Duct Size for a Harbor Freight Collector

[Fred Morina]

Hi everyone. Just a “weekendwarrior / hack” here. I was hoping youcould give me your opinion on a proposed setup for my small garage workshop….specificallythe proper duct size to use. Afterlooking at countless threads I’m still having a hard time nailing this piecedown. Like many hobbyists, I have a 10year old stock Harbor Freight unit that I’m upgrading. For what it’s worth it’s “rated” at 2HP and1550 CFM. I just purchased a WynnCartridge Filter and the 5” Super Dust Deputy. I anticipate streamlining the configuration of the unit to mount theintake directly on top of the SDD, but with little or no flex hose in anattempt to maximize the air flow. Knowing that I’m still looking at aninvestment in piping, blast gates, etc., I’m up against the wall as far as anyfurther upgrades to this HF unit.
I intend to have most of my machines grouped in the centerof my workspace (along with the dust collector), so my goal is to have a veryshort main intake trunk line…perhaps 6’- 8’ once the duct coming from the SDDreached the floor.
Since the SDD comes with a 5” intake port I’m leaningtowards a 5” main trunk line. Whatever Idecide to use I’d also like to maintain that size all the way to my machines ifpossible. From what I’ve been reading Ibelieve I should definitely stay away from 4”, but I’m concerned about going toa 6” main with an under-powered HF unit.
I’d appreciate your thoughts… Thanks!

[Roy Petersen]

I have that same setup (but had used 4" PVC for a long while, and it wasn't good).
As the inlet to the SDD was 5", that's what I went with, but there's a scarcity of 5" PVC around here, so went with heavy gauge (24) metal from Oneida. Small shop, roughly 20' square, so stuck the "head" of the DC up in the attic, and piped it straight down to a corner of the shop. The outfeed blower goes into 5" also, makes a turn and into the canister filter in the next room (need quieting still). Ran the 5" inlet run along one wall to the first station, then across to the second drop, from there to the far end drop. Roughly 10' between drops. Used the 5" all the way to within a few feet of the station, wide radius 90's, and blast gates right at the end of each drop.

Testing (non-instrument) shows great flow and material movement is adequate to keep things moving and not plug up. Nothing appears to drop out of the stream from any of the tools (largest producer is the table saw).

[Art Mann]

Actual measurements by magazine reviewers and knowledgeable individuals suggest the flow rate of a typical HF based system is 400 to 600 cfm. The 1550 cfm HF rating is phoney. You can't get that kind of air flow from a name brand 3 hp cyclone system once the duct work is hooked up. The filter cartridge will help but the fan diameter is just too small. I would not use duct work any larger than 5" and I would use the shortest and straightest runs and the fewest number of fittings possible.

[Jim Becker]

I agree with sticking to 5" duct. 26 gage "stove pipe" is a reasonable cost product to buy and is available from most home centers, albeit not generally in the longer 5' lengths. Local HVAC supply, if they will sell to non-trade, is a good source for this, too. Adapt to 4" at the tool, if that's what the port takes.

[Peter Kelly]

5" all the way, vent outside if it's an option. I'd also recommend the 12" impeller from Rikon.

https://i.imgur.com/GK0E55r.jpg

[Patrick Cosentino]

I have that same setup. You don't want to go above 5" , the SDD inlet is the limiting factor.
I'm going with 5" steel duct for the main line.

Warning : finding 5" fittings and connectors is going to be a pain , hope you have amazon prime.
I'm currently in the process of mix and matching plastic and steel connectors

Also , i measured 960 CFM right at the 5" intake of the HF DC (removed the metal cross bar that connects it)

I'm waiting for a back ordered Rikon 12" impeller , to upgrade it as well , to hopefully improve it a little more.

Good luck , post pics when you can!

[Fred Morina]

Thank you all for your posts…I appreciate your input.
A quick follow-up question if I may…If at some point intime I decide to replace the stock HF impeller with a 12” Rikon impeller, am Istill okay with the 5” duct system?
I’mjust trying to limit the number of mistakes on a single project…lol.

[Fred Morina]

960 CMF with a stock HF impeller? From what I’m reading that soundsimpressive. Is that reading with afilter? If so, what type?

I was hoping to go with 5” HVAC piping which is readilyavailable, but I’ll need to take a closer look at the fittings andconnectors. I don’t look forward to playingaround with 45 degree saddles that I would need to attach to the main trunkmyself…That idea has a trip to my local emergency room written all over it J

[Patrick Cosentino]

Honeslty , I don't remember if it was the stock 30 micron bag , or my aftermarket 1 micron bag https://www.amazon.com/gp/product/B005VSAP74/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
The wynn filter is on my list , and should increase airflow slightly as well.

Keep in mind that was RIGHT AT the impeller.

As soon as i connected my Super Dust Deputy , (via a mickey mouse 10' HF hose ) , the CFM's dropped down to 625ish (right at the intake of the SDD)
and down again to 600 with 9 feet of 5" steel duct applied. It was at this point , that my hooded sweatshirt drawstring was sucked into the Digital Anemometer and the mini fan shattered. So all testing stopped.

Bought another Digital Anemometer to test it again , but I broke the HF impeller prying it off , so i'm waiting for the Rikon replacement until I can do anything dust collection wise. I swear my journey into dust collection is cursed. Mostly my fault ;)

Here in New England , I can get 5" pipe easily anywhere , and maybe adjustable elbows , but other than that , everything else is pieced together from online orders or specialty HVAC suppliers that want to charge a fortune.

[Patrick Cosentino]

Yes . The maximum 5" duct is limited Super Dust Deputy inlet.
If you keep everything the same , and just upgrade the impeller, it will only help things

[Larry Frank]

The numbers people are reporting are high and much higher than well run tests. People should read the March 2008 article in Wood Magazine. About the best you can get is around 600 cfm and with the SDD you will get less.

[Patrick Cosentino]

The numbers people are reporting are high and much higher than well run tests. People should read the March 2008 article in Wood Magazine. About the best you can get is around 600 cfm and with the SDD you will get less.

That's a good point. Fred (OP) you said your HF was 10 years old (Which is probably the one tested in the 2008 article). If you have the stock 30 micron cloth bag on the bottom , switch that out for a nonporous plastic bag. HF stopped using those bags after the test was run.
That , plus your Wynn Cartridge Filter , your removal of the impeller transition (by putting the DC on top of the SDD) and using 5" duct , you'll have much better performance than the stock test shows.

[Peter Kelly]

A stock (new) HF collector with the bags on should pull 885 CFM measured exactly at the 5" port. With all the mods on my one shown above, I get just under 775 CFM at the end of a relatively short 5" run, blower vented outside.

Perfect setup for a 144sq ft shop with a 5-function machine.

[Larry Frank]

Out of curiosity, can you provide the source for the 885 cfm. I have some difficulty with the number on a less than 10" impeller

[Peter Kelly]

I checked the airflow of the unit shown above when I first bought it prior to the final assembly and my anemometer gave me 33m/s at the 5" diameter port. Completely stock setup.

[Peter Christensen]

Peter were you using a fan driven anemometer or hot wire type? Fan driven ones are reputed to read much higher than actual.

[Peter Kelly]

HoldPeak vane type one.

[Larry Frank]

They give notoriously high and unreliable values. The HF is just not capable of those values.

[Fred Morina]

I mush have gotten the newer model after that article. Mine came with a 5-micron filter bag.
How long have you been waiting for the replacement impeller? That will probably be my next investment once I get the system assembled. As long as I know I will stick with the 5" duct system, I can proceed.

[Fred Morina]

Thanks again to everyone for their comments...some good ideas, helpful hints and pics. I feel like I have a much better handle on this moving forward. The chase for perfection is an endless one...you do what you can, and hopefully at the end of the day you feel good about it.

This dust collection project is the first of many projects to get my small hobby-shop back in shape after about a 10-year hiatus. Feels good to have the motivation again. Looking forward to chatting with you all again from time to time here on the forum.

Enjoy the weekend everyone!

[Peter Kelly]

How long have you been waiting for the replacement impeller? I had to wait about 2 months for mine, Rikon will let you know the lead time prior to ordering.

Certainly a worthwhile upgrade.

[Patrick Cosentino]

I mush have gotten the newer model after that article. Mine came with a 5-micron filter bag.
How long have you been waiting for the replacement impeller? That will probably be my next investment once I get the system assembled. As long as I know I will stick with the 5" duct system, I can proceed.

http://www.toolcenter.com/60-200-22.html


I Emailed them on Feb 10th , and received this reply


Hi Pat

Update on Wednesday was we are to have them available by the end of the month.
80 units coming in, 68 so far pre-sold

Not sure exact date they will arrive

Added my order in , and just waiting for it to arrive.

[Mike Burke]

5" all the way, vent outside if it's an option. I'd also recommend the 12" impeller from Rikon.

https://i.imgur.com/GK0E55r.jpg
I see some talk about replacing the impeller on this kind of DC.
Does anyone have a link to the replacement impeller ?
Is it a huge performance upgrade from the stock impeller ?

Thanks,
Mike

[Peter Kelly]

See the link in Patrick Cosentino's post above....

The 12" Rikon impeller is certainly an worthwhile upgrade from the stock one.

[Mike Palmowski]

Hi Peter, I am in the process of setting up my new HF Dust collector and am going to follow your setup, any chance you could provide a few more pictures? I'm especially interested in what the outside vent cap is?

[Peter Kelly]

https://i.imgur.com/4RTQtp8.jpg

Vent damper outside: https://www.famcomfg.com/products/wall-vents/dryer-vents/galvanized-wall-vent-with-damper.html
30 gallon drum and 5" adapters are from McMaster, hose and duct fittings are from Blastgateco.

Am in New Mexico at the moment, can share some more photos once I'm back at the house upstate.

[Carlos Alvarez]

5" all the way, vent outside if it's an option. I'd also recommend the 12" impeller from Rikon.

https://i.imgur.com/GK0E55r.jpg

Where did you buy those sweeps? I've never seen any like it.

I agree with keeping it 5" all the way. An early version of my DC used 4" tubing and the HF collector. It was sub-par. I found a killer deal on used 5" spiral pipe, and that upgrade made a huge difference. When we upgraded the DC, the pipe was still sufficient for the new system.

Oneida says you should never decrease pipe size on the way to the DC. That's because the air velocity is going to be limited by the smallest diameter, and you don't want to have large pipe running low velocity air.

[Peter Kelly]

Piping, fittings and hose are from Blastgate Co: http://blastgateco.com/Spiral-Pipe-and-Fittings.php

Prices are decent, sometimes they have specials on different items, just need to call them.

[Craig Stueve]

Piping, fittings and hose are from Blastgate Co: http://blastgateco.com/Spiral-Pipe-and-Fittings.php

Prices are decent, sometimes they have specials on different items, just need to call them.

Peter - Do you happen to know if the fittings from Blastgate Co will fit inside of standard HVAC snap together pipe of the same diameter?

[Peter Kelly]

I'd imagine the stamped fittings would probably work with snap lock pipe but you'd probably need to cut off the crimped parts. If you're thinking of going with the stamped fittings, spiral pipe really isn't a whole lot more money over the heavy gauge Greenseam stuff from Grainger. Quite a bit easier to work with as well imo.