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

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5K views 28 replies 18 participants last post by  Finn 
#1 · (Edited by Moderator)
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
 
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#4 ·
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.
 
#5 · (Edited by Moderator)
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!

Building Gas Engineering Wood Machine


Wood Hardwood Flooring Engineering Machine
 

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#9 ·
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.
 
#10 ·
Manitario,
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
 
#14 ·
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.
 
#15 ·
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.
 
#17 · (Edited by Moderator)
i been using heat ducting in two shops for years
my present one is going to be moved to a larger shop
so doesn't have tape at any of the seams
i have a 6" 4hp sucker open to outside
(i live in the country)
so long as it sucks sawdust
there may be leaks in the line
so that may keep the tubes from collapsing
even when all the gates are closed

as long as the sawdust disappears
i don't worry about it
or try and 'improve' to some engineering 'perfect' specks

the airflow is reversed on the fittings however
so i make up a 'transition' starter to keep the seams right for it
i got a pair of crimpers for ducting
and can take a section and do the end however it works best
 
#18 ·
I think that that DC would be marginally effective at best. The problem is that 1.5hp is still only 1.5hp no matter what you attach the machine to. As well, a "cyclone" design is great for keeping the filters clean but it also increases the static pressure that is why most cyclone DC's are larger than 1.5hp. Grizzly makes a lot of good products but for them to pair a small hp motor with a cyclone design doesn't make sense. As well, for the price of the Grizzly DC, you could get a pretty awesome DC from Penn State Industries that would have more than enough power to keep the dust in your shop at safe levels.
 
#19 ·
This is all wrong for a small hobby shop!

If you are planning to run multiple machines (more than 2 or 3) at the same time, you'll need more than a couple of hp and should have an specialist configure/design your system to make sure it works. A small, simple system should be able to easily handle a jointer and planer at the same time using 4" pipe.

First, you are not going to collapse metal ductwork with an exhaust fan, it simply won't happen. Those ducts are not made with aluminum foil, they are usually 26 guage steel.

Second, you need to be concerned with air velocity, not volume. The volume in those ducts will be limited by the amount of air you can suck through your machine. You will need to keep the velocity up in order to keep the dust from settling to the bottom of the ducts.

Just a hint of things to be aware of… look at the second picture above (wow, it's pretty!), whenever that jointer runs much, if not most of the chips will be dropping/falling down the next branch pipe, right into the planer (all of the branches should be teeing off to the side). Also, you don't need to spend a lot of mony on wyes, just keep the pipe size small (keeping the velocity up) and use the much cheaper tees.

For my 2-car garage shop I've got a 1100 cfm Jet with 2 main branches and it works great. I could/should have gone with half that size. I have a single 6" ell mounted to the blower (to open the blower throat) which redirects the ductwork to the wall. From there I put a single 6" tee with 2 6" to 4" reducers. I've run all of my main branch ducts in 4" pipe, using simple tees for the machine branches. I bought everything from Home Depot and it works great and was very reasonable in price (and nothing is close to collapsing).

Good luck
 
#20 ·
Just a hint of things to be aware of… look at the second picture above (wow, it's pretty!), whenever that jointer runs much, if not most of the chips will be dropping/falling down the next branch pipe, right into the planer (all of the branches should be teeing off to the side).

Had not thought about that, I will have to test that out!
 
#22 ·
I taught night classes in a technical school about 30 years ago. They (the school ) installed a dust collection system. It was probably installed by the A/C people across the hall. One evening we were sweeping up to go home. There were 2 floor sweep ports to sweep the chips into. One of the guys closed the lid on the floor sweep. This lid closed at an angle so the weight of the sheet metal lid held it close to the box we swept into. The system was on and running. There were no open blast gates except to this floor sweep. Boom!! we had about 20 feet of supported metal pipe sucked as flat as a pancake. That pipe had to be replaced. I don't know what gauge the pipe might have been. I just know it was a couple of weeks later when they got the pipe replaced. I was more careful to tell them to keep things open until the collector was shut off. Pipes can be flattened by a vacuum.
 
#25 ·
The duct you can get at the big box stores was never intended to be used in DC systems. The gauge is only 26 gauge while the heavier DC duct is 23 gauge. I'm not saying the thinner stuff will not work, but you are taking a risk of having the duct collapse if all the blast gates are closed.
 
#26 ·
MrRon…a good friend is in the commercial HVAC/plumbing business and I asked him about it months ago. He said that NO commercial application would allow the thinner stuff. If you know such a person that has access to the commercial wholesale houses, I think anybody will find that the price is comparable.
 
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