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Forum topic by gustmadeit posted 08-09-2019 02:09 AM 796 views 0 times favorited 13 replies Add to Favorites Watch
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gustmadeit

36 posts in 1727 days


08-09-2019 02:09 AM

I have a short dust collection set up and it is all 4 inch PVC however the Jet dust collector has a 6 inch inlet and I’m wondering if it would make much difference if I redid the main trunk in 6 inch? Any thoughts or advice?


13 replies so far

View Fred Hargis's profile

Fred Hargis

6310 posts in 3296 days


#1 posted 08-09-2019 10:29 AM

I would try it with the 4” and see if it does what you expect before changing anything. I would think a change to 6” would provide very marginal increases in air flow since it would still be reduced to 4” at some point in the run.

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

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Fred Hargis

6310 posts in 3296 days


#2 posted 08-09-2019 01:56 PM

I should have also mentioned in the above: air velocity needs to be a certain speed in the duct to carry the dust/chips. Depending on what DC you have (it may be worse with the smaller models) the air will slow if you put in the 6” trunk, possibly to the point where the chips fall out and cause a clog.

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

View Paul Mayer's profile

Paul Mayer

1129 posts in 3868 days


#3 posted 08-09-2019 03:11 PM

It would make a big difference, yes. The difference might be positive, but could be negative. If your DC is 1.5 HP, my guess is that the difference would be negative, and that you would drop down below an acceptable air velocity in your trunk and you would experience dust settling in the pipe, and poor collection of fine particles at some tools.

-- Paul Mayer, http://youtube.com/c/toolmetrix

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gustmadeit

36 posts in 1727 days


#4 posted 08-09-2019 06:09 PM

Yes I have the Jet 1.5 DC, and my main run is about 15 feet or so. I always wondered if I should’ve did it in 6 inch or if I should leave it in four-inch

View BattleRidge's profile

BattleRidge

150 posts in 1018 days


#5 posted 08-09-2019 06:51 PM

I have a 2hp Grizzly (6” inlet which is wyed to three 4” inlets) and ran two parallel lengths of 4” PVC (left over from another project). Each pipe has two 4” blast gates connected to flexible hose that runs to each machine. One line collects from my band saw and jointer, and the second line collects from the radial arm saw and has a length of 4” hose that I switch between my table saw, planer or for other uses as needed. I will typically only have the blast gate to the machine I am using open, but during some activities in which I am going back and forth between two machines, I will have two blast gates open simultaneously, most often one open gate on each line (hence the reason I have certain machines on certain lines).

I had originally considered eventually swapping out for a 6” line (the cost of fittings and such was the holdback), but after using the system for a while, I have been more than satisfied with the performance and have no plans on changing the line runs. I have a Super Dust Deputy cyclone that I will be installing at right before the Grizzly at some point.

I use a shop vac / Dust Deputy combo for my workbench / assembly table and drop-down area (used for the oscillating spindle/belt sander, portable router table, scroll saw, etc.) but may plumb this area into the main dust collection system in the future.

If your present system is working well, I would say to keep it as it is. If it is lacking and leaving a lot of dust and such at your machines, you could consider a change, but like others have said, the velocity through the 6” pipe might not be enough to provide an improvement and with the potential to be a detriment. I have a relatively simple set-up though and if your runs are more complicated / longer, the results could be different.

-- ~Art~

View pintodeluxe's profile

pintodeluxe

6173 posts in 3616 days


#6 posted 08-09-2019 07:04 PM

Usually once you jump up to 2 hp or bigger stationary collectors, you’ll see big improvements with 6” pipe.
Your 1.5 hp is right on the borderline, but I’ll bet it would improve collection if you went to a 6” main run, and 4” drops (assuming you only use one tool a a time).
What is the rpm and the impeller diameter on your machine? I find those stats more telling than horsepower rating.
For instance, cyclones with a 14-15” impeller do great with 6” pipe.

Good luck with it.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View clagwell's profile

clagwell

269 posts in 595 days


#7 posted 08-09-2019 07:06 PM

If we’re only talking about 15 feet of straight pipe then no, as Fred said, the increase will not be much, maybe 5% or so. As far as velocity is concerned the critical sections are those that have a vertical rise. Horizontal runs or vertical drops are not much of an issue for most types of dust other than long stringy stuff.

If you provide more information on your system I could give you a better estimate but I don’t think the difference will make you regret your decision to stick with 4 inch.

-- Dave, Tippecanoe County, IN --- Is there a corollary to Beranek.s Law that applies to dust collection?

View fivecodys's profile

fivecodys

1639 posts in 2439 days


#8 posted 08-09-2019 08:01 PM

Hey Gus,
I have the same Jet 1.5 HP blower running through an Super Dust Deputy. Oneida recommended 5” duct work for my short run system. As stated by Fred, 6” duct would probably not produce enough air velocity to suspend the dust & chips causing it all to build up in the ducting.

-- A bad day woodworking is still better than a good day working.

View gustmadeit's profile

gustmadeit

36 posts in 1727 days


#9 posted 02-12-2020 09:17 PM

This is image of my system. I’m still contemplating making the trunk 6”. I would probably raise the DC up and mount on the wall so the trunk is a straight run. Thoughts???

View d38's profile

d38

142 posts in 1065 days


#10 posted 02-13-2020 03:05 PM

1.5 HP and 4” are good combos as noted above.
You have a nicely planned system, so I’d leave it alone at this point.
A hard pipe straight into the DC is the best solution, so replace that piece of flex if you can, and you’ll get improved performance immediatly. And I read that about 6 ft straight in is way better than an elbow near the inlet.
I have about 4 ft of hard pipe straight into the DC because that’s what fit for my layout.

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gustmadeit

36 posts in 1727 days


#11 posted 02-13-2020 03:13 PM

Appreciate the insight!!

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gustmadeit

36 posts in 1727 days


#12 posted 02-18-2020 01:34 AM

View Fred Hargis's profile

Fred Hargis

6310 posts in 3296 days


#13 posted 02-18-2020 11:37 AM

You might improve the air flow from the planer is you shorten that flex enough to remove the cantenary. Of course if it’s there to let the planer move it’s all good. Nice clean install.

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

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