Replacing 4" PVC with 6" metal for dust collection ducting--Some Things I Learned

What kind of metal pipe did you use? HVAC pipe from the hardware store?

Would you post a few pictures? I’m particularly interested in your Y-joints and the main connection to your dust collector.

-- Jeffrey

Yes, Borg metal duct.

I’ll try to take some pics, but not sure I want to show them!

What kind of metal pipe did you use? HVAC pipe from the hardware store?

Would you post a few pictures? I m particularly interested in your Y-joints and the main connection to your dust collector.

- menuisierJC

-- "Man is the only animal which devours his own, for I can apply no milder term to the general prey of the rich on the poor." ~Thomas Jefferson

I paint 2 coats of duct sealer down the length of the joint. And also on the 90’s after adjustment and installation. As short of screws as possible to avoid collect long stringy shavings. 26 or even some 24 guage when 26 was out of stock. I use 5” with my 2 hp collector.. I buy the long 90’s, but weld up my own Y fittings to order with a spot welder, then seal with more duct sealer. There are online apps with patterns for cutting the parts for a Y, or a double Y. A great system, and being steel, no shock hazzard.

I am in the process of same. That darn spiral duct is expensive. I did not use HVAC duct for the trunk as I have been warned, if you forget and all your gates are closed, you can collapse the duct. Anyway, 6 inch all the way to the TS and BS. Splitting a 4 for the sanders. Dropping a 4 inch right over the table that I can move between the router and TS blade guard. I’ll have a 4 inch port I can put my planer and jointer on. They’re on wheels.

I am a big fan of the foil duct tape. Unlike Duck tape, it is suitable for ducts as the glue does not dry out like the rubber glue does. Easier to re-do as it does not get hard like duct sealing paste or even caulk. Found my self-clearing blast gates leak quite a bit, so they will get a flap of poly tape.

Just added a ClearView cyclone to my Fein vac. Super impressed. Found adapters for my pad sanders and made one from a bit of sink trap PVC for my old Makita belt sander.

Bill Pentz says it really takes a 5 HP, and that needs at least an 8 inch trunk, but I don’t have the power. I’ll see how I do with the 1 3/4. If it is OK, then on will go with the 6 inch Oneida. If not, I’ll get a new 3 HP system.

The hard part is not the DC system, it is the various ideas I have for focusing the airflow through the TS. I was looking at the trunnion and it looks very hard to do any of my crazy ideas except the ramp.

I cut my ducts with my angle grinder. Much easier.

I am in the process of same. That darn spiral duct is expensive. I did not use HVAC duct for the trunk as I have been warned, if you forget and all your gates are closed, you can collapse the duct. Anyway, 6 inch all the way to the TS and BS. Splitting a 4 for the sanders. Dropping a 4 inch right over the table that I can move between the router and TS blade guard. I’ll have a 4 inch port I can put my planer and jointer on. They’re on wheels.

I am a big fan of the foil duct tape. Unlike Duck tape, it is suitable for ducts as the glue does not dry out like the rubber glue does. Easier to re-do as it does not get hard like duct sealing paste or even caulk. Found my self-clearing blast gates leak quite a bit, so they will get a flap of poly tape.

Just added a ClearView cyclone to my Fein vac. Super impressed. Found adapters for my pad sanders and made one from a bit of sink trap PVC for my old Makita belt sander.

Bill Pentz says it really takes a 5 HP, and that needs at least an 8 inch trunk, but I don’t have the power. I’ll see how I do with the 1 3/4. If it is OK, then on will go with the 6 inch Oneida. If not, I’ll get a new 3 HP system.

The hard part is not the DC system, it is the various ideas I have for focusing the airflow through the TS. I was looking at the trunnion and it looks very hard to do any of my crazy ideas except the ramp.

I cut my ducts with my angle grinder. Much easier.

Even HD has 45 degree Y joints. And they have a nice long taper 6 to 4 reducer.

I guess I went in a different direction. For me, it e seems like a real pain to seal the metal duct. I used 6” DWV which is not heavy and joints seal very well.

I have a 5 hp cyclone and ran 6” pipe and have very good flow and suction.

I guess I went in a different direction. For me, it e seems like a real pain to seal the metal duct. I used 6” DWV which is not heavy and joints seal very well.

I have a 5 hp cyclone and ran 6” pipe and have very good flow and suction.

- Redoak49

DWV is Drain, Waste, and Vent. That’s what I used for my 4” duct. It is much lighter than schedule 40 since it is not made to handle pressuized water. In 6” it is not overly heavy, but much heavier than metal duct.

-- "Man is the only animal which devours his own, for I can apply no milder term to the general prey of the rich on the poor." ~Thomas Jefferson

Did you lose suction at the tools when you went from 4” to 6” ?

-- Mike from Lansdowne, PA

I have a 2HP cyclone and went with 6” SDR for the straight, ceiling mount drop trunk (about 15’ long) and used some of the PVC “Y’s” for branches. You are correct about the $$, but I like the ability to dry assemble and get tight joints.

The rest of the system is 6” Borg HVAC duct (the stuff with the lengthwise seam). Nice and light weight but does require the obligatory miles of foil tape. The bends are all done with the adjustable swivel “elbows” since I have some compound angles needed for routing. Nary any signs of collapsing when I slam shut the last blast gate even though the HVAC duct is thin.

Did you lose suction at the tools when you went from 4” to 6” ?

- BigMig

As long as you have a big enough blower you will gain air flow/cfm/volume of air through the pipe. The volume of air you can move is what matters, not suction. More air flow pulls more dust in with it.

Yes, there is more involved but that is generally speaking.

-- Jeff Horton * Kudzu Craft skin boats* www.kudzucraft.com

Would you post a few pictures? I m particularly interested in your Y-joints and the main connection to your dust collector.

- menuisierJC

Here’s a pic of a wye that is on the ceiling branching off to 4” pvc drop.

-- "Man is the only animal which devours his own, for I can apply no milder term to the general prey of the rich on the poor." ~Thomas Jefferson

I originally had 6” spiral duct and split duct HVAC 26gauge metal piping. My recommendation for anyone going down this path….contact your local HVAC distributor, if you have one in your local area. Just about same price tag of BORG stores but with the lower gauge. So win-win.
I ditched all my metal ducting and went 6” S&D plastic. Got tired of the paper cuts :) And not being a HVAC professional, my crimps & joints ended up being in the 4.5”-5” circumference on certain connections (especially, Y’s).
I went all S&D because can mold, bend, custom fit with heat gun for that super tight friction fit.
Total 6” footage would be around….60’ and then transition to some 20’ 4” pipe.

-- The Carpenter Bee is derived from the Ancient Greek word wood-cutter "xylokopos/ξυλοκὀπος"