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CFM for Dust collection Systems.....


comp56

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well I figured I would post some info about CFM's needed in a typical shop and some of the basic tools that go with a dust collection system.

there are many options out there from just a bag that your tool comes with some times right up to very expensive dust collection systems. The most common for a small DIYer shop would be a shop vac.

this can get complicated when it comes to the science of it all, unless you understand,

Shop vac are known for having low-volume air flow with high static pressure and most duct collector systems have high-volume air flow with low-volume pressure, what is the difference?

Air volume is measured in CFM's (cubic feet per minute) or liter per second (l/s) the volume of air that the device can move from its intake to its exhaust in a given amount of time.

Static pressure is measured in inches of water (also known as inches water column, or inches WC), the amount of inches the suction device can lift water up a pipe, or in millibar (mbar).

In simple terms, (“static pressure loss”) is how much your dust collector can overcome to move a given amount of air through it hose or pipe .

here is a rough estimate of CFM's needed for some common tools:

Table saw, radial arm saw, miter saw, bandsaw: 350 CFM, 165 l/s
Belt, disc, or drum sander: 350-550 CFM, 165-260 l/s (depending on size)
Table-mounted router: 195 CFM, 92 l/s
Thickness planer, up to 13": 400 CFM, 190 l/s
let's take a look at a ”6.5 peak horsepower” Shop-Vac vacuum rated at 9.3A@120V produces 185 CFM (87 l/s) of airflow and 64 inches (160 mbar) of pressure. you hook it up and is seems to be keeping things clean but technically it is falling short from the lowest on the list to actually do the proper job.

remember with any system the longer the hose the weaker it gets, though some corners and T's for second hoses and it get worse and worse.

a shop vac will drop way faster than a typical dust collection system but will as well just not as bad or as fast.

if anyone has better numbers and facts chime in we are helping each other and I'm just a hobbyist .....

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I do not have better numbers for you, but I have some experience with both shop vacs and larger units.  

 

I started off using a shop vac with their standard filter.  I would keep up with most of my tools like my table saw and hand sanders....at least the visible dust. But in all reality, the harmful dust was shooting by the shop vac filter.   Plus whenever the filter got plugged, the performance dropped....and fast.

 

I added a dust deputy to the system and that helped with the performance.  The filter in the shop vac almost never got plugged.

 

Then I added some bigger dust and chip producing tools...ie, jointer, thickness planer, and drum sander.  These tools produce a ton of wood waste and in the case of the drum sander, the manufacture required 600 cfm of air volume to keep up with the unit.  The dust produced from this tool is very fine and can lead to respiratory issues in the long run.  The shop vac couldn't do an adequate job for these tools.  Time to upgrade.

 

I purchased a 2 HP jet DC unit and piped up my entire shop with sewer pipe and blast gates.  This unit has so much air flow that it easily handles all that I need.  It also have a 1 micron filter that takes care of a good amount of the harmful dust.  

 

I know if you are looking at upgrading to a large shop unit, Oneida air systems and ClearVue will both help you calculate your runs and size the system accordingly.

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I am at the stage where I have a shop vac and dust deputy, sure it keeps the filter clean but same thing it is useless with my planer and sander. it is better than nothing but time to upgrade........

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7 hours ago, comp56 said:

I am at the stage where I have a shop vac and dust deputy, sure it keeps the filter clean but same thing it is useless with my planer and sander. it is better than nothing but time to upgrade........

I have the same setup, works fine for me right now, but if I wish to do more "hardcore" things I will need an upgrade.

does anyone have any type of sound level reference ? My shop is small, half of a 2 car garage and noise levels do matter some what, especially in the placement of the unit.

Thanks @comp56 for all of the above info !!!

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8 hours ago, tugnut1 said:

I do not have better numbers for you, but I have some experience with both shop vacs and larger units.  

 

I started off using a shop vac with their standard filter.  I would keep up with most of my tools like my table saw and hand sanders....at least the visible dust. But in all reality, the harmful dust was shooting by the shop vac filter.   Plus whenever the filter got plugged, the performance dropped....and fast.

 

I added a dust deputy to the system and that helped with the performance.  The filter in the shop vac almost never got plugged.

 

Then I added some bigger dust and chip producing tools...ie, jointer, thickness planer, and drum sander.  These tools produce a ton of wood waste and in the case of the drum sander, the manufacture required 600 cfm of air volume to keep up with the unit.  The dust produced from this tool is very fine and can lead to respiratory issues in the long run.  The shop vac couldn't do an adequate job for these tools.  Time to upgrade.

 

I purchased a 2 HP jet DC unit and piped up my entire shop with sewer pipe and blast gates.  This unit has so much air flow that it easily handles all that I need.  It also have a 1 micron filter that takes care of a good amount of the harmful dust.  

 

I know if you are looking at upgrading to a large shop unit, Oneida air systems and ClearVue will both help you calculate your runs and size the system accordingly.

I finally went with a dedicated 1.5hp unit....

http://www.supermaxtools.com/products/dust-collection/1-12-hp-dust-collector/

alongside a Grizzly three speed air cleaner. I haven't finished the shop yet and the Supermax remains boxed but I've had the Grizzly a couple of years and it's great. I just got some new filters for it. Also use the Festool MIDI with HEPA on all of my Festools and my Bosch sander. All in all this will make my shop a whole lot cleaner.

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54 minutes ago, Foneguy said:

I have the same setup, works fine for me right now, but if I wish to do more "hardcore" things I will need an upgrade.

does anyone have any type of sound level reference ? My shop is small, half of a 2 car garage and noise levels do matter some what, especially in the placement of the unit.

Thanks @comp56 for all of the above info !!!

The Supermax is rated at 78db Buddy!

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15 hours ago, Foneguy said:

I have the same setup, works fine for me right now, but if I wish to do more "hardcore" things I will need an upgrade.

does anyone have any type of sound level reference ? My shop is small, half of a 2 car garage and noise levels do matter some what, especially in the placement of the unit.

Thanks @comp56 for all of the above info !!!

 

The Jet 2hp cyclone unit is pretty quiet.  It was listed in the 75-ish dB when I was looking into it.  This was one of the most important stats for me.  That being said, I think it is louder than 75 dB, but it is most certainly under the 85 dB that requires hearing protection and much more quiet than a shop vac.

 

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  • 3 weeks later...

Anyone got their dust collection outside the shop area? Maybe in the case of a garage shop just outside the exterior wall in a simple weather resistant framed in enclosure? or maybe a room connected to the shop? Would it be worth it to be in a different room? Less noise and space savings?

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17 minutes ago, Jronman said:

Anyone got their dust collection outside the shop area? Maybe in the case of a garage shop just outside the exterior wall in a simple weather resistant framed in enclosure? or maybe a room connected to the shop? Would it be worth it to be in a different room? Less noise and space savings?

 

I've seen setups where the vac is in a different room, or on a different level.  I've also seen them where they are in the shop, but someone builds walls around it to keep the noise down.  I know a lot of the older vacs are very very loud, but the newer ones seem to work at much more tolerable decibel levels.

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9 minutes ago, tugnut1 said:

 

I've seen setups where the vac is in a different room, or on a different level.  I've also seen them where they are in the shop, but someone builds walls around it to keep the noise down.  I know a lot of the older vacs are very very loud, but the newer ones seem to work at much more tolerable decibel levels.

I see a lot of setups where the vac is tucked into a corner and would not be very accessible. Maybe placing a unit outside with proper weather protection would be more accessible?

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