Author Topic: Dust Collection System  (Read 1023 times)

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Offline Climber39

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Dust Collection System
« on: April 18, 2020, 09:01 AM »
So I'm finally getting around to finishing the installation of the dust collection system in my home shop.  No more extension cords, shop vacs, or 5 gallon buckets full of sawdust. I'm starting on it later today.  Right off the bat,  I've run into an issue.  I've been told by several,  far more experienced people,  that have all told me to keep the ductwork as straight as possible,  and to use the largest diameter ductwork possible. So, if the 2 ports on my collector are both 4 inches, would it hurt the overall performance of the system if I were to use 5 inch ductwork and a reducer? In other words,  will in the performance suffer if the diameter of the ductwork exceeds that of the ports on the collector?
I'm planning on dismantling the dust collector,  and reassembling it in a different configuration. One that'll allow me to add a cyclone separator and effectively make it a 2-Stage. The ports on the separator are also 4 inches. 
I am fine with 4 inch ductwork. There's not a huge price difference  between 4 and 5 inch pvc. I just want to know if there's any benefit or problem with running ductwork that's larger than the ports on the collector and separator.  Any advice or experience anyone can share with me would be greatly appreciated. And if anyone has anything to say about grounding the dust collection system,  and whether it's actually necessary for a hobbyist weekend warrior's shop, I'd love to hear your thoughts. 

Thanks,  and everyone have a great weekend.



Offline SRSemenza

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Re: Dust Collection System
« Reply #1 on: April 18, 2020, 10:46 AM »
There are people on the forum that know way more about this than I do, but I am betting that 4" duct will do very well.  I use 4".   My longest run is a 10' hose (4") into 20' of 4" duct that has two 90 degree bends. 

The thing is that there are a bunch of factors involved besides the diameter ......................  power cfm of the unit, length of runs, filter, cyclone, etc. Those all effect the flow.

Do you have any 4" (even a hose) that you can use to do a little of your own testing?  EX - if a 4" hose works well in a less than optimal set up then the 4" duct should work better with a better set up. Doing that might answer your question to your own satisfaction without needing to become a dust collection engineer and go through a lot of unnecessary factoring and decision making.

Seth

Offline Cheese

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Re: Dust Collection System
« Reply #2 on: April 18, 2020, 11:18 AM »
Just some general information.

As a rule of thumb, every 90º elbow added to the system is the equivalent of adding 10' of straight duct work.
Using 2 each 45º elbows with some space in between is better than a single 90º elbow.

The use of long radius elbows is always preferred.
https://www.oneida-air.com/ductwork/standard-ducting/long-radius-adjustable-dust-collection-elbows

You're talking about duct work which is metal and also talking about pvc pipe which is plastic, is this system a hybrid and you're using both?

Increasing the diameter to 5" will decrease the velocity, I'd just stick with the 4".
« Last Edit: April 19, 2020, 09:26 AM by Cheese »

Offline jeffinsgf

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Re: Dust Collection System
« Reply #3 on: April 18, 2020, 12:55 PM »
I was in favor of running the duct at 5-inch, until I read that the inlet to the dust collector was 4-inch. I don't think you want to run duct any larger than the inlet size. That is a (very) non-professional opinion...it just seems counter-intuitive to me.

Offline Alanbach

  • Posts: 587
Re: Dust Collection System
« Reply #4 on: April 18, 2020, 01:26 PM »
Two things. First, I have 5” duct run to my Sawstop (4” outlet on the saw) with a 5” reducer at the saw per the works great with my 2hp cyclone system. Doing that at the tool end as opposed to what your doing (at the DC end) might make a difference, I don’t know.

Second, can you remove the splitter that creates two 4” openings on your DC and see what’s underneath. It might be a larger opening???

Offline rst

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Re: Dust Collection System
« Reply #5 on: April 18, 2020, 02:03 PM »
Duct reduction should always be at the tool end.

Offline ryanjg117

  • Posts: 252
Re: Dust Collection System
« Reply #6 on: April 19, 2020, 03:12 AM »
Can you tell us more about your dust collector (make, model, horsepower)?

I ran 6" PVC along the ceilings of my shop, but my DC was designed for it. Only stepping down diameter at the tool end, and only when absolutely required. You'll usually end up with some amount of flex-hose near the tool as well, just to keep some flexibility for moving the tool around. It's wise to keep that flex hose to a minimum since it has much more internal resistance than the smooth walls of PVC pipe.

Note, the price on PVC S&D pipe goes up exponentially once you pass 4" I think.

Offline Cheese

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Re: Dust Collection System
« Reply #7 on: April 19, 2020, 10:52 AM »
You'll usually end up with some amount of flex-hose near the tool as well, just to keep some flexibility for moving the tool around. It's wise to keep that flex hose to a minimum since it has much more internal resistance than the smooth walls of PVC pipe.

As Ryan noted, you'll probably have to install some flex hose somewhere in the system. Use as little as possible because of its reduced CFM capabilities. Properly support it to prevent kinking and if possible "stretch" it to maintain the smoothest interior surface.

Here's some interesting reading, some things I agree with while some others I don't...however, it's still information.  [smile]
https://billpentz.com/woodworking/cyclone/ducting.cfm

For an elegant method to attach the duct hose to the tools, I prefer to use these. They simply couple together with magnets.
https://magport.net/collections/all




Offline Climber39

  • Posts: 55
Re: Dust Collection System
« Reply #8 on: April 20, 2020, 10:06 AM »
Just some general information.

As a rule of thumb, every 90º elbow added to the system is the equivalent of adding 10' of straight duct work.
Using 2 each 45º elbows with some space in between is better than a single 90º elbow.

The use of long radius elbows is always preferred.
https://www.oneida-air.com/ductwork/standard-ducting/long-radius-adjustable-dust-collection-elbows

You're talking about duct work which is metal and also talking about pvc pipe which is plastic, is this system a hybrid and you're using both?

Increasing the diameter to 5" will decrease the velocity, I'd just stick with the 4".

My apologies, I should've been more clear about the materials I'm considering.  I was using "ductwork" as a generic term, not to describe the material. I'll probably end up using PVC, as it appears to be more cost effective.

Offline Climber39

  • Posts: 55
Re: Dust Collection System
« Reply #9 on: April 20, 2020, 10:08 AM »
I was in favor of running the duct at 5-inch, until I read that the inlet to the dust collector was 4-inch. I don't think you want to run duct any larger than the inlet size. That is a (very) non-professional opinion...it just seems counter-intuitive to me.

That was my general feeling as well.  But I kept hearing that I should keep the duct as large and straight as possible. Thank you for responding.  You guys are a tremendous resource.

Offline Climber39

  • Posts: 55
Re: Dust Collection System
« Reply #10 on: April 20, 2020, 10:10 AM »
Two things. First, I have 5” duct run to my Sawstop (4” outlet on the saw) with a 5” reducer at the saw per the works great with my 2hp cyclone system. Doing that at the tool end as opposed to what your doing (at the DC end) might make a difference, I don’t know.

Second, can you remove the splitter that creates two 4” openings on your DC and see what’s underneath. It might be a larger opening???

That's a great idea,  I didn't think about removing the splitter. Definitely going to check that out tonight.

Offline jeffinsgf

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Re: Dust Collection System
« Reply #11 on: April 20, 2020, 10:12 AM »
I know the OP is looking to put together a central system, but I want to hijack the thread long enough to second Cheese's comment about Magport. I just put them on all the equipment in our model shop, and they're brilliant. If you're rolling one dust collector around to different machines, or swapping one central branch between two machines, I would highly recommend Magport.

Offline CeeJay

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Re: Dust Collection System
« Reply #12 on: April 21, 2020, 07:41 AM »
This is my system which I installed over Christmas:


 
It’s a 4” pvc system running off a 2hp DC. It’s 4” all the way from DC to machine for each of the 4 machines and each machine has a 4” port. Blast-gate at each machine. Copper wire run through each length, bare metal grounded at the DC and each machine.

For the table saw it’s about 20’ of duct, 2 blast gates, 3 x 45 deg bend and 3 x 90 deg bend. The suction is OK but could be better. For the jointer, thicknesser and bandsaw it’s fine. So maybe in 10 years or so I might upgrade to 6” duct. The intake on the DC is 6”, currently with a 4” reducer.

I was going to run a floor sweep as well but I just use the CT Midi now so this system will stay dedicated to the large machines with the CT for power tools.


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