dust collector too weak - ugh

I just finished half of a 4" dust collecting system in my basement shop. I attached it to my 1 1/2 HP dust collector last night and was very disappointment with the results. The suction at the end of the line is weak even when all blast gates but one are closed.
The collector is as centrally located as it could be given the somewhat awkward layout of my basement. The ducts have 2-3 90s which are unavoidable given the layout.
I could upgrade to a 3HP collector and practically double the cfm. But, this would be costly.
Was it a mistake to think that a 1 1/2 HP collector would work for a system of 4" ducts? I would prefer not to roll a dust collector around when I am using the shop, but I am wondering if two 1 1/2 HP collectors (one in either side of the shop) would give better results than a single 3HP collector centrally located.
Thoughts would be appreciated.
mh
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snipped-for-privacy@yahoo.com wrote:

Are you trying to collect chips (to avoid sweeping) or fine dust (to protect your lungs)?
If you're looking to get the fine dust, then you would have been better off with larger ducts (say 6" or so). The better 1.5HP collectors can handle maybe 10-12 feet of 6" hose while still moving enough air. Anything longer distances or smaller ducts and they will no longer move enough air to do the job.
If you're stuck on the 4" ducts, then you pretty much need a LOT more horsepower to move enough air. Clearvue makes a cyclone that will do it, but it uses a 5HP motor.
Chris
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Abrupt corners drastically cut down on the air flow. I have a Jet 1100CFM collector with about the same hp rating and simply use 20' of flexible 4" hose. I attach the hose to what ever machine I am using with the flared slip fit fittings. Not a real purdy set up but it works well and well is what I was looking for. A little more trouble also but it works well and, well you know. Over all I like the flexibility and performance of the set up. Within a few seconds I can connect to my drill press, drum sander, router table, 15" planer, mobile cabinet saw, OS Spindle and 12" disk sander, band saw, and suck up debris on the floor at the end of the day.
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Three problems. 1.5hp is pretty feeble. Then the 4" is inadequate. A 3hp will help, but it won't do a great deal better over the 4" either. And of course 90s are poison. Any way to change them to two 45s?
I have the same problems and haven't decided what to do about it either. I am "planning" on getting a 3hp cyclone (JDS?) and ungrading my plumbing one of these days; but first I have to install a subpanel to handle the 3hp, so it won't be tomorrow. When I bought the 1.5hp I already had a 1hp and found another 1hp really cheap. I thought about running two 1hps, but decided it was too noisy and clumsy. Getting the 1.5hp turned out to be a mistake also, but that is how you learn.
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I have a similar set up and use 4" PVC sewer and drain. Has a nice smooth surface inside. The flex hose that accordians, will knock down the CFM tremendously so you'll want to minimize its use. If those are your long runs it will kill the CFM.
If you have a bag DC, a way to significantly increase CFM is to replace it with a filter. Bags are about 30ft2 and filter is 300ft2 so 10x less air resistance and huge improvement in CFM. Try Wynn Environmental for the some DC retrofit kits. $91 will get you a kit that can probably fit easily on your DC.

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I do have a bag DC (delta). I think a filter would be a good start and could be transferred to a 3HP DC should I take this route.
In fact (in reference to another poster) I do have pipes on the ceiling. With a 1 1/2 HP DC.
mh
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On 26 Apr 2007 07:24:29 -0700, snipped-for-privacy@yahoo.com wrote:

There are many factors that can degrade a DC system. Blast gates leak, tubing leaks, sharp turns, length of tubes, ribbed pipes, pipe diameter, etc. If there are any pipes lifting more than 4-5 feet, then 1.5 HP is just not enough. Don't even think about pipes near the ceiling unless you have a 3HP DC. Two DCs will help, but not if you have a >4 foot lift.
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SWDeveloper wrote:

Depends on the dust collector quality.
I have a Jet DC1200 w/ canister, 6" metal pipe at the ceiling, staying 6" all the way to my machines, with a trash can cyclone next to the DC. All joints are riveted and sealed with aluminum tape.
My table saw is at the end of ~ 25 ft of pipe, and has a 7' lift. All I see in the clear 6" flex pipe near the saw is a few crumbs. My DJ-20's clear flex section, at the end of 20' of pipe, has nothing at all left after shutting the DC off.
The TS drop rises at about a 70 degree angle to a wye, with the other leg connected to shop-made overhead guard, the jointer drop is a much shallower slope. I use 6" gates and only one leg at a time.
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Precicely. My DC is a Jet 1100CFM with 4", 20' of flex hose. Typically when I work close to the DC the hose makes an immediate 90 degree bend, up 7' then a 180 degree bend back to the floor.
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Barry wrote:

I have a 5" metal pipe system. When I built a trash can cyclone with 5" in/outlets my Penn State 1 1/2hp DC scours out the trash can. Believe me, I have modified every variable as to length of outlet tube and inlet angle with same results. It will only work if I reduce the 5" in/outlets to 4", then it works fine but only gets the chips. Please describe how you built your 6" trashcan separator if possible.
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snipped-for-privacy@gmail.com wrote:

I ran the 6" pipe to short 6" flex ducts to 6->4" metal reducers.
The intake comes from the ceiling via a straight metal drop and a short 6" flex. ~ 2-1/2 to 3 ft of 6" smooth walled flex hose connects the can to the DC. There is one 4" elbow inside the trashcan, on the intake side. The 6" flex hoses help facilitate emptying the can.
The can can get ~ 2/3 full before larger chips get sucked into the main DC. More smaller chips got left in the can when I had 4" pipe, but I can live with it due to the superior overall performance.
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Hey MH, Are you sure you can't replace the 90's with sequential 45's? On my initial install I had three 90's too, but after using it for a few weeks and "studying" the layout I eventualy came up with replacing all but one with sequential 45's. I'm using a 1&1/2 hp system too, 4 inch plastic pipe and 8 separate blast gates. My longest run is about 35 feet total length which sometimes services a jointer or planer or router table. Almost all of the dust and chips are sucked up. My DC is located outside of my main shop in my future sanding/turning room. I have an air return back to the main room (it's filter too). No problems with only one gate open. Sometimes when I'm routing I use two gates- one below in the table and the second on the surface. Marc
On Apr 26, 10:24 am, snipped-for-privacy@yahoo.com wrote:

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On 26 Apr 2007 07:24:29 -0700, snipped-for-privacy@yahoo.com wrote:

Air VELOCITY, not volume, is the key for sawdust and other light material. A 4" duct is waaayy too big. Prof. DC systems, like those used on floor sanding operations, use 28mm hoses for optimum results.
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LOL
wrote:

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