6" dust collection pipes

The famous website on dust collection is adamant that you should use 6" ducts from the collector all the way up to your tools, then reduce down to 4" to get into the tool. He says this allows you to get the full capacity of a dust collector, if its 1.5 hp or greater. My dealer swears I should use all 4" ducts and it will be fine with a Jet DC1100 or greater. My shop is 3 car garage and he's been out here and has some idea of the pipe network I would need for dust collection.
The jet book on dust collection recommends a 6" main pipe with 4" branches going to the tools.
I'd like to hear the real-world experience from some of you that are running 1.5 - 2 hp dust collectors.
By the way, can anyone tell me what difference I might observe between the jet 1.5 hp and 2 hp collectors? The published specs are 1100 cfm and 1200 cfm. I would suspect the larger collector could achieve its capacity through a more complex or restrictive pipe system.
Are there any other brands you might recommend? The Jet models seem to be the most for the money in the $400-$500 price range. Others that use cartridges seem to be in the $800 up price range.
Bob
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I've got 4 inch DWV PVC clear to the 1100 DC in my big 'ole garage, with a few 90 degree bends thrown in. Total run from the furthest machine is better than 60 feet. Plus the garbage can cyclone. It sucks just fine in my one-man shop.Tom>Subject: 6" dust collection pipes

Someday, it'll all be over....
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On Sun, 23 Nov 2003 04:13:52 GMT, "Bob Davis"

I use the Penn State 2HP cyclone, with 6" thinwall PVC everywhere right to my blast gates,at which point I drop to 4" flex for the last 4 feet or so to my machines. I am totally happy with the performance of my system, although I just eyeballed the design and have never taken any performance measurements. I also took the trouble to do each of my 90 degree bends as a pair of 45's. After living with the thing for a couple of years, I never get clogs and the system seems to work really well, with plenty of airflow to occasionally send chunks of wood and such back to the cyclone for my musical entertainment.

Tim Carver snipped-for-privacy@twocarvers.com
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snipped-for-privacy@earthlink.net says...

Take a look at the spreadsheet on that site, then do some computations with your setup. Be sure to use the dust collector volume vs. static pressure drop curve for your dust collector. I have a 2 HP system, and 5" pipe is the optimal size for the pipes, 4" has too much static pressure drop, 6" doesn't get the flow rate up high enough. I used to have the system hooked up with 4" flex duct -- I never had a clog and it always sucked up the chips, but... When testing my 5" system, I understand now what static pressure drop really does to a system; although my 4" system on the table saw would clean up the chips, I could actually see the system pulling in dust through the blade insert with the 5" system -- it looked like one of those Jenn-aire range hood commercials. When you use the curve I indicated above, the process on that spreadsheet will be iterative, you will have to find flow volume, check the pressure drop, then adjust the volume input until the volume and drop intersect on the chart.

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Thanks for the feedback. The site is much better organized than when I first looked at it. I've printed out the whole site, downloaded the spreadsheet, and I'm reading and learning tonight.
Your qualitative description of the differences is inspiring to do it right.
Bob

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On Sun, 23 Nov 2003 04:13:52 GMT, "Bob Davis"

2HP is rather on the borderline. I'd go with 4" though, because 6" on an underpowered DC fails more drastically than 4" suffers through friction. If your workshop is big enough that you need 6" because of run lengths, then make sure then fan is big enough !
If I was plumbing in a whole workshop from scratch, then I might do a shared roof-level backbone in 6", but I'd certainly do the drops to each machine in 4". Sucking vertically in 6" just doesn't work if you're at all marginal.
-- Die Gotterspammerung - Junkmail of the Gods
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Thanks for the comments, Andy. I've done more reading and looked at the charts and I am beginning to understand the give and take. I had a course in fluid mechanics in college and its slowly coming back to me.
Bob
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On Mon, 24 Nov 2003 01:56:13 GMT, "Bob Davis"

I had a course in it too. Do you still get the nightmares ? 8-)
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On Mon, 24 Nov 2003 12:09:03 +0000, Andy Dingley

Me too. I also designed hydrocyclones used in the paper/pulp industry. The knowledge and experience helped me to build my shop cyclone for cheap. With pipes, the smoother, the less turbulance and better flow.
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snipped-for-privacy@codesmiths.com says...

I never had that opportunity (EE's didn't need to take that). My nighmares come from suppressed memories of Statistical Thermodynamics. The course was taught by a professor who was mad at the world because he hadn't won the Nobel prize. Straight 90, 80, 70 grading scale with tests that were designed and had a class average of 60.
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That reminds me of the professor I had for Differential Calculus. He has never taught the class before and could not solve the problems himself Then the entire class failed the test (actually, high score was a C) he stated that he would not grade on a curve and that the whole class was stupid. Ah, the good ole days.
-- Al Reid
"It ain't what you don't know that gets you into trouble. It's what you know for sure that just ain't so." --- Mark Twain
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Ouch! ... I remember some 40 point curves in that class with a teacher who knew what the hell he was about.
--
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Mark & Juanita wrote:

My nightmare was "Signals & Systems"...taught by a professor who had never taught an undergrad class before. I recall getting a 32% on one test - and that was a 'C'. Thank the gods for a curve!
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Chris Merrill
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@christophermerrillZZZ.net says...

Yep, our linear systems class was that way also. Same average on the first test,except one guy got either a 96 or 100. I knew him and talked to him afterwards -- turns out he had failed the class the semester before so had the pre-requisite for the class (a full working knowledge of all material to be presented in the class).

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Looking back ...(I graduated in 1965) I can not recall ever using a damn thing I learned in College...... NOT A DAMN THING...
But I know ... I must have ..
I THINK !
Bob Griffiths
Bob Griffiths
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wrote:

I still use plenty of things I learned at college.
Some of them were even on the syllabus.
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================Point well taken.... lol...
Bob Griffiths
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