Another Dust Collection Question

  • Advertise with us

« back to Power Tools, Hardware and Accessories forum

Forum topic by truckman94 posted 01-03-2014 05:35 PM 1470 views 0 times favorited 25 replies Add to Favorites Watch
View truckman94's profile


9 posts in 2114 days

01-03-2014 05:35 PM

Topic tags/keywords: question planer jointer sander

Hello everyone,

I have yet another question in the wonderful world of dust collection. I have finally completed all of the plumbing for my dust collector, I ran 6 inch mains and branched off to 4 inch on all my machines. The problem is I don’t seem to have enough suction at my machines. My shop is a 40×40 and I have machines placed all throughout with blast gates to shut them off when not in use. My planer which is located about 10 feet from the collector has a 6 inch run to it and it just does not have enough suction to lift the chips and bring it to the collection drums that I have before the collector. My dust collector is rated at 2800 cfm and when it’s not hooked to the piping I have plenty of suction it just gets less as it gets away. Can I possibly install another dust collector inline along with my current one and boost my vacuum that way or what would you guys recommend? It drives me crazy having this not working right

25 replies so far

View SASmith               's profile


1850 posts in 2952 days

#1 posted 01-03-2014 05:56 PM

What dust collector are you using?
Planer shavings can be tough to collect if you are taking heavy cuts.
I have my planer as close as possible to my dust collector.

-- Scott Smith, Southern Illinois

View SASmith               's profile


1850 posts in 2952 days

#2 posted 01-03-2014 05:57 PM

double post

-- Scott Smith, Southern Illinois

View bigblockyeti's profile


5093 posts in 1686 days

#3 posted 01-03-2014 06:02 PM

More than just the air flow ability is what vacuum pressure a DC can pull. Also make sure all of your blast gates are as air tight as possible. Even if they’re only leaking a little, multiply that times the number you have and you could lose enough suction so as to not be able to keep the heavier chip in suspension as they travel back to the DC.

View DIYaholic's profile


19597 posts in 2640 days

#4 posted 01-03-2014 06:05 PM

Pictures would go a long way to providing insights to your problem!

Did you use a sharp 90° elbow, a sweeping 90° or 2 – 45° elbows with a section of straight?

How much flex hose is in use?

Do all machines have 4” DC connections, or are some reduced to 2-1/2”?

Did you tape all the seams & connections in the ducting?

Did you plug in the dust collector??? ;^)

These are all questions to be answered, before anyone can even begin to point at a possible problem/solution.

Good luck, in your pursuit to corral the dust bunnies!!! ;^)

-- Randy-- I may not be good...but I am slow! If good things come to those who wait.... Why is procrastination a bad thing?

View crank49's profile


4030 posts in 2936 days

#5 posted 01-03-2014 06:12 PM

Where did you get the recommendation to go with 6” duct.
A 6” pipe has an internal cross section area of 28.3 sq. inches.
That is about .20 sq. feet.
For 2800 CFM to squeeze through a 6” pipe it has to be traveling at 2800/.20 = 14,000 feet per minute.
A good number to design for is between 3,500 and 4,500 FPM. You are going three times that.
The higher the speed the higher the pressure required.
Or, if you don’t have the pressure, then the CFM will be reduced to the point where the system balances itself. Not knowing what your pressure rating is, or the fan size and horsepower, I would offer an educated guess you only have about 800 to 1000 CFM available on a 6” pipe; even less on a long 4” drop.

It is doubtful you actually have 2800 CFM if that is the only number given anyway. You have to have a pressure to go with that volume rating before it means anything. A fan might be rated at 2800 CFM but at open air ideal conditions. But you put a duct and a filter on it and suddenly it’s moving 1100 CFM with 5” static back pressure.

If you really do have a 2800 CFM volume at say about 10” static you should have a 10” duct and you could have four 4” drops open at the same time without degrading performance.

View Fred Hargis's profile

Fred Hargis

4954 posts in 2458 days

#6 posted 01-03-2014 06:13 PM

It’s extremely unlikely your DC can pull 2800 CFM, most factory ratings are about twice what they can actually do. Even so, that would mean you have a kick ass DC (it would help if you indicated which one it is).. So I’ll suggest it’s the size of your ducts. 4” pipe will allow 400 CFM or so at most, no matter what’s sucking on it. Changing to all 6”, even if you have to rework the machines should get you the performance you deserve. Choking down a big DC is is not a good thing. You also need to use as little flex hose as possible, I’m guessing your duct work is smooth wall pipe?

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

View truckman94's profile


9 posts in 2114 days

#7 posted 01-03-2014 06:13 PM

My collector is an oasis 1687 5hp. I have all of the blast gates shutting off and sealing good with 4 inch drops to all and no reductions to 2 1/2. All of the seams are taped to prevent leaks and the only flex I used is from the blast gate to the machine which the longest piece is probably 3 feet. As far as my duct work I used Hvac fixing with 90 degree elbows and tees. I had a tight budget when doing my duct work and this was my best route.

View truckman94's profile


9 posts in 2114 days

#8 posted 01-03-2014 06:28 PM

It’s just me in my shop so only 1 gate is used at a time also

View truckman94's profile


9 posts in 2114 days

#9 posted 01-03-2014 06:59 PM

Here are the specs on my collector

Oasis Machinery Dust Collector has 5 horsepower with an air speed of 2800CFM. This has the standard 4 inch intake and fits on almost any brand of machine that makes chips, wood dust, or debris. Motor Size: 5 HP, 220V, single-phase, 3,450 RPM, Motor amp draw: 220V – 18A, Impeller: 12” balanced steel radial, Maximum inlet size: 6”, Inlet adapter: 3-way x 4” inlets, Air suction capacity: Approx. 2,800 CFM, Static pressure: 17.2”, Bag size (Dia. x depth): 19” x 43” (lower bag), Height (with bags inflated): 88”, Bag Volume: 13.7 cubic feet, Standard bag filtration: 30 Micron, Shipping dimensions: 46” X 22.5” X 22.25”

View Fred Hargis's profile

Fred Hargis

4954 posts in 2458 days

#10 posted 01-03-2014 08:02 PM

Is that ductwork sealed? All the joints on those els and the seams on the pipe taped?

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

View crank49's profile


4030 posts in 2936 days

#11 posted 01-03-2014 08:56 PM

Sounds like you have plenty of power.
Your supplier is still jerking you around with those ratings.
With 5 hp and a 12” wheel that is the maximum CFM with no static pressure and that pressure rating of 17.2” is the maximum pressure with no flow. Also, that is the maximum pressure that fan can generate before it flies apart and would probably require more horsepower and RPM to do it. Still that’s plenty of DC for your typical shop. Following chart shows typical CFM at various RPM to get different pressures from a 5HP fan.
CFM 6.000-In. SP 1550 @3450 RPM
7.000-In. SP 1486 3500 RPM
8.000-In. SP 1464 3600 RPM
9.000-In. SP 1393 3650 RPM
10.00-In. SP 1316 3700 RPM
11.00-In. SP 1230 3750 RPM
12.00-In. SP 1131 @3800 RPM
The fan manufacturers also play with the width of the wheel instead of the RPM sometimes to get the desired characteristics.

View Bluepine38's profile


3379 posts in 3050 days

#12 posted 01-04-2014 07:52 AM

I have a 7 amp 220 volt 1 hp motor on a 10-5/8” impeller hooked to 8 ft of 6 in pipe that has 2 4” lines Yed
off it. 4 ft of 4” hose connects to a Thein separator, 6 more feet of 4” connects to my planer and I have no
trouble collecting all the chips and dust. I would say that something is not kosher with your system, just what
I have no idea.

-- As ever, Gus-the 79 yr young apprentice carpenter

View Shawn Masterson's profile

Shawn Masterson

1325 posts in 1913 days

#13 posted 01-04-2014 02:12 PM

Im leaning towards lots of leaks.

View b2rtch's profile


4851 posts in 3013 days

#14 posted 01-04-2014 02:20 PM

I looked at Oasis years ago.
It is a cheap brand made in India (I believe), I would not trust their numbers either for the motor HP or for the CFM.

-- Bert

View 49er's profile


171 posts in 1569 days

#15 posted 01-04-2014 02:40 PM

Last summer I installed a ClearVue CVmax, 5hp, with a 16 inch impeller. I have ten machines with twelve blast gates connected. I ran 6 inch plastic pipe to each machine. I have not taped any joints and I have plenty of suck. I have my planner outside, no DC to it. I just scoop the chip up and deposit them in the woods.I hope you get it figured out.

-- Correlation is not causation but I did loose my Doctor !!!

showing 1 through 15 of 25 replies

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics