Dust collection duct work size

[Dave Egan]

I am looking for some advice on dust collection which most people on this forum know much more than I will ever understand. I just order a new 3HP C|Flux Laguna dust collector for my basement workshop. My current thought is to run 6" 26 gauge metal duct work to my machines and convert to 4" at the machine where ever I cannot increase any machine ports to 6". The Laguna 3HP collector has a 8" inlet (50.27 sq in) with a 4" x 3 ( 12.57 sq in x 3 = 37.71) adapter on the inlet. If I take off the inlet adapter should I use a 8" to 6" reducer (28.27 sq in) or use 8" duct until I need to branch off lines and go to 6" from that point. I will probably have 2 main branches running no more than 25'.

Any advice would be helpful. I am tired of spending money on dust collection (HF/Wynn filter/Thien baffle) only for have a dusty shop that has caused me some issues when I worked with cedar this past summer.

[Andy Giddings]

Certainly removing the adapter is a good start, as is your idea for using 4 inch only where necessary. I would also recommend using the Static Calc spreadsheet from B Pentz's website as you'll be able to see the benefits of the different duct sizes to make your choice. I have 6 inch main duct for a 1.5HP collector and have no issues so 6 on a 3HP collector will work, just might not be optimal

[James Gunning]

Dave,

Good advice from Andy. If you have a machine that doesn't readily adapt to a 6" pickup, perhaps try using a manifold to connect from multiple places. An example would be a table saw with under table and overarm collection. Picking up from multiple places to approximate the area of the 6" duct. It's important from an airflow perspective to stay with the 6" all the way to the machines if at all possible. A 4" duct will cut the airflow by more than half compared to a 6".

Look here for some ideas: http://www.sawmillcreek.org/showthre...pipe&highlight=

We feel your pain trying to parse out what works best. Most of us have had to experiment to arrive at a working solution. That can get expensive, as the costs of stuff that didn't work mounts up. We really need a sticky note (article) in this forum detailing the best practices and giving workable, not overly technical tips, about avoiding the common mistakes.

[Dave Egan]

Andy,

Thanks for the info. I will go back out to Bill Pentz's site again to find the spreadsheet. Every time I go out there I learn more and worry more about what I do in the workshop. I started out with a 10 x 10 shop with a broom and pan as a collector. Never knew that wood dust was so bad until I read the information on Bill's site.

Dave

[Dave Egan]

James,

Thanks for the link. I will probably do something like like what you did on my band saws where I do not want to cut the cabinets. The small 10" bandsaw only has a 2 1/2" port as it is. Both band saw leave a lot off dust on top of the tables and around them.

Dave

[Ole Anderson]

7" is the sweet spot between airflow and velocity. Readily available in 26 gauge snaplock.

[Andy Giddings]

Dave, I hear you - I was happy with a 1HP 5 micron cloth bag single stage originally. Thought it was normal to have a dusty shop. Another thought on duct size - as both the ClearVue 1800 and Oneida V3000 have a 7 inch inlet I would think they have been sized correctly and that Ole is spot on

[Ben Rivel]

Onieda will have all the ducting you could want/need. I would reduce the 8" to 7" right at the inlet, run a 7" main line, use 7x7x6 wyes to branch off 6" drops, then as gradually as possible reduce to 5" then 4" respectively for each tool.

[Larry Frank]

On my Oneida Super Dust Gorilla, 5 hp, I ran the 8" for several feet and then reduced to 6". For the 6", I used DWV plastic pipe and very happy with it. The air flow through the 8" and 6" was still very good.

[Ole Anderson]

And if you can't get a 6" to your machines, try for 5" which is available in both snaplock and hose. You will get a whole lot of air through a fairly short 5" pipe. My bottom connection to my TS is 5" (3" at the SharkGuard on top.) And check your local HVAC duct guys, they should do much better than any internet source after shipping is included, at least for 26 ga snaplock in 5' lengths. Odd sizes is a big advantage of steel over PVC.

[BOB OLINGER]

I have a Delta 1.5 HP dust collector; I hooked up a Thein separator. I have a 18' long 4" PVC main line with drops of 4" flex (to the table saw, to the miter saw, to the Delta 735 planer/jointer and to the separator). My question is - should I replace the 4" pvc main trunk with an 6" main, either of pvc or metal? I've never found 6" drain pvc, so would likely have to go to metal. Should I replace the 4'flex drops with 6" as well? Thanks for input.

[Andy Giddings]

Bob, if you're not getting enough flow at the power tools changing the main line and drops would give you a boost. You don't say whether your main trunk is smooth or not - I assume it is? If so, your boost is not going to be as good as changing out a long flex duct but, according to the static calc spreadsheet mentioned earlier in the thread, still around 8 in wg at 1000CFM. This boost will drop if you've got lower flow. Would certainly recommend changing both line and drops if you have the time/budget. Also go for large radius bends.

[Scott Reed]

I have the Laguna C Flux 3 on order and have the same question. It has an 8" inlet. Should I reduce at the machine and then run a 7" or 6" main duct, or run an 8" main duct for a length before reducing?

[Ole Anderson]

Reduce at the dust collector to 7" and run that as a main.

[Robert Engel]

Dave,

I would consult Laguna usually anyone who sells DC's usually has tech support or offer duct design services.

For a blower that size you may want to go 7 or even 8" mains.

Maybe someone has already mentioned this, but IMO THE most important thing I want to tell you is do NOT rely on a DC to protect your lungs. IMO there is not DC system that will totally eliminate the need for a respirator or air filtration unit when dealing with fine dust particles.

You have a good quality unit there but even if you go the nth degree ala Bill Pentz and build an OSHA compliant system (which will cost you ridiculous money) there is no better assurance for your lungs than a quality full face respirator.

For most of us "dust" collection is really a misnomer we are really looking to eliminate the dust pan and broom.