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Forum topic by Reaperwoodworks posted 02-18-2016 07:21 PM 812 views 0 times favorited 24 replies Add to Favorites Watch
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Reaperwoodworks

94 posts in 398 days


02-18-2016 07:21 PM

Topic tags/keywords: dust collection pipes

Hey everybody, I think I’m up in my own head about this problem. So, I’ve decided to ask for some input.

I’m getting ready to install a brand new 3HP dust collection system in the shop. I got this one from Grizzly

So, it has a 7” inlet port, which has a 3 way splitter to 4” pipes. I’m going to toss that adapter right from the start. I’m set on getting a dust deputy cyclone. It has a 6” outlet, so I’m guessing I’ll get a 7” to 6” reducer, that will feed from the outlet of the cyclone to the collector.

My next question, and really where I’m stumped…should I run 5” pipe to all my machines, then step down to the 4” as close to the machine as possible, or better to just run 4” from the cyclone and get a 5” to 4” reducer? I know running the 4” pipe will be a lot easier, and probably a ton cheaper. Am I going to lose out on that much suction just running mostly 4” pipe? Seems like that’s what I see most people doing but for some reason this is driving me nuts.

I’m going to have gates at every tool, so I’ll only have open what I’m using. And my run is really going to be one long run with only 1 turn close to the cyclone that will feed another branch that is a straight run also.

Any helpful info would be great!

Thanks everyone.

-- Website: www.reaperwoodworks.com, Youtube: https://www.youtube.com/channel/UC_ognomZyK6V0VwdokBcixw


24 replies so far

View AandCstyle's profile

AandCstyle

2571 posts in 1721 days


#1 posted 02-18-2016 11:34 PM

Reaper, I am not an expert, nor did I stay at a Holiday Inn last night. However, IMO, the goal of a DC is to move as much air as fast as possible to collect the most dust. Toward that end, I would run 7” duct for 5-10 feet from the DC to ensure the air flow is as uniform as possible. Then drop to 6” duct and run it as close to your machines as possible and reduce to 5” flexible tubing and finally to 4” at the machines’ ports. Be sure to use a long 90° bend or two 45° elbows separated by a foot or so. HTH

-- Art

View JeffP's profile

JeffP

573 posts in 856 days


#2 posted 02-19-2016 12:35 AM

Just thinking out loud here…

The cross sectional area of a 4” pipe is about 2 squared times 3.14 = 12.5 inches
The cross sectional area of a 7” pipe is about 3.5 squared times 3.14 = 38.5 inches

At first blush, having triple the cross sectional area might sound like an awesome thing. Keep in mind though, that the CFM is determined by the whole system. The air speed at any point in that system is a simple relation of the CFM and the cross sectional area (ignoring turbulence). That means that the airborne chips and chunks from your jointer or planer are going to experience a 3 down to 1 reduction in air speed as they make their way through the system described above. Air speed is what keeps airborne particles afloat…no speedy, no floaty.

So, if clogging is important to you think like this:
1) going big down to small will lead to clogs for the obvious reason of things getting pinched down into a smaller space and “clotting” for reasons of “togetherness”
2) going medium down to medium (in other words, 4” start to finish) keeps the air speed up and does not create a “choke point” as in 1 above
3) going medium up to huge obviously avoids choke points, but suffers the side effect of gradually deteriorating wind speed from source to destination.

Will method 3’s deteriorating wind speed cause clogs? Idunno. Try it and let us know. :)

BTW, I missed a meeting…where does the Holiday Inn joke come from? I’ve seen it in a few places recently but missed it’s inception. tnx.

-- Last week I finally got my $*i# together. Unfortunately, it was in my shop, so I will probably never find it again.

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Reaperwoodworks

94 posts in 398 days


#3 posted 02-19-2016 01:36 AM

Thanks for the input fella’s. I think the Holiday Inn joke is from some of their advertising?

I like your explanation of things JeffP. I think I’ll do what most everyone seems to do and run the 4” all over. Keeping the airflow speed up makes the most sense. I hope this machine is powerful enough to pull debris from the planer and jointer. Those 2 machines are going to be the closest to the collector, so I’m hoping that will make a difference.

-- Website: www.reaperwoodworks.com, Youtube: https://www.youtube.com/channel/UC_ognomZyK6V0VwdokBcixw

View Dave's profile

Dave

141 posts in 2661 days


#4 posted 02-19-2016 01:44 AM

Since air is basically incompressible under these conditions the airflow will be almost completely determined by the smallest diameter along the flow anywhere between the tool and the impeller itself. A larger diameter pipe in between could fractionally help airflow but will mostly just lower the dust velocity and risk creating piles of sawdust in your horizontal runs. The question to ask is whether you want to enlarge the port at the machine. If not, you can stick with 4” but you probably won’t get enough airflow for good fine dust collection.

-- "I'm not afraid of heights. I'm afraid of widths." - Steven Wright

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Reaperwoodworks

94 posts in 398 days


#5 posted 02-19-2016 01:51 AM

Dave, do you mean the port at the dust collector, or the machine making the dust? The port on the DC is already 7”.

-- Website: www.reaperwoodworks.com, Youtube: https://www.youtube.com/channel/UC_ognomZyK6V0VwdokBcixw

View JBrow's profile

JBrow

818 posts in 384 days


#6 posted 02-19-2016 02:50 AM

Reaperwoodworks,

Setting up a central dust collection system is a time consuming and expensive project. Therefore, taking the time and wading through info regarding effective dust collection is, in my opinion, time well spent. Otherwise, after it is all said and done, that powerful Grizzly may fail to perform as you may have hoped.

The manual that accompanies your dust collector recommends the book “Dust Collection Basics”. I have read this short book and found it helpful and understandable. Also, as I am sure you have seen, the manual itself discusses effective central dust collection system design. Bill Pentz has an extensive web site that covers probably all aspects of dust collection. In short, time is spent studying these resources before building out a system, will, I think, increase the chances that the system will work well and be able to handle the jointer and planer.

To answer your original question regarding increasing pipe size as the pipe gets closer to the dust collector it seems AandCstyle has it mostly right. However, he suggested a 7” pipe at the collector. The manual depicts a 6” line at the collector. Otherwise Grizzly’s design is consistent with AandCstyle. I would follow Grizzly’s recommendations wherever I could.

View Reaperwoodworks's profile

Reaperwoodworks

94 posts in 398 days


#7 posted 02-19-2016 03:33 AM



Therefore, taking the time and wading through info regarding effective dust collection is, in my opinion, time well spent.

“Dust Collection Basics”
- JBrow

Thanks JBrow! I couldn’t agree more! I think I’ll pick up that book tonight on google books and give it a read through (or 2). I’m in no rush to do this just to get it done. I want it done right and done right the first time. Thank you very much!

-- Website: www.reaperwoodworks.com, Youtube: https://www.youtube.com/channel/UC_ognomZyK6V0VwdokBcixw

View JeffP's profile

JeffP

573 posts in 856 days


#8 posted 02-19-2016 12:13 PM

Interesting to me that the Grizzly apparently comes with two contradictory accessories:
1) a 7” to 3 4” splitter designed to hook directly to the DC
2) a manual that suggests not using their splitter.

Perhaps they intend the splitter for use in a mobile setup where the DC sits between 3 machines. Just seems an odd contradiction.

-- Last week I finally got my $*i# together. Unfortunately, it was in my shop, so I will probably never find it again.

View Fred Hargis's profile

Fred Hargis

3940 posts in 1957 days


#9 posted 02-19-2016 01:11 PM

It’s really interesting to me that folks buy a kick ass DC, and then choke it down to the point where they could have got by with a much less powerful unit. After checking the book you should find that the 4” isn’t what you want on that DC, either in the ducts or the ports. With that unit, running 6” all the way to the tool would be a pretty good setup. There are a few tools where opening the port to 6” (like some of the newer tablesaws with internal plumbing, some drum sanders, etc.) is very hard or impossible to do, but pretty much you want as much air flow as possible so it’s worth the hassle (IMHO).

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

View Reaperwoodworks's profile

Reaperwoodworks

94 posts in 398 days


#10 posted 02-19-2016 03:54 PM

For me it was bang for my buck Fred. Im still researching. If running 6” pipe will get me better collection, I’m all for it.

-- Website: www.reaperwoodworks.com, Youtube: https://www.youtube.com/channel/UC_ognomZyK6V0VwdokBcixw

View Fred Hargis's profile

Fred Hargis

3940 posts in 1957 days


#11 posted 02-19-2016 04:12 PM

I understand completely, that was kind of my point (maybe not so clearly made). Best of luck with your efforts!

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

View WoodES's profile

WoodES

36 posts in 1155 days


#12 posted 02-20-2016 06:34 AM

I have the 2hp grizzly with a 6” inlet and didn’t use the 6” to the 4” splitter. I ran 6” PVC drain for all of my trunk and branches then switched to 4” at the machine. Before the DC, I have a Thien separator which drops the vast majority of the chips and fines. I have very little getting past the separator. My longest run is about 35’.

It seems to work fine unless I have a heavy chip load from the planer and I am thinking about trying trash can separator at the machine to drop the heavy chip volume out of the air flow before it gets to the trunk line.

Your 3hp is the run isn’t exessive should aleviate the heavy chip volume.

One thing to keep in mind. DC differs from other duct systems such a forced air (e.g. forced air heating and cooling). These drop sizes as branches come on line to maintain a similar pressure at each outlet. There are multiple branches and outlets on a trunk liine. DC differs from from this as you typically only have one outlet open at a time. Thus, keeping the duct size uniform with minimal change in size between the chip source and the DC is the way to go.

BTW, this is one of the few projects when more it sucks the better….

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Reaperwoodworks

94 posts in 398 days


#13 posted 02-20-2016 07:34 AM



I have the 2hp grizzly with a 6” inlet and didn t use the 6” to the 4” splitter. I ran 6” PVC drain for all of my trunk and branches then switched to 4” at the machine. Before the DC, I have a Thien separator which drops the vast majority of the chips and fines. I have very little getting past the separator. My longest run is about 35 .

It seems to work fine unless I have a heavy chip load from the planer and I am thinking about trying trash can separator at the machine to drop the heavy chip volume out of the air flow before it gets to the trunk line.

Your 3hp is the run isn t exessive should aleviate the heavy chip volume.

One thing to keep in mind. DC differs from other duct systems such a forced air (e.g. forced air heating and cooling). These drop sizes as branches come on line to maintain a similar pressure at each outlet. There are multiple branches and outlets on a trunk liine. DC differs from from this as you typically only have one outlet open at a time. Thus, keeping the duct size uniform with minimal change in size between the chip source and the DC is the way to go.

BTW, this is one of the few projects when more it sucks the better….

- WoodES

Ohhh, I like that idea! Could see going with a can separator at the big chip producers (jointer and planer) and running the 6” pipe. What kind of set up did you do to step down to the 4”? Mind posting a picture?

-- Website: www.reaperwoodworks.com, Youtube: https://www.youtube.com/channel/UC_ognomZyK6V0VwdokBcixw

View GFactor's profile

GFactor

79 posts in 1063 days


#14 posted 02-20-2016 07:55 AM

Holiday Inn Joke: https://www.youtube.com/watch?v=8dOHEw8izno&index=2&list=PL1BFF58FF37246D71

-- To Steal Ideas From One Person is Plagiarism; to Steal From Many is Research…

View Ted Ewen's profile

Ted Ewen

187 posts in 531 days


#15 posted 02-20-2016 10:47 AM

Found this with a quick search:
http://billpentz.com/woodworking/cyclone/dc_basics.cfm

From my reading here, Bill is the man when it comes to DC.

-- Show us a man who never makes a mistake and we will show a man who never makes anything. The capacity for occasional blundering is inseparable from the capacity to bring things to pass.

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