What type of ductwork would you use in your DC system?

  • Advertise with us

« back to Woodworking Skill Share forum

Forum topic by DocSavage45 posted 03-11-2017 07:45 AM 3597 views 1 time favorited 26 replies Add to Favorites Watch
View DocSavage45's profile


8725 posts in 3048 days

03-11-2017 07:45 AM

Topic tags/keywords: question tip dust collection

Once again I’m mulling over “what to do” with re-configuring my dust collection? Been reading Bill Pence’s information and I went “whoa Tom!” So I thought I’ve gotten excellent accurate advice form LJ’s with experience. So I’m seeking Your counsel again…before Murphy and I screw it up!

This decision to upgrade my DC has come about from Finding my dust collection using 50 feet of 4 inch plastic sucks, but not in a good way! LOL! Watching some great YouTube videos of creative home made Thein separators (which I’ve made awhile back. Mine is a 55 gallon drum attached to my 1.5 HP Early model Delta dust collector. Have it on Craig’s List in this area (S.E. MN) and I am disappointed as I have usually sold my listing by now.

Step two is to use what I have to optimum efficiency?

Some good info re: Gannet woodworkers video and Bill Pence’s in depth information.

I was trying to use what I have which is a lot of leftover HVAC 6 inch pipe and flexible elbows with whye connectors. Thought I had this down and I was ready to commit.

Pence’s info has given me reason to pause. There are problems due to direction of the air movement and there are problems identified in stepping down to the 4 inch intakes on My 3 hp cabinet saw, 2 hp band saw and I want to provide ports for a jointer , planer, and dust collection table.

I’d only be using one tool at a time.

I had planned on using the Delta with the 6 inch opening instead of the dual 4 inch port, and adding 6 inch inlet and outlets to my 55 gallon chip collector.

Your knowledge and personal experience is welcome!

-- Cau Haus Designs, Thomas J. Tieffenbacher

26 replies so far

View Bumpy's profile


40 posts in 686 days

#1 posted 03-11-2017 11:51 AM

While I am not an expert on DC systems, I have used several over they years and in trial and error I finally have a system that works for me.

My shop is 25×40 x 16. I have a Penn State 3hp cyclone. I have just made some adjustments, removed 6” T’s and replaced with 6” Y’s. All but 2 drops are 6” with a 6×4 reducer / blast gate. The remaining 2 are 5” ending in a 5×4 reducer / blast gate Just under 100 ft of 6” HVAC metal duct around the perimeter walls.

I recently ran the 6” duct that was connected to an 7’ cartridge filter through to exterior wall with good results. Following LJ suggestions, it is reduced to 4” at the tip to assist with back pressure.

The markup on HVAC fittings at the big box stores is huge. I have a friend in the HVAC business that purchased the fittings and duct for me from a supplier. At the big box store a 5’ 6” length of duct is 9.95, buying wholesale a package of 10 5’ x 6” duct was 49.00. Fittings wholesale are about 1/3 the cost also.

For hanging the duct work, I have found that utilizing a wire staple (plastic with 2 nails) placed in the center line of the duct allows me to use a 22” zip tie to hold the duct work against the wall, it also works for the drops.

View Redoak49's profile


3671 posts in 2194 days

#2 posted 03-11-2017 12:09 PM

I feel your pain going thru this as I did it a year ago. I got a 5 HP Oneida Super Dust Gorilla and had all kinds of concerns. Oneida gave me a duct design which would not work for me. I also went thru all of the Pentz info and calculations.

My Dust collector has an 8 inch duct coming out and I ran it for a short distance and then to 6 inch DWV plastic pipe. For my cabinet saw and 15 inch planer had a 6 inch blast gate, then to 5 inch flex hose and down to 4 inch ports. I measured the flow and had over 600 cfm and did a very good job with dust collection. If it had not done a good job, I would have opened up the ports on those machines to 6”.

I did document the actual flows and static pressure for my system and it is in my blogs.

My other blogs show the assembly of my dust collector, gates I made and how I developed my own performance curve.

My recommendation is to run 6” duct and as close to your machines as possible down to 4”. If this works …great. if not, then open up the ports.

View TungOil's profile


1061 posts in 700 days

#3 posted 03-11-2017 01:03 PM

Good dust collection has to balance air velocity within the ductwork (to keep chips suspended) with frictional losses created by pipe, fittings and flex hose. These guys do a good job explaining how the design a system without getting too much into the complex engineering behind compressible fluid dynamics.

I used their hobby shop components when I put together my latest shop. Big improvement over my older system that was build with PVC and safer I think too. Importantly their fittings are all long sweep and designed for good airflow.

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

View Fred Hargis's profile

Fred Hargis

5179 posts in 2699 days

#4 posted 03-11-2017 01:04 PM

On my tools if at all possible I went 6” to the tool…this usually meant making some mods to the tools. In the case of my drum sander I made a complete new top since the one on it couldn’t be easily modified. You can quickly get swamped trying to do the calculations, my approach was to use the most (biggest) ducting I could and ease the turns as much as possible. I do have a magnehelic and pitot tube, so i was able to measure the air flow. In most cases I can get almost 1000 CFM at the tools when it’s not running (the work piece usually blocks this somewhat, I guess). One problem I ran into was my table saw, it has internal plumbing that keeps me from easily opening up the puny 4” port on the saw cabinet. But with a 3” overblade pickup I still seem to get about 1000 CFM between with both of them wide open, and most of the dust. Here’s what I did to my DS:

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

View Monte Pittman's profile

Monte Pittman

30071 posts in 2543 days

#5 posted 03-11-2017 01:09 PM

I have 6” hoses that I can move around.

-- Nature created it, I just assemble it.

View Jim Finn's profile

Jim Finn

2687 posts in 3127 days

#6 posted 03-11-2017 02:00 PM

I used 6”, 26 gauge metal duct. I made my own wyes and sealed all the duct with a brush on duct sealer. (I am a retired sheet metal worker so making the fittings was easy for me).

-- No PHD just a DD214 Website>

View JBrow's profile


1366 posts in 1125 days

#7 posted 03-11-2017 02:06 PM


If you conclude your dust collector can maintain the air velocities shown in the link posted by TungOil, I see no reason why you could not reduce static pressures by moving to 6” duct work and thereby improve performance.

When I upgraded my dust collection, I did research, as you are doing. But I went one step beyond because of the time and expense of the upgrade. I consulted several books which I found very helpful…

“Dust Collection Basics”, a short easy to read book regarding home workshop dust collection. It is available for about $7 at

“Woodshop Dust Control: A Complete Guide to Setting Up Your Own System” by by Sandor Nagyszalanczy for about $18 at


“Controlling Dust In The Workshop” by Rick Peters for about $5 at

If you elect to proceed with the 6” pipe upgrade, I suspect 6” HVAC pipe might work. But the 30 gauge and 28 gauge metal straight might be too weak to handle a more powerful dust collector, should you later decide to buy a more powerful dust collector. I elected to use SRD35 PVC sewer and drain pipe because it was locally available, not as costly as heavy gauge metal pipe, and was easier for me to cut and fit. An advantage to PVC pipe is that it can be slightly expended or shrunk with some heat to marry to blast gates and other odd fittings. But since you apparent dislike PVC, I found that KenCraft offered a variety of fittings and pipe at completive prices.

I had several machines with a single 4” dust port. My collection system was run with 6” pipe. Wanting to add greater dust collection at the tool I elected to add a second 4” dust port. I then used a 6” x 4” D/C Adapter, which brought a pair of 4” lines directly to the 6”. This resulted in a reduction in volume of about 10% and thus avoided the about 40% reduction from using a 4” x 4” x 4” wye and a 4” X 6” reducer. However, wherever I could I used the 6” machine port.

Your upgrade may require some 6” flex hose. I found “smooth wall” flex hose by Flexaust. The company makes several flex hoses for wood dust where the interior walls are far more smooth and thus reduce static pressures otherwise associated with standard flex hose. Some of the flex hoses are advertised to dissipate static electricity, but these hoses are priced at a premium. All their hoses are more costly than standard flex hose and can be found on Amazon.

View doubleDD's profile (online now)


7902 posts in 2248 days

#8 posted 03-11-2017 02:31 PM

I’m with you Doc, read and learn.

-- Dave, Downers Grove, Il. -------- When you run out of ideas, start building your dreams.

View DocSavage45's profile


8725 posts in 3048 days

#9 posted 03-11-2017 08:01 PM


Reading is only half the battle. Money, time and efficiency are big factors for me. I’d go with a Grizzly or shop fox 2 hp single stage but Penze says 3 hp minimum? I have metal duct left over, tools etc when I installed my forced air heating. Went looking for 6 inch plastic and the price for 6 inch was amazing.

I have set up a space outside my shop. Actually planned that. LOL! A Long time ago. And my working area is about 12 by 26 ft with the table saw, band saw, lathe, jointer, and surface planer in that space. I built an add on within the boundaries of my property and the city’s right of way. My drill-press, compressor and 4×3 ft belt sander is in that room.

Finances are my real limit now. So I will take it all in and “do something!” LOL!

-- Cau Haus Designs, Thomas J. Tieffenbacher

View DocSavage45's profile


8725 posts in 3048 days

#10 posted 03-11-2017 08:50 PM


Will look into your suggestions. I had bought a bunch of 4 inch pvc adaptors etc plus 4 inch blast gates aluminum, but I was totally ignorant about pressure /flow and cfm. The reason I have a new Central Machinery dust collector sitting in a box next to my delta.

There are many technical factors to consider and get my head around. I use an air filter, and I have resperators, but I am also getting dust in the shop. I hope to amp up my building time, and I do not want to be fixing my screw ups due to making an uninformed decision.

I also know there is a down side to everything. LOL!

Thanks! I have looked at one book and the web site for metal fittings so far.

-- Cau Haus Designs, Thomas J. Tieffenbacher

View DocSavage45's profile


8725 posts in 3048 days

#11 posted 03-11-2017 08:51 PM


How big is your dust collector? HP?

-- Cau Haus Designs, Thomas J. Tieffenbacher

View DocSavage45's profile


8725 posts in 3048 days

#12 posted 03-11-2017 08:53 PM


How big is your dust collector? HP?

-- Cau Haus Designs, Thomas J. Tieffenbacher

View DocSavage45's profile


8725 posts in 3048 days

#13 posted 03-11-2017 08:53 PM


Thanks sent you a sheet metal question by PM.

-- Cau Haus Designs, Thomas J. Tieffenbacher

View DocSavage45's profile


8725 posts in 3048 days

#14 posted 03-11-2017 09:00 PM

Tung Oil,

Looking at the web page. Thanks!

-- Cau Haus Designs, Thomas J. Tieffenbacher

View DocSavage45's profile


8725 posts in 3048 days

#15 posted 03-11-2017 09:05 PM


Thanks! I’ll check it out. need information!!!!!

-- Cau Haus Designs, Thomas J. Tieffenbacher

showing 1 through 15 of 26 replies

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics