Dust Collection Ductwork

[Steve Aiken]

I'm finally getting around to starting my ductwork installation for my Dust Gorilla. A couple questions....

1. Are Spiral pipe and snaplock pipe and fittings interchangeable? I notice on the Oneida site that they have both types of pipe, but they do not seem to have specific fittings for spiral pipe -e.g. lateral wyes, etc.

2. For anyone that has used the Oneida snaplock.... is there crimping on the parts more 'delicate' than the crimping found on standard HVAC fittings? It looks that way on the online catalogue, but it's hard to tell.

Steve

[keith ouellette]

I don't know how far you have gotten or if this is of use.
I use 4" pvc waist line. I figured the cost and it was much less than metal duct and is easy to cut. 4" gate fit on it with a adhesive caulk to hold the gate on air tight. If i remember it was half the price of the items your talking about. I never got around to grounding it and have no problems as of yet wit h static charge.

[Steven Wilson]

The crimping on the Oneida snaplock pipe is fine. It is helpful to have a crimper around when you're installing stuff though. Sometimes to get a good fit you may need to add a little extra crimp to the snaplock or the fittings, but that's not unique to Oneida's material.

As for 4" pvc, why would anyone want to downgrade their installation by going with 4" PVC?

[Larry Rasmussen]

I'm reading the thread because I'm planning a run of 4" ductwork and found the negative reply by Steve Wilson regarding PVC ducting to be pointless and annoying. Hopefully Steve Aiken you got your info on the crimping though, let us know how the installation goes. I'll probably still be procrastinating on mine.

Larry Rasmussen
Seattle

[keith ouellette]

I guess some people are duct snobs. It is not a down grade. It is smooth walled and is much more durable. It won't dent easy even though it is light and connections are simple and air tight with no special tools needed.

[Steve Aiken]

Are Spiral pipe and snaplock pipe and fittings interchangeable? I notice on the Oneida site that they have both types of pipe, but they do not seem to have specific fittings for spiral pipe -e.g. lateral wyes, etc. It appears that there are 2 types of wyes available - those with crimping on one end, and those without. Are the 2 types interchangeable?

Steve

[Chris Padilla]

From all the research I've seen and done, one normally comes out better going with the larger 6" pipe versus 4". Go at least 5" if you can (but PVC isn't available in 5" if PVC is your material of choice).

I hemmed and hawed for several months over metal vs. PVC and finally went PVC. Everything I have is 6".

Crimpers can be had at Home Depot (that is where I got mine) as well as other helpful/special sheetmetal-working handtools.

[Chris McKimson]

Steve,

When I got my quotes from Onieda for both snap lock and spiral for my 3HP Gorilla, the spiral quote included some necessary adapters to transition between the spiral and the fittings. That and the lack of free shipping (included with the snap lock) drove the price of the spiral up quite a bit. I ended up getting spiral from Sprial Mfg. The cost of spiral + shipping from them was less than Onieda's snap lock and I feel I got a better product. I've included a pic of one of the runs.

I'm not sure Steve was dogging PVC per se, but I read that to mean why would you want to use 4" ducting of any kind with your Oneida cyclone. I went with a combination of 8", 7", 6" and 5" and reduced to 4" only at the tool when necessary.

[Bob Genovesi]

I don't know how far you have gotten or if this is of use.
I use 4" pvc waist line. I figured the cost and it was much less than metal duct and is easy to cut. 4" gate fit on it with a adhesive caulk to hold the gate on air tight. If i remember it was half the price of the items your talking about. I never got around to grounding it and have no problems as of yet wit h static charge.

I'll have to agree with this, I did the same thing and it works perfectly. The only connections I sealed was where I installed the blast gates. It is not noisy and I have never been zapped, not even once.


As for 4" pvc, why would anyone want to downgrade their installation by going with 4" PVC?

The answer is quite simple; It Works.....

[Jim Becker]

I'm not sure Steve was dogging PVC per se, but I read that to mean why would you want to use 4" ducting of any kind with your Oneida cyclone. I went with a combination of 8", 7", 6" and 5" and reduced to 4" only at the tool when necessary.

I agree with this. Properly sized duct work is essential to maintain system performance regardless of what material it is made of. The maximum CFM you can pull through a 4" duct at typical velocities is in the neighborhood of 300-350 CFM. Stepping up to even 5", which is often an ideal drop size, will get you closer to 600 CFM. 6" moves that up closer to 700-800 CFM. And these cyclones have every bit the ability to leverage that, especially when the machine hoods are also optimized.

To the OP, in case you didn't see it, spiral will use the same wyes and laterals, but a coupler/adapter is used for the connections. The same coupler is used between sections of straight pipe. If you can find a local source for spiral, it's great stuff; otherwise, 26 gage snap lock works just fine. You can often source the straight pipe from a local HVAC supplier, too...it's sometimes referred to as "stove pipe" as that is one of its applications.

[Steve Aiken]

I'm assuming that if you used a 45 degree lateral wye or tee-on-taper designed for spiral pipe (like this http://www.airhand.com/product.asp?CategoryID=6&SubCategoryID=24) that you'd have to crimp the end closest to the dust collector. It looks like the advantage of Oneida's wyes and tees is that they come pre-crimped (http://store.oneida-air.com/item.asp?cID=0&PID=388).

I have decided that I will not be using PVC, and I will be using the ductwork plan that Oneida prepared for me to size the ducting.

Thanks for your help.

Steve

[Steve Sawyer]

I have been discussing this issue - both price and performance - with members of my local WW club.

My plans call for a 220v 2HP 1600 CFM unit, and after going 'round and 'round here's what I THINK I'm going to do - comments and criticisms welcome.

PVC S&D pipe and fittings
6" from the chip separator (might upgrade to a cyclone someday, though with 80" ceilings that might not be possible) through about 15ft of horizontal run including one right-angle turn.
6" drop to a 4" flex hose for my mobile machinery (jointer, planer, band saw)
4" drop through a wye with 4" flex hose to the TS and a 3" port to the overarm guard.
6" drop to a home-made floor sweep.As you can see I'm going with the larger-is-better philosophy. The area of the 4" TS port and overarm gaurd vacuum probably exceed that of the 6" pipe, but I'm hedging my bets by sticking with the 4" ports on the mobile machines. The chip discharge chute on the jointer is only about 4.5" wide, so I'm kinda stuck there. The port on the planer (DW735) is fixed at 4" (but has a built-in exhaust fan), and increasing the size of the port on the steel-frame band saw will require major surgery.

This is NOT going to be cheap - just the two 90 degree elbows and the three 6" wyes are going to run about $125. PVC fittings (even S&D) take a huge jump in price (about 4x) between 4" and 6".

However, I've decided that the smoothness of the surface, the ease of installation and sealing, and the somewhat lower cost make PVC a much better choice.

[Chris Padilla]

Mr. Sawyer,

That all sounds good to me but I'd take 6" as far as I could stand it. I understand that some machines are stuck at the dust port they were born with but you might try getting a taper fitting there. For my oddball 120 mm port on my MM FS-41Elite J/P, I had Oneida whip me up a nice taper for that to 6". With this, I'm necking down for about 8" or so and not several feet. Also, a taper is better than an abrupt change.

McMaster-Carr is a great source of S&D fitting for your 6" S&D: http://www.mcmaster.com/

I used two 45s to make a long right angle sweep...cheaper than the long-radius right angle.

No, this isn't cheap. Lottsa money in ductwork whether it is plastic or metal.

[Jim Becker]

Steve, you're likely to find that you're not going to be happy with a chip separator, unless it's actually a cyclone, with that DC unit...with 6" duct, the real CFM will (which is still much less than the rating from the manufacturer...;)...like half) will clear all the material from the separator anyway. You can buy add-on cyclones which will fit in your space from Oneida, etc., or build them to suit.

[Mike Monroe]

Steve A.,

Don't know the specifics of your application and I can't respond to your question re: Onieda pipe, but... I used HVAC snaplock for my cyclone piping. 7 inch main, 6 inch and 5 inch drops, home made blast gates, I had the local HVAC shop build the wyes I needed. I think I spend just under $200 on all the pipe and custom fittings, that doesn't include the coffee cans I used in making the blast gates. The set-up works great, my only complaint is there is no easy way to tell if the barrel is getting full other than to pull the lid and look.

Also, a 4" PVC waist line??? That is one skinny dude.:)

[Jim O'Dell]

I agree about using the largest pipe that you can for the major part of the ducting. That is, the largest that your collector, whether single or 2 stage will work properly with. That means not every unit will work with 6" pipe! If I had a cyclone that used larger than 6", I most likely would have used spiral. If I had known it wasn't good to use PVC where it is not visable from the shop (ie attic) I would have used spiral for at least that part. As it was, I had the PVC purchased and partially up when Bill Pentz pointed out to me that in case of a fire, it would be better to have metal in the unseeable spaces, so I had to make some major modifications to make the pipe visable from the shop floor.
I enlarged the 2 1/2" pipe for my contractor saw pick up to 6". My MM E16 bandsaw is a 100 mm port IIRC. A 4" piece of S&D PVC is a very tight fit over it, and the flex a tight fit on the PVC. I have yet to unbox the Delta 52-580 planer, but plan on following others advice and make a hood for it that , and it will have a 6" pick up, even if it makes it SCREAM. :D I have built a 6" pick up onto my router table and it works great.
I'm rambling...I guess I just wanted to make the point that not every dust collection machine out there is going to perform better with 6" pipe. Jim.

[Jim Eller]

Steve A.,

Hope I don't steal your thread. I am in the same boat, trying to figure out what to with duct work for my Oneida 3HP Gorilla.

I got the "free" design from Oneida. It all looked great until I got to the page with the $$$$'s on it. The quote was $1845.89 for snap lock pipe in a 25x30 work area. For that price I can put another Gorilla at the other end and use flex hose.

Anyway, the questions are, what are the sources for large diameter snap lock pipe and PVC and how do you transition between snap lock and PVC?

Thanks,
Jim

[Jim Becker]

The set-up works great, my only complaint is there is no easy way to tell if the barrel is getting full other than to pull the lid and look.

Sure there is...put a window in the top of the bin using 1/4" Lexan, caulk (to seal it) and screws. I've had one in mine for years. Of course, you still have to actually REMEMBER to look. :rolleyes:


how do you transition between snap lock and PVC?

Easiest way is to come out of the cyclone with 7" or 8" metal to your first branch and use metal through that point. At the branch drop to 6" and then make a little roll of metal to fit inside of PVC to create your own crimping area. Buy or borrow a crimper and do what you need to do to adapt to the metal duct. (The crimp needs to be facing the cyclone) Alternatively to crimping, make the same roll of metal and insert in the 6" PVC. Fasten in place with pop rivets or screws. Then, use a rubber clamping pipe splice from the plumbing section of the 'borg to mate to the metal duct.

[Steve Sawyer]

I used two 45s to make a long right angle sweep...cheaper than the long-radius right angle.

I've heard many do the same thing. Hate to give up that smooth curve, but yeah, those darn elbows cost a fortune...

[Brad Peterson]

Steve A.,

Don't know the specifics of your application and I can't respond to your question re: Onieda pipe, but... I used HVAC snaplock for my cyclone piping. 7 inch main, 6 inch and 5 inch drops, home made blast gates, I had the local HVAC shop build the wyes I needed. I think I spend just under $200 on all the pipe and custom fittings, that doesn't include the coffee cans I used in making the blast gates. The set-up works great, my only complaint is there is no easy way to tell if the barrel is getting full other than to pull the lid and look.

Also, a 4" PVC waist line??? That is one skinny dude.:)
Any more details? I am on the blast gates myself....

[Brent Grooms]

Do yourself a favor and look around locally.... I was given a tip on a blower supply company where I had a 7x7x7 45deg lateral (20ga) made for less than $45 and can buy spiral 6in for about $2/ft.

Often times is asking for the right product or explaining what you need accurately.

[Steven Wilson]

I'm reading the thread because I'm planning a run of 4" ductwork and found the negative reply by Steve Wilson regarding PVC ducting to be pointless and annoying.

Well Larry I'm glad you found my comments annoying. I try to make them annoying to folks' like yourself who are totally clueless.


I guess some people are duct snobs. It is not a down grade. It is smooth walled and is much more durable. It won't dent easy even though it is light and connections are simple and air tight with no special tools needed.

So Keith it's your expert opinion that Steve should run 4" PVC from his tools to the intake of his cyclone. Never mind that at best he'll get 300CFM from his machines and that his whole system will be neutured by following your asinine advice. Those with a brain choose their duct sizes to correspond with the CFM needs of their tools and the duct run they need to get from their collector to the tool. Rarely is 4" PVC (or metal) the answer. With PVC you're choices are 10", 8", 6", and 4" with 8" and 6" being the most usefull. Due to the lack of intermediate sizes you may run into velocity issues if you choose PVC, but of course you can design for that. But of course Keith Ouellete is the man and he says that 4" is all you need for whatever you want to do, anyone else is a duct snob. Thanks for you useless comments Keith and please keep displaying your ignorance. PVC isn't a problem, although it isn't as flexable as metal for designing or building your duct work, but suggesting to run 4" for everything is stupid.

[Steven Wilson]

Steve A.,
I got the "free" design from Oneida. It all looked great until I got to the page with the $$$$'s on it. The quote was $1845.89 for snap lock pipe in a 25x30 work area. For that price I can put another Gorilla at the other end and use flex hose.

Jim, Oneida is pretty good at sizing duct work based on your shop layout diagram. However, they rarely recommend changes to your shop layout that could result in much less expensive duct work. If you rework your shop layout a bit you might find that you can save a significant amount of money in your duct work. From the initial design Oneida did for me I was able to rework some items and ended up reducing my duct work costs by %40. One way I was able to save was staking up some wye's to make multi-drops (i.e. a 6" branch to a 6x5x5 then 5x5x5 wye's to get three 5" gates).

[Will Blick]

I like this concept of two 45's in lieu of a 90 deg elbow. I also like the fact it would be cheaper, but yet, when I checked the McMasters site, the cost of a 6" 45 deg. elbow was the same cost as a 6" 90 deg. elbow? What am I missing here?

Two other questions for PVC users...

1) I assume everyone is using Sched. 40?

2) I assume its best to use drain pipe, not sewer pipe?

TYIA

[Jim O'Dell]

I like this concept of two 45's in lieu of a 90 deg elbow. I also like the fact it would be cheaper, but yet, when I checked the McMasters site, the cost of a 6" 45 deg. elbow was the same cost as a 6" 90 deg. elbow? What am I missing here?

Two other questions for PVC users...

1) I assume everyone is using Sched. 40?

2) I assume its best to use drain pipe, not sewer pipe?

TYIA

Will, no the sewer and drain, ATSM 2729 thin wall gravity fed, is what to use. It doesn't have to hold pressure, and the PVC is plenty stout enough to handle the suction. S&D pipe is 1/10" thick and much lighter than schedule 40. Jim.

[Chris McKimson]

Will,

I'm not a PVC "user", but I believe that most who are using PVC for duct work are looking for sewer & drain (or ASTM 2729). The schedule 40 stuff is heavier and more expensive without any additional benefit.

Chris

[Will Blick]

Makes perfect sense.... why make it heavier than it needs to be.....

[Josiah Bartlett]

I run dust collection on my 22-580 planer. I have it mounted on a cart that is basically a plywood cube with casters on the bottom. I have a short length of 4" dust collection hose mounted from the hood to a 4" port on the box, then a 6" port on the other side of the box off to the dust collector. Since the Delta dust collection adaptor rides above the wood exiting the planer, anything bigger would rub the wood. I've never clogged it, it works great. I've even just run it for a short run without the 6" side connected and most of the chips just ended up in the box.

[Steve Sawyer]

Well Larry I'm glad you found my comments annoying. I try to make them annoying to folks' like yourself who are totally clueless...at best he'll get 300CFM from his machines and that his whole system will be neutured by following your asinine advice. Those with a brain choose their duct sizes to correspond with the CFM needs of their tools...Thanks for you useless comments Keith and please keep displaying your ignorance...but suggesting to run 4" for everything is stupid.

Steven - it seems to me that your points could be made without being rude. There are many who have systems that function adequately using 4" ducting. Note that I said "adequately" not "optimally". We're all here to share our experiences and knowledge to help one another make intelligent purchase and design decisions, most of which involve a trade-off of some kind between time, money, space and performance.

You have valid points to make that can help others make the right choice for their situation, but you devalue your own advice by being disrespectful of the advice and experience shared by others. They're not stupid, asinine, clueless or brainless - they simply have made different choices than you have, and as a result have different experiences to share.

[keith ouellette]

When i was inquiring about duct size i was warned away from using the larger pipe because of loosing pressure (or something to that effect, I can't remember the exact words). My system is a 1200 cfm and it pulls everything quite well. Is there any truth to what I was told? (I might have to get some 6in pvc)

[Jim Becker]

When i was inquiring about duct size i was warned away from using the larger pipe because of loosing pressure (or something to that effect, I can't remember the exact words). My system is a 1200 cfm and it pulls everything quite well. Is there any truth to what I was told? (I might have to get some 6in pvc)

Unfortunately, no, Keith. You're system is not going to provide it's best REAL CFM performance with the smaller duct. For a typical mass-market single stage "1200 CFM" DC, that would be about 600 CFM, give or take. 4" duct maximally can handle about 300-350 CFM tops. Duct work should be optimized to the blower of your system as well as to the individual tools.

[Steve Sawyer]

When i was inquiring about duct size i was warned away from using the larger pipe because of loosing pressure (or something to that effect, I can't remember the exact words). My system is a 1200 cfm and it pulls everything quite well. Is there any truth to what I was told? (I might have to get some 6in pvc)

I believe that the pipe diameter needs to be matched to the static pressure and CFM rating of your system, Keith.

Bill Pentz's famous website has tons of information about this. I seem to recall that he recommends maintaining a linear velocity of 800 FPM to keep chips and dust airborne all the way to the collector. If you have a blower capable of moving the air much faster than that, a too-small pipe will restrict the air flow, and could cause the that air velocity to fall below the 800 FPM rate, leading to inefficient dust collection at your machines and possible duct clogs. At the very least you're wasting a lot of power that could be better applied to sucking up chips and dust.

On the other hand, using a pipe that is too large (e.g. 6" on my little 650 CFM unit) could also cause a problem because I can't move a large enough volume of air through that 6" pipe to maintain the 800 linear FPM. In this case (and I'm just speculating here) a 4" duct might actually work better than a 6" duct.

The only way to know for sure is to a) get accurate air-velocity readings at the impeller, b) get accurate static pressure (vacuum) readings at the impeller and c) do the math to determine how small a cross-section of pipe you can use and still keep the air velocity at an acceptable value.

An alternative is to experiment - find a device to measure air velocity, attach various size pipes to your DC and see how much your ducting is slowing down the air flow.

Or, do like the rest of us - ask a lot of questions, (ignoring the folks that seem to think they're the only ones who aren't complete idiots), make your best guess, pay your money and take your chances.

[Chris Padilla]

A nice box of stuff from McMaster-Carr I got a year and a half ago. :D

Oh, and my BP/CE cyclone build I did a little while ago:

http://www.sawmillcreek.org/showthread.php?t=9933

[Mike Monroe]

Any more details? I am on the blast gates myself....

Details? Sure, two were Folgers and one was a Hills Bros. :)

Seriously though... I found plans for PVC based blast gates on Wood Central, Badger Pond, or maybe even here (I can’t remember). I used the plans as a starting point and built my gates out of ¾ ply, ¼ hardboard, and coffee cans. The blast gates are kind of like a sandwich where the ¾ ply is the bread and the ¼ hardboard is the meat. The ¼ hardboard is cut into a rectangle with a hole in one half and handles on the ends. The hardboard slides back and forth between the ¾ ply with ¼ spacers along the edges. This design is self cleaning. I also made catches/locks out of some scrap dowel. I drilled a hole in one corner of the gate in the open and closed position. With the dowel catches/locks I can lock the gate open or closed. They work great and weren’t all that hard to build. I’ve made 6, 5, and 3 inch blast gates. You don’t need coffee cans, you can use regular HVAC duct, but coffee cans are seamless and easy to hacksaw in half. I’ll try to post a pic of one with dimensions. You’ll need a pair of duct crimpers, some caulk and small screws or nails to make these blast gates.

-Mike

[Rod Sheridan]

Sure there is...put a window in the top of the bin using 1/4" Lexan, caulk (to seal it) and screws. I've had one in mine for years. Of course, you still have to actually REMEMBER to look. :rolleyes:



I had to laugh Jim, my Oneida cyclone has a length of clear flex from the bottom of the cyclone to the dust bin.

Last Sunday I was working in the shop and looked over at the flex, I didn't see anything swirling around, for good reason. I had overfilled the drum and was halfway up the cyclone! Yes you have to remeber to check.

Regards, Rod.

[Steven Wilson]

When i was inquiring about duct size i was warned away from using the larger pipe because of loosing pressure (or something to that effect, I can't remember the exact words). My system is a 1200 cfm and it pulls everything quite well. Is there any truth to what I was told? (I might have to get some 6in pvc)
By going with larger duct size you can loose velocity in your duct work and the chips/dust will fall out of suspension. The parameters you are trying to control are velocity (move the air fast enough to move the dust and chips), amount of flow (CFM), and resistance to flow (usually expressed as Static Pressure). What you use to control those variables are your Dust Collector (how much suck power you have to work with), duct size, duct length, and fittings (wye's, elboe's, etc and their physical properties). All pipe and fittings will restrict flow. The restrictions to flow will reduce the CFM available at the tool. All else being the same, smaller duct work restricts flow more than larger duct work. To overcome the effects of the smaller duct work you end up needing a very large increase in impellor size and horse power. On the other hand as you increase duct size the CFM will improve but you may end up with material droping out as your velocity drops. Bill Pentz has a nice discussion on the duct size vs. dust collector size and what seems to work the best in the introduction of his Ducting section; 5" pipe <= 1100CFM rated blower, 6" pipe - 1100CFM-1800CFM blower, 6" and larger pipe for larger systems. Instead of concerning yourself with maintaining velocity you would be better off (dust collection wise) trying to maximize CFM at the tool and only downsize pipe if you experience problems moving material.

[Brad Peterson]

Thanks Mike.

Brad

[Jim Becker]

Last Sunday I was working in the shop and looked over at the flex, I didn't see anything swirling around, for good reason. I had overfilled the drum and was halfway up the cyclone! Yes you have to remeber to check.

Better pull your filter, too, and check it. Once you get up into the cyclone, you'll get blow-by and that will pack the filter in a very nasty way. Unpleasant (and outdoor) task to un-pack it! DAMHIKT!!!

[Jim Becker]

(how much suck power you have to work with),

Just to clarify this...we generally don't refer to "suction" when working with dust collectors because they work at very low pressures...0-11" of water static pressure, or so...unlike a vacuum cleaner that sometimes gets to high pressures approaching 100" of water SP. Dust collectors work primarily by moving large amounts of air at a given velocity (measured in CFM at a particular static pressure) which you point out nicely. Maximizing that air flow without falling below the drop-out velocity is the key to maximizing system performance.

[Ken Lutes]

I used original furnace metal duct. 6 in for the main line and 4 in drops. I have have been using it for about three years now without any problems. But like most have said there are several types of material to use and I am sure they alll work fine.