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Metal Dust Collection Ductwork Question

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Forum topic by Joel J posted 02-15-2015 04:22 PM 1530 views 1 time favorited 20 replies Add to Favorites Watch
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Joel J

37 posts in 1398 days


02-15-2015 04:22 PM

So I have decided to take the HF DC challenge and purchase one and do all the upgrades to it for my garage shop. I want to put in an overhead 5-6” main trunk with several 4-5” branches. As soon as I put a wye in the main trunk, I will put a blast gate and then flexible hose to the tool, which include TS, planer, bandsaw, 12” disc sander, drill press and miter saw. In looking at the choices of ductwork, I have found metal spriral duct, which is the most expensive but also available in 5” and 6”. Then you have PVC which is only available in 4” and 6”, less expensive but also a lot bulkier in size. So as I was trolling the aisles of HD yesterday, I saw in the HVAC section low cost metal ductwork in 4”, 5” an 6” sizes and enough “fittings” to probably do my system. Those didn’t seem airtight but with a little work I think you could make it acceptable. Can someone explain to me why this low cost round metal ductwork wouldn’t work for a small home system? Thanks.

-- Joel, Denver, CO


20 replies so far

View Rayne's profile

Rayne

470 posts in 999 days


#1 posted 02-15-2015 04:38 PM

I believe they are all 30ga and could easily collapse with the pressure of the DC system. I’m also hunting for Duct work in the 5” range to fit my Super Dust Deputy. HD has some online between Flow Master and Speedi-Products that are relatively cheap and are 26 ga, which should be suitable for a DC. I’m still hunting for the appropriate Wyes and reducers before pulling the trigger.

View Fred Hargis's profile

Fred Hargis

3925 posts in 1952 days


#2 posted 02-15-2015 04:39 PM

If it’s too thin, it can be collapsed with a larger DC. You will also find that HVAC fittings generally don’t normally come in wyes, only tees. But if you get the heavier stuff, and lots of FOIL duct tape to seal it with, there’s no reason it can’t be used. Don’t expect it (or PVC, for that matter) to fit perfectly with any connecting flex hose or other DC ports…the first rule of DC ducting is that nothing ever fits perfectly.

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

View longgone's profile

longgone

5688 posts in 2768 days


#3 posted 02-15-2015 05:00 PM

I have a good bit of metal spiral ductwork in my shop and I have combined PVC with it during different tool additions and tool relocations. I use the PVC drain pipe and have found several adapters that make a snug fit when using the plastic or metal Y connectors or other fittings. Never ever had any problem using the PVC or combo of PVC and spiral…and my big cyclone dust collector frequently runs many hours during the day.

I would go with the PVC instead of the thin HVAC metal.
The adapter fittings I mentioned were purchased through Rocckler

View john43's profile

john43

12 posts in 1583 days


#4 posted 02-15-2015 05:26 PM

I used HVAC 5” and 6” round duct for my system (3hp Grizzly two bag, two filter system) and it works just fine. No collapses after 3 years. I set it up with a remote starter which I clip onto my apron. I use Wynn filters for lots of air flow and I modified my collector to the Thien design, see picture below. ( search Phil Thien Projects on the ‘net’) Works great. FYI, I have a new, Long Ranger remote starter listed on this website for sale.

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timbertailor

1591 posts in 883 days


#5 posted 02-15-2015 06:59 PM

Most would consider the HF DC system to be too underpowered for good dust collection when trying to run plumbing across the entire shop. It has been done but is not generally recommended.

I would use 6” plumbing to maximize fine particle pick up and a 5HP+ DC, as recommended here by Bill Pentz.

You might consider building a system that services one machine at a time if you are on a budget. 4” ducting will only flow about 400cfm anyway, so it is a good match.

P.S. I also highly recommend using a cartridge filter that goes down to 1 or even 0.5 microns like john43 and I did. Small particles are the real health danger and most off the shelf systems leave a lot to be desired in this area. Factory offerings also tend to restrict flow.

-- Brad, Texas, https://www.youtube.com/user/tonkatoytruck/feed

View Jim Finn's profile

Jim Finn

2408 posts in 2381 days


#6 posted 02-15-2015 10:04 PM

I installed a six inch metal system using 26 gage HVAC duct and elbows. Boght it on line, but a local sheet metal contractor should be able to get it for you. I made my own wyes (I am a retired sheet metal worker) and blast gates. I used snap lock pipe and caulked the seam to seal it. Spiral pipe has a LOT more seam length and they leak so should be caulked. That is why I did not use it. I ran my duct under the benches along the wall thus avoiding the duct length going up and down to the equipment.

-- "You may have your PHD but I have my GED and my DD 214"

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Jim Finn

2408 posts in 2381 days


#7 posted 02-15-2015 10:04 PM

I installed a six inch metal system using 26 gage HVAC duct and elbows. Boght it on line, but a local sheet metal contractor should be able to get it for you. I made my own wyes (I am a retired sheet metal worker) and blast gates. I used snap lock pipe and caulked the seam to seal it. Spiral pipe has a LOT more seam length and they leak so should be caulked. That is why I did not use it. I ran my duct under the benches along the wall thus avoiding the duct length going up and down to the equipment.

-- "You may have your PHD but I have my GED and my DD 214"

View RogerM's profile

RogerM

757 posts in 1858 days


#8 posted 02-15-2015 10:11 PM

It works just fine. I have used it all over my shop powered by an Onedia Super Dust Gorilla. Couple of notes: Lowes offers similar ducting with a crimp every 12” which makes it much more rigid. Also, you can seal the ducting with a water based, putty like substance called Dect Seal which is offered by HD and Loews. You can also use aluminum duct tape to seal joints and seams which works nice. Word of caution, stay away from the old duct tape.

-- Roger M, Aiken, SC

View JAAune's profile

JAAune

1634 posts in 1776 days


#9 posted 02-15-2015 11:00 PM

Spiral duct is actually the cheapest I’ve found but you need to locate a nearby manufacturer who will sell to order. Retail markups and shipping raise the price a lot. In Chicago, Air Duct Manufacturing sold me 6” pipe at less than $3 per lineal foot for 26 gauge spiral. That’s less than half the cost of the cheap snap-loc I priced at Lowes.

-- See my work at http://remmertstudios.com and http://altaredesign.com

View Joel J's profile

Joel J

37 posts in 1398 days


#10 posted 02-16-2015 01:48 AM

Brad,
Thanks for your comments when I was asking about metal duct. I might go ahead and try a 6” trunk that between horizontal and vertical will probably run no more than 15’. I will set it up more as a convenience than hooking up each machine individually as I use them. I do like your “cart” and would love to see more pics.

John,
I am going to setup the HF as you have yours (and TimberTailor setup) with the Thien seperator, the cartridge filter and adding a wok between the filter and the dust bag. I would love your switch but will be running this on 110v.

JA,
30 ga. ductwork at my HD/Lowes runs about $8 for a 5’ piece in either 5” or 6”, wyes (not tees) run around $10, adjustable elbow around $5, reducers 6 to 5 or 5 to 4 run around $6. I haven’t found any spiral for anything close to that price here in Denver and online runs about $5/ft plus freight.

So, the question to those out there that have a HF DC, will this unit pull enough air through 15’ of 5”/6” metal duct and 8’ of 4” flex or am I just wasting my time and should spend my dollars putting something together like TimberTailor has done?

Thanks guys!

-- Joel, Denver, CO

View OSU55's profile

OSU55

1056 posts in 1449 days


#11 posted 02-16-2015 05:58 AM

One important thing folks miss – a lot of fine dust escapes at the cut of the machine – especially the typical machines we weekenders have. Unless one has commercial equipment with auxiliary hoods and a big ass DC, there’s plenty of stuff in the air to do you damage, regardless of what filter is on the DC. I think your plan will be fine, just keep all blast gates closed except the machine you’re running, and wear a respirator.

View Bill7255's profile

Bill7255

352 posts in 1744 days


#12 posted 02-16-2015 01:56 PM

You can search and find where 30ga has collapsed and also where people have used it successfully. I decided to run some test as I had bought 6” 30ga by accident because I didn’t know much about metal ducting. I wanted to know if the pipe would work. I was also trying make a spring operated relief when all gates were closed. I couldn’t get the right spring force to make that successful. My system is a 3hp Jet 1900. My preliminary test show that if the seams are in line with each pipe, say along the top, the pipe collapsed in my test. I put plywood rings around the pipe in this configuration and it did not collapse. My second preliminary test I oriented the seams 90 degrees (side to top) and the pipe did not collapse. I will be running a second round of testing in a couple of weeks and will post those results. This time I will try a damper style relief. This first test I only had 3 5’ sections. I will increase the number of sections. I intend to use the 30ga, but knowing I will assume some risk, but this is strictly a cost issue compared to other materials. I have about a 100’ of straight pipe and multiple fittings to install. If ionly had say 30’ I would go with 26ga. Also you will be more likely to dent the thinner pipe. None of the 30ga fittings collapsed.

Here is a picture of the pipe collapsed. Note I did not fully close the gate, about 2/3’s closed. The pipe was oval about 3” X 7 1/2”.

Here is the pipe with the plywood rings, the pipe did not collapse.

-- Bill R

View timbertailor's profile

timbertailor

1591 posts in 883 days


#13 posted 02-16-2015 02:13 PM


One important thing folks miss – a lot of fine dust escapes at the cut of the machine – especially the typical machines we weekenders have. Unless one has commercial equipment with auxiliary hoods and a big ass DC, there s plenty of stuff in the air to do you damage, regardless of what filter is on the DC. I think your plan will be fine, just keep all blast gates closed except the machine you re running, and wear a respirator.

- OSU55

This thinking is just wrong. A typical DC system is flowing 400CFM+

If you have a 20×20x10 space, the DC system will fill\replace that room with fine\really dangerous particles every 10 MINUTES of operation. The kind of particles that just don’t fall to the floor but stay airborne for many hours and will be kicked up with the slightest movement or drafts.

-- Brad, Texas, https://www.youtube.com/user/tonkatoytruck/feed

View Joel J's profile

Joel J

37 posts in 1398 days


#14 posted 02-16-2015 03:04 PM

Bill,
Great info. On the Lowe’s website, on the 24” length x 6” pipe, the description reads: 26 ga. Where it displays the 60” long pipe, it does not mention the gauge. I am assuming, before i go look at it, that it is the same. I would think the little extra material thickness might help out.

Brad,
I agree with your thinking on the fine particles. I have previously built a ceiling hung air circulator with (4) built in filters. I either blow them out or replace them every other week based upon how much I use the garage/shop. Really came in handy the last month or so when I was spraying SW ProClassic (acrylic latex) in the garage. Hardly anything ended up on the walls or the floor. Great project if you don’t already have one.

-- Joel, Denver, CO

View Bill7255's profile

Bill7255

352 posts in 1744 days


#15 posted 02-16-2015 03:51 PM

Joel
On the Lowes web the $16 pipe is the 26ga and the $7.50 is the 30ga in the 5’ sections. They normally do not stock the 26ga in 5’ sections. If you are installing wyes, you need to buy the hand crimper around $20 as you will need to reverse the direction by flattening as received crimps and crimping the opposite end. All seams should be taped with aluminum tape and joints may need to be riveted or screwed. The cost of 26ga for 100’ is $328.80 and the cost of 30ga is $149.80, a $179 difference. If you go with 26ga fittings it really gets expensive.

-- Bill R

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