Suggestions to improve my ductwork layout?

R

Rushton

New member
I've received my CV1800 (with 16 inch impeller) and am now designing the ductwork layout. I'd appreciate any suggestions for how I might improve my proposed layout and have attached screen shots of my Sketchup layout.

My shop is a small basement shop with low ceilings (7' to bottom of floor joists) and has hot water heating pipes running around the perimeter about 9" below the floor joists. I'm also having to work around the furnace, hot water heater and all of that related plumping. Nonetheless, this should provide a good space for a small hand tool woodworking shop with a limited number of machines. The principal machines that I expect to use quite regularly are: Radial Arm Saw (no table saw), bandsaw, drill press and router table. I may someday add a benchtop planer, a lathe, and downdraft table for sanding. My goal is to capture as much dust as possible right at the source and minimize any micro dust particles escaping into the general air which is shared with the rest of the house.

Constraints I must work around are the heating pipes (shown as pink tubes), a water line I am not allowed to re-route (shown as a green tube), and some I-Beams that support the floor joists (the design calls for situating the CV1800 in between those parallel I-Beams with the motor sticking up between the joists). FWIW, the exhaust will be through 8" insulated HVAC flexible duct to the filter stack.

I'm trying to follow Bill Pentz's recommendations of (a) 6" pipe all the way to the machine, (b) a minimum 4 feet run of straight pipe to the cyclone intake, (c) long straight runs of duct with gentle transitions. The 90 degree elbows are all long sweep elbows with 12 inch radius (2X the pipe diameter) which Bill seems to think are good. The transition to the ceiling level main duct line (first Wye) from the straight pipe from the cyclone inlet will be a Fernco flexible coupling. All of the pipe will be 6-inch diameter PVC ASTM 2729 "Sewer and Drain (S&D)". I've chosen to go with the long sweep 90 degree elbows due to space constraints but more importantly due to the hope that the smoother walled surfaces will have less turbulence than double-45s, but I'm certainly no expert on this. I've noted bababrown's research and comments in this thread: http://www.clearvuecyclones.com/foru...bow-suggestion

Thanks for looking and for any suggestions you can share.
Rush CV1800 Ductwork Design1.JPG
CV1800 Ductwork Design2.JPG
 

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Rush,
I measured long sweep elbows in 4" PVC and found them very good in head loss. Looking at your radial arm saw I assume you do ripping as well as cross cutting. I would hold off on the precise duct design in that area until you design the hood(s) for the saw. I think you will end up with some flex there.
bababrown
 
Thanks, Bob! I recall reading your comments on your tests of the 4" long sweep elbows which is what gave me confidence to go with this design. I do use my Radial Arm Saw for ripping and also for compound miter cuts, so I will have to do some serious planning for the design of the dust hood in this area. There doesn't seem to be a perfect solution for ripping - the best I've seen so far is modifying the blade guard for a 4" flex hose connection rather the the stock 2" connection. I'd like to bring 6" into a dust shroud at the the back of the RAS for cross cutting, possibly using the "through the fence" design about which Tommy Tompkins created his Youtube video: https://www.youtube.com/watch?v=uHv3...L3vK0q6Eh7s8cP

But I'm not sure where to tap into the collection lines for 4" flex that can be attached to the blade guard when ripping. Perhaps a 4" flex drop from the ceiling along that short stretch of straight pipe between the Wye and the 90-elbow with it's own blast gate? Or, place the 4" flex connection and blast gate on the vertical 6" pipe on the wall at the back of the saw? When I open the 4" flex for ripping, I could partially close off the 6" duct leading to the "cross cutting" shroud at back of the saw to balance the air flow.

It may be that I will have build have a modular design for the RAS that allows for easy replacement of purpose-build dust shrouds depending on how the saw is being used.
 
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It appears you have a good layout considering the overhead constraints that you face with beams, pipes and ducts. I agree with using S&D PVC for your ductwork and suggest that you use a 6" x 6" Fernco coupling like this one from Lowes for the connection shown in the long straight run to the cyclone intake. It will make the gentle bend and reduce vibration. I would also recommend using clear silicone caulk at each fitting; in general, they are tight enough that they won't leak. I use the CV blast gates at the machine end of each drop and connect to 6" flex that I bought from McMaster-Carr. I use galvanized pipe hanger strap to hold my duct in the air where needed.

I also posted this over on the NCWoodworker.net forum for you.
 
Hi McRabbet, thanks for taking a look and providing me with some suggestions. BTW, I have the bin full sensor from Clear Vue that you designed and will be installing it as well.

Great suggestion to use the 6x6 Fernco coupling at the point of that bend to horizontal at the end of the cyclone intake pipe - I have one on order. I'd seen the recommendation to use one in the CV Forum and thought it made great sense.

I have clear silicone caulk for the cyclone joints but am a bit hesitant about applying it to my ductwork joints because I'm sure I will end up changing things around as I figure out dust shrouds and re-arranging machine locations. How difficult is it to pull apart piping joints once silicone caulk is applied? As an alternative for those joints that may get pulled apart down the road, I thought I'd use either flexible self-fusing silicone tape that will cut away without leaving any residue OR flexible caulking cord like this M-D caulk available at Home Depot.

When fitting the blast gates for each machine, is there any value in placing them as close to the main truck line as possible rather than next to the machine? In other words, close off as much volume in the unused drop as possible? Or does it not make any practical difference? I have blast gates for each machine that I ordered from Clear Vue with the cyclone.

The galvanized strap hangers seem to be a good simple solution. I decided to try the alternative of using 48" nylon zip ties and anchors a Bill Pentz suggested. The biggest challenge with the zip ties is undoing them to reposition. It can be done with a small probe to flip back the locking lever, but can be a pain to accomplish. But I like the ability to apply them loosely and then tighten them to get the desired fit once a row of pipe and fittings are lined up.

I'll post this reply on the NCWoodworker.net forum also.
 
Any thoughts about the use of a TRIPLE WYE in ductwork? Someone in another forum advises that a triple wye is "a real turbulence generator and should go". This person is someone whom I respect and is knowledgeable, but I'm also looking for additional input on the subject before I ditch this portion of the design.
 
I've received some good advice both here and on the NCWoodworker forum about my proposed duct layout. Based on the feedback, I've revised my design as shown below. Basically, I've shifted to a goal of using only 45 degree drops and machine connections and eliminating as many 90 degree turns as possible, no matter how formed. This means that all of my down drops will be at 45 degrees, not at 90. I've also renegotiated space in the basement with my spouse to shift the cyclone location farther to the right and along the wall behind the radial arm saw. I determined that the 6" pipe could fit along that wall behind the radial arm saw if I simply let the main duct run lower along the wall rather than at ceiling height. So, here are the current drawings.

I still have to work out connections at the machines, dust shrouds, etc. As bababrown observed, dust collection for the Radial Arm Saw will be challenging but I will first build a setup assuming cross cuts only, then figure out the strategy for ripping. For ripping, I may use another Wye to bring a full 6" pipe into position for rip cuts using a custom built shroud over the blade. The drill press and bandsaw will each have a Clear Vue 6" to two 4" transitions at the machine to support two 4" flex hoses each. All of this is still subject to be shifted further to the right (including the position of the cyclone) to allow all the 45 degree drops to land where they will need to be for machine positioning. CV1800 Ductwork Design4.JPG
CV1800 Ductwork Design4A.JPG
 
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I like this layout better than your first; one long, straight run is often better than multiple runs. My only suggestion would be to swap where your RAS and drill press are; the RAS will be the most difficult to get good capture of dust, having it closest to the DC will maximize the CFM for it.
 
Shifting the location of the RAS is a very good suggestion, Manitario. I'll take a look at the available space to make that change. A further change I made since posting this last drawing is moving the cyclone even farther to the right along that wall out of necessity to find open vertical space between the joists. The benefit of the cyclone being moved farther to the right is that it will preserve 5' of straight unobstructed pipe entering the intake (good for reducing turbulence and improving the efficiency of the cyclone I understand) while allowing that first Wye to also be to the right of that right-most ceiling I-Beam and making all the the run between the ceiling I-Beams available for machine placement..

With the RAS location change, it may then make sense to move the drill press to where the bandsaw is shown and shift the bandsaw to the left of the router table and at the end of the straight run of duct. The bandsaw is another challenge for good capture of dust, it just doesn't spray dust everywhere like the RAS and router. The drill press is less of a challenge unless it's being used for a makeshift spindle sander. Thanks for looking and commenting! Getting input on this project is a big help.
 
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I recommend checking out Frank Howarth's channel on Youtube. He has a Clearvue cyclone and has some well-designed dust collection for his various RAS's.
 
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