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Ducting: 30 gauge vs. 26 gauge. Will 30 gauge work?

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Forum topic by Sark posted 11-13-2019 09:16 PM 559 views 0 times favorited 12 replies Add to Favorites Watch
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Sark

223 posts in 921 days


11-13-2019 09:16 PM

Topic tags/keywords: duct ducting 26 gauge 30 gauge dust collection

Getting ready to order my ducting, and I was surprised at how expensive is the straight snap-lock ducting. Oneida and others are quoting about $5 a foot for 26 gauge and Home Depot is about $2 a foot for 30 gauge. I figured that the fittings would be pricey but didn’t figure that the straight pieces would be so high priced. I’m looking at buying 30 to 40 feet.

My dust collector is 4 HP. Will 30 gauge work, or will the pipe collapse?

Another thought: What if I ran the heavier gauge to the cyclone and the lighter weight duct after the cyclone where the pressure is lessor? Final question: is there any advantage to the heavier gauge if they can handle the pressure? Less vibration? Better connection to the fittings?


12 replies so far

View fivecodys's profile

fivecodys

1530 posts in 2197 days


#1 posted 11-13-2019 09:43 PM

I went through this same exercise when building my system.
I needed 5” so using a thinner gauge was almost impossible to find where I live.
I can find 6” all day long but 5” is rare around here.
I did discover that all the HVAC wye’s are backwards so if you go the HVAC direction you will need to deal with this. I also could not find long sweeping elbows.

I am squeezing every ounce of efficiency from my system so I had to be very focused on where DC’s loose CFM’s.
I wound up using Oneida’s ducting and fittings and I do not regret the extra expense. Yes, it is expensive but you only buy it once. :)

I look forward to hearing about your decision and I hope you will follow up with some pictures and results.
I do enjoy this topic quite a bit.

Best wishes,

-- When you leave your shop for the night, make sure you can always count to 10.

View RobHannon's profile

RobHannon

322 posts in 1091 days


#2 posted 11-13-2019 09:51 PM

I am using the 30 gauge with a 2HP DC with no problem. I did install a relief near the separator. I have accidentally turned on the system with everything closed and no pipes collapsed. I did break some other things, but not the piping.

HVAC fittings being backwards is huge pain. That is the only part I think that may sway me to go another route if I were to do it again.

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Redoak49

4272 posts in 2549 days


#3 posted 11-14-2019 12:23 AM

I used 4” & 6” plastic sewer pipe. Pipe and the fittings are reasonably priced.

View pintodeluxe's profile

pintodeluxe

6015 posts in 3374 days


#4 posted 11-14-2019 02:12 AM

No, 30 gauge is no good. It’s garbage actually (think soda can).

Special order 26 gauge from Home Depot. That’s what I did, and it’s quite reasonable compared to specialty D.C. ductwork. It was almost the same price as the thin stuff. Just a couple bucks more per 5’ length.

They don’t stock it, but are happy to order it for you.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View bigblockyeti's profile

bigblockyeti

6114 posts in 2281 days


#5 posted 11-14-2019 02:41 AM

I installed thousands of miles of snap lock duct as a tinner working mostly in new residential installs. 30ga is fine but I sure as heck wouldn’t use snap lock, spiral pipe would be the only thing I would use. Despite my experience with sheetmetal, I’m still going with green sewer pipe for my system which should be about 42’ total in 7, 6 & 4 inch pipe.

-- "Lack of effort will result in failure with amazing predictability" - Me

View Sark's profile

Sark

223 posts in 921 days


#6 posted 11-14-2019 03:27 AM

pintodelux, great idea. 26 gauge from HD, never thought of that.

Redoak49, in my previous shop used 6” plastic everywhere, ClearVu cyclone and 5HP motor. It worked great. For my home shop, I’m inclined to go with metal, however. Don’t have super definite reason other than the plastic fittings were more expensive than I would have thought and heavy…and I got constant annoying shocks because the system wasn’t well grounded.

I suspect that 30 gauge spiral would be strong enough, but then you are back up in cost, I suspect. I am running 4 HP, not 2HP and the exhaust is straight from cyclone to outside the wall, without further filtration, so I think that the SP will be pretty high.

To be honest, I find the ducting design and procurement for a new dust collector system frustratingly hard…in my shop we had lots of room, machinery spread out. In my garage, I need all types of branching and blast gates close to the cyclone because the machinery is so close together.

For example of frustration, the overarm dust collector on the saw has a 3” duct so I called Oneida to see what they recommend. They recommended that I buy a second dust deputy because they don’t recommend going from 6” to 3” in a wye fitting. Really? I didn’t have enough time to argue the point, but that’s what they said. I’ve never seen a system with 2 cyclones…

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therealSteveN

4311 posts in 1135 days


#7 posted 11-14-2019 08:08 AM

Not sure where you are at, but if within their areas Menards stocks 24 guage 6”, 8”, 10, and 12, at least in the stores around me. Pretty cheap too.

I would think 30 gauge would just collapse, even on a shop vac, it’s really cheesy. Like pintodeluxe said, think coke can.

-- Think safe, be safe

View CaptainKlutz's profile (online now)

CaptainKlutz

2029 posts in 2055 days


#8 posted 11-14-2019 08:09 AM

I’ve never seen a system with 2 cyclones…
- Sark

Dual Cyclone is rare, but an example is not hard to find – Like the Grizzly G0850

It’s one way to engineer a larger system with limited mounting height. Reducing the duct velocity with multiple inlets allows for shorter cyclone. Challenge is balancing and minimizing duct loses between impeller and cyclones without growing the vertical height.

PS – Any time you want to buy (heavy/bulky) metal, look for local supplier.
Your profile doesn’t show location?
Without a location, it is hard to share if we night know about a local metal duct fabricator in your area. For me, even the most expensive HVAC duct shop near me is cheaper than Oneida duct/fittings shipped from east coast to AZ. Sewer & Drain (SD) Plastic pipe was still cheaper last time I installed permanent ducting.
YMMV

-- I'm an engineer not a woodworker, but I can randomly find useful tools and furniture inside a pile of lumber!

View ibewjon's profile

ibewjon

1066 posts in 3354 days


#9 posted 11-14-2019 11:38 AM

Plastic pipe can not be grounded. It is an insulator, not a conductor. People try to wrap bare wire or aluminum tape around plastic, but that is only decorating for Christmas. The only route it to use metal duct. Spiral pipe is nice, but hard to work with and not practical for most in my opinion. Wood magazine, which is normally a good source gave a reader a nice gift for the aluminum tape idea. Later in the same issue, there was a reference to an article about how you can not ground plastic pipe.

View Sark's profile

Sark

223 posts in 921 days


#10 posted 11-14-2019 01:01 PM

Captain Klutz, that’s perfect. I’ll use one side for the 3” overarm dust collector port and the other side for the table saw.

Ibewjon, you posted before on the virtues of making your own fittings, and I’m beginning to think that might be the best way. It’s just not the cost, per se, of ordering from Oneida or one of the other suppliers, its my complete lack of certainty that the system I’m designing will work like I want it to. As soon as I put it in, I’ll be wanting to change or modify the layout. THere’s a huge adavantage to ‘rolling-my-own.

Captain, I’ll also look into a HVAC sheet metal shop locally. There are lots of them in SoCal where I live.

View controlfreak's profile

controlfreak

331 posts in 162 days


#11 posted 11-14-2019 03:31 PM

I agree you can’t ground plastic. I wonder if using it as say the main trunk line and near the tool have a grounded blast gate or metal coupling that attaches to a anti static flex hose. This may limit the build up of a charge near the tool. I also wonder if interrupting the plastic at strategic points with a grounded metal collar would help. Or just use metal pipe I suppose. I haven’t run any pipe yet so really just thinking out loud here.

View d38's profile

d38

138 posts in 823 days


#12 posted 11-14-2019 06:29 PM

Do you have a Grainger near you? They sell Greanseam brand, and ships to store for free.
26 and 24 ga available
https://www.grainger.com/category/hvac-and-refrigeration?brandName=GREENSEAM&filters=brandName

Air Handling Systems sells a hobby line of products. I used their wide sweep elbows, and saddles on my snaplock system. Call for a shipping quote – and be sitting down—it ain’t cheap, but total coast is similar to other options.
https://airhand.com/product-category/woodworking-hobby-shop-light-gauge-solution-for-spiral-pipe-fittings-and-hose/

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