dust and chips settling out of the air stream, marginal separation in the cyclone, etc. Depending on the configuration of the cabinet floor (flat, steeply sloped, funnel shaped, etc.) you may still remove a certain amount of dust. But do the math- just take a typical airspeed (you can use 2500 or 4000 fpm for this comparison) and the duct/port diam. at your saw to compute max possible CFM. Then do the same with the total area of open space around the blade (2 or 3 sq in.?)!! Again, my extreme comparison still applies- CFM through a machine + duct = flow vs CFM through a duct with blast gate closed = 0 flow.

    I kind of agree that you can't get all the dust without overhead pickup but I tested the effect of different sized openings in the throat plate on my now "old" table saw, a Ryobi BT3100. I have an articulated cover on the back to block off that opening and magnets over the front openings to force as much air through the throat plate as possible. Dust collection if via a shop vac, a low volume higher pressure air mover. It never overheats. But I found that opening the back of the throat plate reduces the dust on the top significantly. On my new SawStop, I cut generous 1/4 wide openings in the Infinity throat plate inserts for the riving knife because of this effect. With the huge cabinet openings, my shop vac will not move enough air for this to make a lot of difference but when I hook up a DC, I think it will. Interestingly, even though the cabinet is quite open, the motor on my SawStop (1.75hp) has overheated once already. A DC should cure that too.

    I think larger throat plate openings are worthwhile and help with dust on top (edge cuts remain bad, however, for dust) and closing off the cabinet will not overheat the saw if you are using a DC. I intend to try the SawStop without sealing the openings, however, when I add a DC and see if the DC doesn't move enough air that I get reasonable suction at the throat plate. If I do, I will leave the cabinet openings as they are.

    Jim
    You are correct, a shopvac is totally unsuited for a cabinet saw. Shopvac= 80 CFM mx vs DC = 350+ CFM (hopefully).

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  12. #24
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    Re: Best Pricing locations for dust collection piping/hoses

    I too was concerned with creating a situation that might collapse the piping, so I installed a 'vacuum relief valve' in my pipe. I came off the 4" horizontal run with a 4" tee turned upwards, then put a 180 degree bend into it so it wouldn't become clogged with chips & dust. Inside of a 4' x 3" reducer I taper fitted a piece of 1/2" thick UHMW I had so that it would seat into the fitting. After drilling a center hole in this, I installed some 3/8" threaded rod and added washers until the valve would 'pop up' whenever sufficient vacuum was achieved on the system. Once the problem is solved, the valve will re seat itself. I had a photo of it in my gallery, but......
    WHAT BOX?

  13. #25
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    Re: Best Pricing locations for dust collection piping/hoses

    It sounds like our views are more aligned than I thought. I agree that operating a DC without adequate airflow will cause issues. I remain doubtful that cooling of the table saw motor is one but I agree completely that sufficient flow is necessary in the DC's ducts to move the dust and chips. My experience trying to seal up my table saws is that I wasn't terribly successful - they still leaked significantly. But if I seal up the SawStop, I will probably use a cheap wind speed meter to check airflow.

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