6 inch metal ducting from big box store versus the stuff advertised on Oneida-Air and Grizzly

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Forum topic by RonGoldberg posted 09-04-2013 03:19 AM 3037 views 1 time favorited 28 replies Add to Favorites Watch
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44 posts in 2356 days

09-04-2013 03:19 AM

Topic tags/keywords: question

Hey guys,
Here is the deal, I was a weekend hobbiest woodworker, but now my girls are in their teens and you guested it—they don’t want anything to do with me (I know it will pass, but hey, now I have ton’s of time to up my skills.
I want to get serious about dust collection. I work in the pharmacuetical industry and I am well aware of the dangers of wood dust inhaled over many years in the shop. So hear is the deal. I want a cyclone system with 6 inch trunk line with drops to the following machines: a) 2 HP Grizzly hybrid table saw b) Grizzly 6 inch jointer c) Dewalt 13 inch planner d) Grizzly 14 inch band saw and finally an incra router table. All the Grizzly tools have 4 inch dust ports, the Dewalt planer has a 2 1/2 dust port and the Incra Router table has a 2 inch dust port.

All the experts say, you want to use large ducting for the trunk line and try to maintain that circumference all the way down to dust port. Some when the duct drop from trunk, I will still use 6 inch duct dropping into a reducer (6 right to 4 inches) and then finally right into the dust port.

So hear is my question. Can I purchase all the ductwork at a Home Deport. For example a 6 inc steel duct that is 5 feet long is only $8 which is approximately 10 times less than the ones sold on the cyclone manufacturer’s websites. Even the Y-tube connector are about $6 versus about $50 on the cyclone manufacturer’s web site. Other than those cool blast gates that I can’t really find at home depot, it appears that I can save TONS of money by getting a Grizzly Cyclone and purchasing most of the ducting at a big box store, right? Or am I missing something here?

Lastly, I wanted a system that I can turn on and do woodworking rather than moving multiple shop vacs around to each tool. Since I only run 1 machine at a time and my shop is small (longest distance from cyclone to furthest tool is 11 feet of trunk line). All the other tools are within 6 or 7 feet from the Cyclone. That being said, Can I get away with one of the cyclones that are listed at 775 CFM. I know Bill Pence’s website recommends about 800, but he mentioned that he rounded up. The 775 should be enough for one tool as long as the ducting is 6 inches and I keep the blast gates closed for th other tools. Does this all sound correct. I showed my shop drawing to one of the other cyclone manufacturers and they had me ordering a 3 HP cyclone (my shop is only 10 feet by 17 feet = a mere 170 square feet). Comments and advice please. I would rather spend my money on good hardwood than excessive HP and systems that I don’t need. Thanks in advance for all your responses.
Ron G in McLean, VA

28 replies so far

View PaulLL's profile


160 posts in 1974 days

#1 posted 09-04-2013 03:33 AM

Im in the same boat, trying to get my dust collection set up properly in my garage, I’ve been moving my DC around to each machine and it’s getting old quick! I’m looking at adding the I Vac system to my garage as well.

View Grandpa's profile


3259 posts in 2673 days

#2 posted 09-04-2013 03:45 AM

I have collapsed the thinner duct pipes. Don’t want to do that. I used spiral wrap. It is $4 per ft. for 6 inch. Used the fittings from the heat and air section.

View dahenley's profile


136 posts in 2091 days

#3 posted 09-04-2013 03:53 AM

i cant comment on much… but i have been looking and wondering the same questions as you.

Bill talks about a lot of stuff and you need a min of 2-3 HP and X CFm….. but from my reading (on the forum) is that that CFM rating is for a conventional dust collector?

Cyclone collectors run less CFM then the bag/drum style because of design….

i know its not much help….. but maybe it will do something for someone.

Grandpa mentioned the spiral dust pipes. someone on here posted a link to somewhere that had it cheap….. (in respects to other types of pipe)
you might look into it.

-- David Henley

View copcarcollector's profile


256 posts in 2115 days

#4 posted 09-04-2013 05:03 AM

My ducting is 6 inch HVAC metal tubing from Home Depot. Your prices sound lower than what I paid, but that is what I used. Lots of aluminum tape, no screws at the joints. These go to 6-4 inch reducers , blast gate, then to 4 inch flex tube to each machine. Make sure to use Y connectors instead of T connectors to help the airflow. If you can, get a remote control on/off for your dust collector – makes life so much easier!

No problems with my system yet, sucks like a charm!

View copcarcollector's profile


256 posts in 2115 days

#5 posted 09-04-2013 05:22 AM

Luckily I am able to have the actual dust collector on the other side of the shop wall – so much quieter in the shop and saved floor space too! Here you can see the 7 inch pipe that comes of the DC, reduced to 6 inch and then on to the tools on the other side of the wall.

View RonGoldberg's profile


44 posts in 2356 days

#6 posted 09-04-2013 11:34 AM

Love that name! I have heard of the collapsed ducting problem. The cyclone I’m looking at is only 1.5 HP w 775 com. Do you think that would be problem w such a low power system.

All,you guys’ thanks for the comments. Send more pics

View Shawn Masterson's profile

Shawn Masterson

1325 posts in 1946 days

#7 posted 09-04-2013 11:44 AM

my 3hp unit crushed it like a beer can.

View Manitario's profile


2630 posts in 2880 days

#8 posted 09-04-2013 12:06 PM

the problem with the Grizzly DC you mention is that the 775 CFM is the airflow it produces with no ducting, ie. no restriction in the airflow. Add anything to it, even 6” duct and you add “static pressure” into the system which will reduce the airflow even more. I imagine that the real life airflow you’d get from it in your small shop would be closer to 300 CFM, especially with 4” ports on your machines. A small DC like the Grizzly can only do so much…there is a great static pressure calculator on Bill Pentz’s site (and you can find other calculators like it online); plug in the numbers from your proposed ducting and you’ll get an estimated static pressure (aka friction) that whatever DC you buy will have to overcome in order to supply even 700 CFM at any of your machines. For most small shops this means at least a 2-3HP DC.

-- Sometimes the creative process requires foul language. -- Charles Neil

View RonGoldberg's profile


44 posts in 2356 days

#9 posted 09-04-2013 12:47 PM

How about this configuration with 6 inch duct?
It can still run on 110V and If I am reading Bill site correctly (please correct me if not, seriously)—each machine that I have (and would be running solo) would only need 350-450 CFM. The one listed below is rated at 1025. My ducting requirement is main trunk line of only 11 feet (6”) with drops at 4 machines. If I connected each machine dust port (4”) to one of those 6” to 4” reducers with blast gate at each machine—would this be enough.
Let me know your thoughts. Much appreciated.

•Motor: TEFC Class “F”, 11/2 HP, 110V/220V, single-phase, prewired 110V, 18.8A/9.4A
•Cycle/RPM: 60 Hz/3450 RPM
•Switch: Remote controlled magnetic
•Intake hole size: 6”
•Bag material: Plastic
•Impeller: 121/2” steel radial fin
•Suction capacity: 1025 CFM @ 2.6” SP
•Max. static pressure (inches of water): 10.3”
•Filter: 99.9% efficiency captures 0.2–2 micron dust particles
•Filter surface area: 96 sq. ft.
•Collection drum: Steel, 35 gallons
•Overall dimensions: 55-1/2” wide x 87-1/2” high x 36-1/4” deep
•Body: 16-gauge steel
•Blower Housing: 11-gauge steel

View LakeLover's profile


283 posts in 1937 days

#10 posted 09-04-2013 12:48 PM

Last time at HD there was different thickness of ducting. Check the gauge, then compare.

View dhazelton's profile


2767 posts in 2294 days

#11 posted 09-04-2013 01:00 PM

Instead of HVAC pipe you could go to a place that sells furnaces and get the heavier wall 6 inch smoke pipe.

View Grandpa's profile


3259 posts in 2673 days

#12 posted 09-04-2013 02:32 PM
This is probably one of the most thoroughly posted installations I have seen. There is a safety valve here he has built that should help prevent duct collapse. I think every system should have one of these. There is a lot of reading on this link but take the time and read it. Make your decisions and then move forward.

View Fred Hargis's profile

Fred Hargis

4985 posts in 2491 days

#13 posted 09-04-2013 03:52 PM

If you’re going to choke the ducting down to 4”, that machine would be fine….the most you can move through a 4” duct is about 400 CFM (give/take) no matter what’s sucking on it. But gooing to 6” allows you to move much higher volumes (up to 1000 CFM), IF you have enough DC to move it. That would be one much larger than the 1.5HP you’re listing. BTW, that 1.5 HP has a 12 1/2” impeller, you usually see that size impeller on 2 HP motors. That could be a problem, so check the motor amperage once it’s hooked up. BTW, ignore most of the manufacturers CFM ratings, they are about as reliable as the 6.5 HP you shop vac has.

-- Our village hasn't lost it's idiot, he was elected to congress.

View Shawn Masterson's profile

Shawn Masterson

1325 posts in 1946 days

#14 posted 09-04-2013 03:57 PM

personally speaking. 4” pvc would probably be better for a DC of that size. If you run too large pipe size the airspeed will be slow and you run the risk of pile ups in the duct. imho I doubt that DC put out more than 700 cfm at the intake. Many companies are way over rating their figures, Mine is a 3HP with 14” impeller and the figures I sent to BP he came up with a realworld number of around 1000 Cfm and like 750 Cfm after the cyclone and pipe.

View wiswood2's profile


1138 posts in 3694 days

#15 posted 09-04-2013 04:07 PM

If you pvc make sure you put a ground wire in it and on the out side or you could have a big bang and a lot of fire.

-- Chuck, wiswood2

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