Once again I'm fitting another device for dust collection. And once
again I'm irritated by the fact that nothing fits without an adaptor.
Seems to me all that should be needed is:
4" male connection
4" female connection
2.5" male connection
2.5" female connection
All hoses should come with female on one end and male on the other.
All dust collection devices should accept a male connector.
All dust producing devices should accept a female connector.
Add the following adapters:
2.5" male to 4" male adapter
2.5" male to 4" female adapter
2.5" female to 4" male adapter
2.5" female to 4" female adapter
4 more adapters, but elbows instead of straight.
Wouldn't that make life a lot simpler?
Maybe I'll send this post to a couple of the woodworking magazines :-).
--
When fascism comes to America, it will be wrapped in the flag and
carrying a cross.
On Tue, 01 Mar 2016 21:12:27 -0600, dpb <[email protected]> wrote:
>On 03/01/2016 7:26 PM, krw wrote:
>...
>
>> Doesn't the length matter, also? A larger diameter will have less
>> friction losses. Of course this all assumes a large enough DC to keep
>> the air moving in the pipe.
>
>It will, but unless the lengths are quite long which is unlikely in most
>home/small one-man shops, friction loss difference owing to pipe
>diameter is likely not a big effect.
I may have to go a bit further than I'd like to get to all the tools.
I may just service a few of them with the DC, though, and use shop
vacs elsewhere.
>
>_BUT_, for those same shops, the cfm to keep the same linear velocity
>has to go up by >150% which really begins to strain the size of most
>DC's folks are going to have at that size shop or want to invest the $$
>for...
The port on my DC is 6" (with a 2x 4" adapter), so my thought was to
just extend this as the main line(s) and split off that to 4". 6"
stuff is a PITA to work with so if 4" works, I'm all for it.
Right now I just have 4" flex hose on the floor and connect the tool
I'm using but I want to clean that up so it's not a pain to use the
tools.
On 3/1/2016 2:55 PM, Unquestionably Confused wrote:
> On 3/1/2016 1:53 PM, Larry Kraus wrote:
>> My gripe (besides the lack of standards) is that all the research I can
>> find says that 4" pipe is too small for more than a single machine, but
>> that is the most common size available. Collection for small home shop
>> garage with 3-4 machines seems to need a system based on 5" pipe.
>> Finding fittings that work properly with that are very difficult to find.
>
> While I've always heard that 5" or 6" pipe is better than 4" for dust
> collection.
>
> Your qualifier (> 1 machine) raises a good point. How many of us run
> several dusty machines simultaneously? It would be great if I could get
> SWMBO out in the shop to surface plane some wood while I cut some sheet
> goods down to size, but that ain't gonna happen<g>
>
> So... 4" seems like it will fit the bill just fine when combined with a
> good enough dust collector.
99.99% of the time a single man shop is only going to use one machine at
a time. 4" is plenty.
On Sun, 28 Feb 2016 16:47:56 -0600, dpb <[email protected]> wrote:
>On 02/28/2016 4:10 PM, krw wrote:
>...
>
>>> Then you'd have the same problem when using (better if more expensive)
>>> metal ducting.
>>
>> How is it better than PVC?
>
>Lower friction, no static buildup...
Do you have a reference for friction? Not doubting you but I'd like
to understand how big an issue it is. I've never worried much about
static (in the woodworking context).
On 3/1/2016 1:53 PM, Larry Kraus wrote:
> My gripe (besides the lack of standards) is that all the research I can
> find says that 4" pipe is too small for more than a single machine, but
> that is the most common size available. Collection for small home shop
> garage with 3-4 machines seems to need a system based on 5" pipe.
> Finding fittings that work properly with that are very difficult to find.
While I've always heard that 5" or 6" pipe is better than 4" for dust
collection.
Your qualifier (> 1 machine) raises a good point. How many of us run
several dusty machines simultaneously? It would be great if I could get
SWMBO out in the shop to surface plane some wood while I cut some sheet
goods down to size, but that ain't gonna happen<g>
So... 4" seems like it will fit the bill just fine when combined with a
good enough dust collector.
On Sun, 28 Feb 2016 08:24:21 -0600, dpb <[email protected]> wrote:
>On 02/27/2016 9:30 PM, krw wrote:
>> On Sun, 28 Feb 2016 01:10:50 +0000 (UTC), Larry Blanchard
>> <[email protected]> wrote:
>>> Once again I'm fitting another device for dust collection. And once
>>> again I'm irritated by the fact that nothing fits without an adaptor.
>...
>
>> I'd be really happy if all 4" male pieces even fit 4" female pieces.
>> I'd give big bonus points if they'd fit 4" PVC pieces.
>
>Then you'd have the same problem when using (better if more expensive)
>metal ducting.
How is it better than PVC?
On Mon, 29 Feb 2016 17:37:16 -0600, dpb <[email protected]> wrote:
>On 02/28/2016 7:17 PM, krw wrote:
>> On Sun, 28 Feb 2016 16:47:56 -0600, dpb<[email protected]> wrote:
>>
>>> On 02/28/2016 4:10 PM, krw wrote:
>>> ...
>>>
>>>>> Then you'd have the same problem when using (better if more expensive)
>>>>> metal ducting.
>>>>
>>>> How is it better than PVC?
>>>
>>> Lower friction, no static buildup...
>>
>> Do you have a reference for friction? Not doubting you but I'd like
>> to understand how big an issue it is. I've never worried much about
>> static (in the woodworking context).
>
>Hadn't seen the reply, sorry...
No problem. It's not like it's an emergency. ;-)
>
>Not huge altho my experience has been that the static buildup tends to
>cause small stuff to stick to the surface which can't help.
I was wondering more about the airflow resistance increase, though I
can see where dust sticking to joints wouldn't help. Is there a
significant air resistance difference between "clean" metal and
"clean" PVC?
>
>The static buildup in small shop settings at least is mostly just a
>nuisance factor that I dislike simply for the effect. It is virtually
>impossible to ignite a wood dust cloud with it as the ignition source;
>while pretty high voltage and zap when you're the target, it has very
>low actual energy. After the other thread I did a little looking but
>wasn't able to find in a short period the paper I'd seen a number of
>years ago where a guy at T A&M did some discharge measurements,
>unfortunately.
Yeah, though others may disagree, I think this horse has been beaten
near enough to death.
On Saturday, February 27, 2016 at 7:11:01 PM UTC-6, Larry Blanchard wrote:
> Once again I'm fitting another device for dust collection. And once
> again I'm irritated by the fact that nothing fits without an adaptor.
> Seems to me all that should be needed is:
>
> 4" male connection
> 4" female connection
> 2.5" male connection
> 2.5" female connection
>
> All hoses should come with female on one end and male on the other.
>
> All dust collection devices should accept a male connector.
>
> All dust producing devices should accept a female connector.
>
> Add the following adapters:
>
> 2.5" male to 4" male adapter
> 2.5" male to 4" female adapter
> 2.5" female to 4" male adapter
> 2.5" female to 4" female adapter
> 4 more adapters, but elbows instead of straight.
>
> Wouldn't that make life a lot simpler?
>
> Maybe I'll send this post to a couple of the woodworking magazines :-).
>
>
> --
> When fascism comes to America, it will be wrapped in the flag and
> carrying a cross.
It would, but where would the challenge be? ;-)
Seriously, you are absolutely correct, there should be a standard for all dust fittings.
Deb
My gripe (besides the lack of standards) is that all the research I can
find says that 4" pipe is too small for more than a single machine, but
that is the most common size available. Collection for small home shop
garage with 3-4 machines seems to need a system based on 5" pipe.
Finding fittings that work properly with that are very difficult to find.
On Sun, 28 Feb 2016 01:10:50 +0000 (UTC), Larry Blanchard
<[email protected]> wrote:
>
>Once again I'm fitting another device for dust collection. And once
>again I'm irritated by the fact that nothing fits without an adaptor.
>Seems to me all that should be needed is:
>
>4" male connection
>4" female connection
>2.5" male connection
>2.5" female connection
>
>All hoses should come with female on one end and male on the other.
>
>All dust collection devices should accept a male connector.
>
>All dust producing devices should accept a female connector.
>
>Add the following adapters:
>
>2.5" male to 4" male adapter
>2.5" male to 4" female adapter
>2.5" female to 4" male adapter
>2.5" female to 4" female adapter
>4 more adapters, but elbows instead of straight.
>
>Wouldn't that make life a lot simpler?
>
>Maybe I'll send this post to a couple of the woodworking magazines :-).
I'd be really happy if all 4" male pieces even fit 4" female pieces.
I'd give big bonus points if they'd fit 4" PVC pieces.
On Tuesday, March 1, 2016 at 3:52:16 PM UTC-6, Leon wrote:
=20
> 99.99% of the time a single man shop is only going to use one machine at=
=20
> a time. 4" is plenty.
AGree. =20
I have found that to be true even when I am working in an occupied house as=
well to manage the dust problem. I hook up the machine to my sanders, have=
a helper hold the hose for my sawzalll and oscillator tool cuts, and let t=
he machine run all day in the work area with enough hose to get the actual =
machine/bag outside or in the garage. Putting the machine outside of the l=
iving area I can use a 3 mil bag for good air flow. My machine gets too ho=
t after a couple of hours with the 1 mil bag on it, and since the collector=
will pull all the dust it needs to by sheer volume of air moved, 4" works =
fine.
Robert
On Tuesday, March 1, 2016 at 9:57:25 PM UTC-6, Leon wrote:
=20
> I think the only time length is going to matter is if you have a bunch=20
> of leaking blast gates and or leaking fittings. I have none.
Nor do I. And when I use mine it never has to make a vertical lift. It ro=
lls around on wheels and is about 12" off the ground when in use, just high=
enough to let the bag inflate and then droop a bit when getting close to f=
ull. I probably about about 25 - 30 ft on the collector, down from the len=
gth of the hose I purchased originally at 50'. =20
When it was still 50', I didn't have any problems with it in the slightest.
Robert
On Wed, 02 Mar 2016 20:53:52 -0600, dpb <[email protected]> wrote:
>On 03/02/2016 7:52 PM, OFWW wrote:
>> On Wed, 02 Mar 2016 12:56:18 -0600, dpb<[email protected]> wrote:
>>
>>> On 02/29/2016 7:25 PM, krw wrote:
>>> ...
>>>
>>>> I was wondering more about the airflow resistance increase, though I
>>>> can see where dust sticking to joints wouldn't help. Is there a
>>>> significant air resistance difference between "clean" metal and
>>>> "clean" PVC?
>>>
>>> For straight pipe, no. Where I was headed was that the fittings (el's,
>>> wye's, etc.) associated with PVC are much tighter radius (even "long"
>>> el's) than those used in "proper" dust collection and handling systems
>>> and a single elbow is some 5X the dP of 100 ft of straight pipe whereas
>>> for the metal ducting with 1.5 radius it's more like 1.5-2.0X. That
>>> differential will more than make up for whatever minor improvement the
>>> straight PVC might have over the galvanized.
>>>
>>> I've got quite a bit of data and design stuff from various sources but
>>> haven't ever actually put it all together as a easy-to-use pattern w/o
>>> being intimate w/ the details of what the various pieces mean -- stuff
>>> like which friction-factor formulation goes with which pressure drop
>>> correlation, etc., etc., ...
>>>
>>> Since I'm in the process of setting up a new area in the barn and will
>>> have to do at least a modicum of this shortly, maybe this will be the
>>> impetus to try to consolidate some of that to a more "handbooky" kind of
>>> process...
>>>
>>> The upshot is, however, that you need to keep the sizes such that for
>>> whatever CFM you have the linear velocity for branch lines of roughly
>>> 4000 fpm and 3500 fpm or so for main ducts. This will ensure won't have
>>> issues w/ drop out and so on. If the chip sizes are small or dust like
>>> a sander, you can get by w/ somewhat less; the above are targets for
>>> that include planers, shapers, routers, etc., that make a fair-sized chip.
>>>
>>> Just for info, though, the difference in cfm required for 3500 fpm is
>>>
>>> 3" 170
>>> 4" 300
>>> 5" 475
>>> 6" 600
>>>
>>> As you note, it goes up by the ratio of cross-section areas, obviously.
>>> The fortunate thing is, of course that the percentage increase in area
>>> decreases from step to step in uniform diameter increments so the
>>> biggest jump is from 3" to 4"; 4" to 5" isn't quite as painful.
>>>
>>> Hopefully that helps..
>>
>> This link might save you some time and trouble.
>> http://hhrwoodworkingclub.org/Dust%20Collection%20System%20Design%2010%20April%2009.pdf
>>
>> One thing you did not mention was the inches of water column necessary
>> for the flow. This will help you with the sizing of the DC needed, or
>> if done in reverse what you can due with what you have.
>
>Just didn't seem pertinent to the question asked...
>
>Static Head ("in H20) for given diameter at linear flow velocity...
>
>Diam 3500 4500
>3? 7.5 10.0
>4? 5.5 7.0
>5? 4.2 5.5
>6? 3.5 4.5
>7? 2.8 3.8
>8? 2.4 3.2
To me it does, for how else can you determine the flow in a given size
of pipe? If the DC is undersized then the negative static pressure
will be less as will the CFM and FPM. I was hoping that the pdf I
linked to would help you both. It also confirmed some of what you were
saying.
On Tue, 1 Mar 2016 14:55:26 -0600, Unquestionably Confused
<[email protected]> wrote:
>On 3/1/2016 1:53 PM, Larry Kraus wrote:
>> My gripe (besides the lack of standards) is that all the research I can
>> find says that 4" pipe is too small for more than a single machine, but
>> that is the most common size available. Collection for small home shop
>> garage with 3-4 machines seems to need a system based on 5" pipe.
>> Finding fittings that work properly with that are very difficult to find.
>
>While I've always heard that 5" or 6" pipe is better than 4" for dust
>collection.
>
>Your qualifier (> 1 machine) raises a good point. How many of us run
>several dusty machines simultaneously? It would be great if I could get
>SWMBO out in the shop to surface plane some wood while I cut some sheet
>goods down to size, but that ain't gonna happen<g>
>
>So... 4" seems like it will fit the bill just fine when combined with a
>good enough dust collector.
Doesn't the length matter, also? A larger diameter will have less
friction losses. Of course this all assumes a large enough DC to keep
the air moving in the pipe.
On 3/1/2016 7:26 PM, krw wrote:
> On Tue, 1 Mar 2016 14:55:26 -0600, Unquestionably Confused
> <[email protected]> wrote:
>
>> On 3/1/2016 1:53 PM, Larry Kraus wrote:
>>> My gripe (besides the lack of standards) is that all the research I can
>>> find says that 4" pipe is too small for more than a single machine, but
>>> that is the most common size available. Collection for small home shop
>>> garage with 3-4 machines seems to need a system based on 5" pipe.
>>> Finding fittings that work properly with that are very difficult to find.
>>
>> While I've always heard that 5" or 6" pipe is better than 4" for dust
>> collection.
>>
>> Your qualifier (> 1 machine) raises a good point. How many of us run
>> several dusty machines simultaneously? It would be great if I could get
>> SWMBO out in the shop to surface plane some wood while I cut some sheet
>> goods down to size, but that ain't gonna happen<g>
>>
>> So... 4" seems like it will fit the bill just fine when combined with a
>> good enough dust collector.
>
> Doesn't the length matter, also? A larger diameter will have less
> friction losses. Of course this all assumes a large enough DC to keep
> the air moving in the pipe.
>
Length in a home shop may not be an issue. I use the clear wire
reinforced flex hose, the robust kind, not the flimsy kind.
Anyway it is any thing but smooth inside and is 30' long. It leaves the
DC, goes straight up to about 7' high, over 8', and back down to the
floor, and lots of loops bends and curves, to what ever I choose to hook
it up to. No loss of suction at all. This is with an 1100 CFM DC with
the pleated top filter.
I have 3, 10' lengths coupled together.
http://www.rockler.com/clear-flexible-dust-collection-hose-optional-sizes
I think the only time length is going to matter is if you have a bunch
of leaking blast gates and or leaking fittings. I have none.
On Mon, 29 Feb 2016 17:28:58 -0600, dpb <[email protected]> wrote:
>On 02/29/2016 4:44 PM, Dr. Deb wrote:
>...
>
>> Seriously, you are absolutely correct, there should be a standard
>> for all dust fittings.
>
>Is...biggest problem is folks are using non-dust-collection stuff for
>the purpose (PVC, primarily).
That's one problem (why can't dust collection stuff use one of the
other standards anyway) but DC stuff doesn't even fit DC stuff. Not
even close.
On Wed, 02 Mar 2016 12:56:18 -0600, dpb <[email protected]> wrote:
>On 02/29/2016 7:25 PM, krw wrote:
>...
>
>> I was wondering more about the airflow resistance increase, though I
>> can see where dust sticking to joints wouldn't help. Is there a
>> significant air resistance difference between "clean" metal and
>> "clean" PVC?
>
>For straight pipe, no. Where I was headed was that the fittings (el's,
>wye's, etc.) associated with PVC are much tighter radius (even "long"
>el's) than those used in "proper" dust collection and handling systems
>and a single elbow is some 5X the dP of 100 ft of straight pipe whereas
>for the metal ducting with 1.5 radius it's more like 1.5-2.0X. That
>differential will more than make up for whatever minor improvement the
>straight PVC might have over the galvanized.
>
>I've got quite a bit of data and design stuff from various sources but
>haven't ever actually put it all together as a easy-to-use pattern w/o
>being intimate w/ the details of what the various pieces mean -- stuff
>like which friction-factor formulation goes with which pressure drop
>correlation, etc., etc., ...
>
>Since I'm in the process of setting up a new area in the barn and will
>have to do at least a modicum of this shortly, maybe this will be the
>impetus to try to consolidate some of that to a more "handbooky" kind of
>process...
>
>The upshot is, however, that you need to keep the sizes such that for
>whatever CFM you have the linear velocity for branch lines of roughly
>4000 fpm and 3500 fpm or so for main ducts. This will ensure won't have
>issues w/ drop out and so on. If the chip sizes are small or dust like
>a sander, you can get by w/ somewhat less; the above are targets for
>that include planers, shapers, routers, etc., that make a fair-sized chip.
>
>Just for info, though, the difference in cfm required for 3500 fpm is
>
>3" 170
>4" 300
>5" 475
>6" 600
>
>As you note, it goes up by the ratio of cross-section areas, obviously.
> The fortunate thing is, of course that the percentage increase in area
>decreases from step to step in uniform diameter increments so the
>biggest jump is from 3" to 4"; 4" to 5" isn't quite as painful.
>
>Hopefully that helps..
This link might save you some time and trouble.
http://hhrwoodworkingclub.org/Dust%20Collection%20System%20Design%2010%20April%2009.pdf
One thing you did not mention was the inches of water column necessary
for the flow. This will help you with the sizing of the DC needed, or
if done in reverse what you can due with what you have.
On Sat, 05 Mar 2016 13:21:40 -0800, OFWW <[email protected]> wrote:
>On Sat, 05 Mar 2016 09:54:45 -0500, krw <[email protected]> wrote:
>
>>On Wed, 02 Mar 2016 12:56:18 -0600, dpb <[email protected]> wrote:
>>
>>>On 02/29/2016 7:25 PM, krw wrote:
>>>...
>>>
>>>> I was wondering more about the airflow resistance increase, though I
>>>> can see where dust sticking to joints wouldn't help. Is there a
>>>> significant air resistance difference between "clean" metal and
>>>> "clean" PVC?
>>>
>>>For straight pipe, no. Where I was headed was that the fittings (el's,
>>>wye's, etc.) associated with PVC are much tighter radius (even "long"
>>>el's) than those used in "proper" dust collection and handling systems
>>>and a single elbow is some 5X the dP of 100 ft of straight pipe whereas
>>>for the metal ducting with 1.5 radius it's more like 1.5-2.0X. That
>>>differential will more than make up for whatever minor improvement the
>>>straight PVC might have over the galvanized.
>>>
>>>I've got quite a bit of data and design stuff from various sources but
>>>haven't ever actually put it all together as a easy-to-use pattern w/o
>>>being intimate w/ the details of what the various pieces mean -- stuff
>>>like which friction-factor formulation goes with which pressure drop
>>>correlation, etc., etc., ...
>>>
>>>Since I'm in the process of setting up a new area in the barn and will
>>>have to do at least a modicum of this shortly, maybe this will be the
>>>impetus to try to consolidate some of that to a more "handbooky" kind of
>>>process...
>>>
>>>The upshot is, however, that you need to keep the sizes such that for
>>>whatever CFM you have the linear velocity for branch lines of roughly
>>>4000 fpm and 3500 fpm or so for main ducts. This will ensure won't have
>>>issues w/ drop out and so on. If the chip sizes are small or dust like
>>>a sander, you can get by w/ somewhat less; the above are targets for
>>>that include planers, shapers, routers, etc., that make a fair-sized chip.
>>>
>>>Just for info, though, the difference in cfm required for 3500 fpm is
>>>
>>>3" 170
>>>4" 300
>>>5" 475
>>>6" 600
>>>
>>>As you note, it goes up by the ratio of cross-section areas, obviously.
>>> The fortunate thing is, of course that the percentage increase in area
>>>decreases from step to step in uniform diameter increments so the
>>>biggest jump is from 3" to 4"; 4" to 5" isn't quite as painful.
>>>
>>>Hopefully that helps..
>>
>>That helps a lot. Thanks guys. I'll have to digest this some more.
>>Maybe I don't have the problem I thought I did and can use a longer
>>run (with blast gates). Do you happen to know of an easy way to
>>measure the flow rate?
>
>You can make a U-Tube Manometer. It is the cheapest way I know of,
>otherwise you can buy one, at an HVAC supply house or WW Graingers.
>
>Measure the inches of water negative pressure, take the inside
>diameter of the pipe you measured and compare it to a FPM chart on one
>of the links I provided. It will require that you drill a hole to
>connect the U-tube to, with no leakage while connected. I can find you
>a how to on it if desired.
Sure, I'd appreciate any help here (thank you, again). I probably
won't get to the DC system for some time so there is no rush.
On 02/27/2016 9:30 PM, krw wrote:
> On Sun, 28 Feb 2016 01:10:50 +0000 (UTC), Larry Blanchard
> <[email protected]> wrote:
>> Once again I'm fitting another device for dust collection. And once
>> again I'm irritated by the fact that nothing fits without an adaptor.
...
> I'd be really happy if all 4" male pieces even fit 4" female pieces.
> I'd give big bonus points if they'd fit 4" PVC pieces.
Then you'd have the same problem when using (better if more expensive)
metal ducting.
--
On 02/28/2016 7:17 PM, krw wrote:
> On Sun, 28 Feb 2016 16:47:56 -0600, dpb<[email protected]> wrote:
>
>> On 02/28/2016 4:10 PM, krw wrote:
>> ...
>>
>>>> Then you'd have the same problem when using (better if more expensive)
>>>> metal ducting.
>>>
>>> How is it better than PVC?
>>
>> Lower friction, no static buildup...
>
> Do you have a reference for friction? Not doubting you but I'd like
> to understand how big an issue it is. I've never worried much about
> static (in the woodworking context).
Hadn't seen the reply, sorry...
Not huge altho my experience has been that the static buildup tends to
cause small stuff to stick to the surface which can't help.
The static buildup in small shop settings at least is mostly just a
nuisance factor that I dislike simply for the effect. It is virtually
impossible to ignite a wood dust cloud with it as the ignition source;
while pretty high voltage and zap when you're the target, it has very
low actual energy. After the other thread I did a little looking but
wasn't able to find in a short period the paper I'd seen a number of
years ago where a guy at T A&M did some discharge measurements,
unfortunately.
--
On Sun, 28 Feb 2016 01:10:50 +0000 (UTC)
Larry Blanchard <[email protected]> wrote:
> All hoses should come with female on one end and male on the other.
they are trying to be gender neutral
it is a fad now
On Mon, 29 Feb 2016 17:28:58 -0600, dpb wrote:
> Is...biggest problem is folks are using non-dust-collection stuff for
> the purpose (PVC, primarily).
You obviously haven't looked through the racks of adapters at Rockler,
Woodcraft, et al. Most have nothing to do with PCV and the like.
For example, what prompted this gripe was one of those little cyclones
that fit on a 5 gallon bucket. They are designed to use with a shop
vacuum and therefore 2.5" connectors for both in and out. But they're
the exact same size as the fitting on the end of my vac hose, so I have
to get either an inside or outside coupler to hook the two together.
I used to work part time at Woodcraft. Time and time again a customer
would bring in a connector/adapter/coupler because it wouldn't fit his
new machine "but it fit my old one".
--
When fascism comes to America, it will be wrapped in the flag and
carrying a cross.
On 03/01/2016 1:53 PM, Larry Kraus wrote:
> My gripe (besides the lack of standards) is that all the research I can
> find says that 4" pipe is too small for more than a single machine, but
> that is the most common size available. Collection for small home shop
> garage with 3-4 machines seems to need a system based on 5" pipe.
> Finding fittings that work properly with that are very difficult to find.
Outside the box stores, yeah, but it's there...
<http://www.airhand.com/product-category/woodworking-hobby-shop-light-gauge-solution-for-spiral-pipe-fittings-and-hose/>
<http://www.kencraftcompany.com/Dustindex.htm>
<http://www.oneida-air.com/category.asp?Id={131D0222-43E5-48DC-987D-4031AA38B00C}>
There are others as well but as noted, prices become pretty dear pretty
quickly when you get out of the smaller hobby stuff. But, one could go
to simply a main 5" trunk line system which is where I'm headed
eventually when (finally!!! after "only" 15 yr or so) get the barn setup
operational. I've got the old blower from the silo unloader I'm
repurposing as the fan and an old cyclone separator from the feed
mill/grinder that helps some on components albeit with more time/effort
on fitting and construction...
--
On 03/01/2016 2:55 PM, Unquestionably Confused wrote:
...
> Your qualifier (> 1 machine) raises a good point. How many of us run
> several dusty machines simultaneously? It would be great if I could get
> SWMBO out in the shop to surface plane some wood while I cut some sheet
> goods down to size, but that ain't gonna happen<g>
>
> So... 4" seems like it will fit the bill just fine when combined with a
> good enough dust collector.
+1 as far as application...sizing is only limited by total
_simultaneous_ capacity.
And, of course, if one steps up in duct size, have to have the
commensurate air handler to keep adequate velocity and pressure drop as
well.
I only addressed the actual concern of availability earlier...
--
On 03/01/2016 7:26 PM, krw wrote:
...
> Doesn't the length matter, also? A larger diameter will have less
> friction losses. Of course this all assumes a large enough DC to keep
> the air moving in the pipe.
It will, but unless the lengths are quite long which is unlikely in most
home/small one-man shops, friction loss difference owing to pipe
diameter is likely not a big effect.
_BUT_, for those same shops, the cfm to keep the same linear velocity
has to go up by >150% which really begins to strain the size of most
DC's folks are going to have at that size shop or want to invest the $$
for...
--
On 02/29/2016 7:25 PM, krw wrote:
...
> I was wondering more about the airflow resistance increase, though I
> can see where dust sticking to joints wouldn't help. Is there a
> significant air resistance difference between "clean" metal and
> "clean" PVC?
For straight pipe, no. Where I was headed was that the fittings (el's,
wye's, etc.) associated with PVC are much tighter radius (even "long"
el's) than those used in "proper" dust collection and handling systems
and a single elbow is some 5X the dP of 100 ft of straight pipe whereas
for the metal ducting with 1.5 radius it's more like 1.5-2.0X. That
differential will more than make up for whatever minor improvement the
straight PVC might have over the galvanized.
I've got quite a bit of data and design stuff from various sources but
haven't ever actually put it all together as a easy-to-use pattern w/o
being intimate w/ the details of what the various pieces mean -- stuff
like which friction-factor formulation goes with which pressure drop
correlation, etc., etc., ...
Since I'm in the process of setting up a new area in the barn and will
have to do at least a modicum of this shortly, maybe this will be the
impetus to try to consolidate some of that to a more "handbooky" kind of
process...
The upshot is, however, that you need to keep the sizes such that for
whatever CFM you have the linear velocity for branch lines of roughly
4000 fpm and 3500 fpm or so for main ducts. This will ensure won't have
issues w/ drop out and so on. If the chip sizes are small or dust like
a sander, you can get by w/ somewhat less; the above are targets for
that include planers, shapers, routers, etc., that make a fair-sized chip.
Just for info, though, the difference in cfm required for 3500 fpm is
3" 170
4" 300
5" 475
6" 600
As you note, it goes up by the ratio of cross-section areas, obviously.
The fortunate thing is, of course that the percentage increase in area
decreases from step to step in uniform diameter increments so the
biggest jump is from 3" to 4"; 4" to 5" isn't quite as painful.
Hopefully that helps..
--
On 03/02/2016 7:52 PM, OFWW wrote:
> On Wed, 02 Mar 2016 12:56:18 -0600, dpb<[email protected]> wrote:
>
>> On 02/29/2016 7:25 PM, krw wrote:
>> ...
>>
>>> I was wondering more about the airflow resistance increase, though I
>>> can see where dust sticking to joints wouldn't help. Is there a
>>> significant air resistance difference between "clean" metal and
>>> "clean" PVC?
>>
>> For straight pipe, no. Where I was headed was that the fittings (el's,
>> wye's, etc.) associated with PVC are much tighter radius (even "long"
>> el's) than those used in "proper" dust collection and handling systems
>> and a single elbow is some 5X the dP of 100 ft of straight pipe whereas
>> for the metal ducting with 1.5 radius it's more like 1.5-2.0X. That
>> differential will more than make up for whatever minor improvement the
>> straight PVC might have over the galvanized.
>>
>> I've got quite a bit of data and design stuff from various sources but
>> haven't ever actually put it all together as a easy-to-use pattern w/o
>> being intimate w/ the details of what the various pieces mean -- stuff
>> like which friction-factor formulation goes with which pressure drop
>> correlation, etc., etc., ...
>>
>> Since I'm in the process of setting up a new area in the barn and will
>> have to do at least a modicum of this shortly, maybe this will be the
>> impetus to try to consolidate some of that to a more "handbooky" kind of
>> process...
>>
>> The upshot is, however, that you need to keep the sizes such that for
>> whatever CFM you have the linear velocity for branch lines of roughly
>> 4000 fpm and 3500 fpm or so for main ducts. This will ensure won't have
>> issues w/ drop out and so on. If the chip sizes are small or dust like
>> a sander, you can get by w/ somewhat less; the above are targets for
>> that include planers, shapers, routers, etc., that make a fair-sized chip.
>>
>> Just for info, though, the difference in cfm required for 3500 fpm is
>>
>> 3" 170
>> 4" 300
>> 5" 475
>> 6" 600
>>
>> As you note, it goes up by the ratio of cross-section areas, obviously.
>> The fortunate thing is, of course that the percentage increase in area
>> decreases from step to step in uniform diameter increments so the
>> biggest jump is from 3" to 4"; 4" to 5" isn't quite as painful.
>>
>> Hopefully that helps..
>
> This link might save you some time and trouble.
> http://hhrwoodworkingclub.org/Dust%20Collection%20System%20Design%2010%20April%2009.pdf
>
> One thing you did not mention was the inches of water column necessary
> for the flow. This will help you with the sizing of the DC needed, or
> if done in reverse what you can due with what you have.
Just didn't seem pertinent to the question asked...
Static Head ("in H20) for given diameter at linear flow velocity...
Diam 3500 4500
3â³ 7.5 10.0
4â³ 5.5 7.0
5â³ 4.2 5.5
6â³ 3.5 4.5
7â³ 2.8 3.8
8â³ 2.4 3.2
--
On 03/02/2016 10:15 PM, OFWW wrote:
...
> To me it does, for how else can you determine the flow in a given size
> of pipe? If the DC is undersized then the negative static pressure
> will be less as will the CFM and FPM. ...
Of course, but KRW wasn't trying to do a size computation per se, wo was
simply pointing out that he does, for the DC he has, need to look at
what the effect of his thought of using a given size of ductwork would
do to the resulting linear velocity. Have insufficient data available
to do anything more.
--
On 03/03/2016 12:14 AM, dpb wrote:
> On 03/02/2016 10:15 PM, OFWW wrote:
> ...
>
>> To me it does, for how else can you determine the flow in a given size
>> of pipe? If the DC is undersized then the negative static pressure
>> will be less as will the CFM and FPM. ...
>
> Of course, but KRW wasn't trying to do a size computation per se, wo was
> simply pointing out that he does, for the DC he has, need to look at
> what the effect of his thought of using a given size of ductwork would
> do to the resulting linear velocity. Have insufficient data available to
> do anything more.
Or, for his DC rated CFM where in the table does he fall as a starter?
If free air is insufficient volumetric flow, then it's clear it won't
with added restrictions.
--
On 03/02/2016 7:52 PM, OFWW wrote:
...
> This link might save you some time and trouble.
> http://hhrwoodworkingclub.org/Dust%20Collection%20System%20Design%2010%20April%2009.pdf
...
Oh, I see that's the technical data from Air Handling Systems; that's
one of the many pieces and does walk thru a process...being an engineer,
I'd intended to automate it and use the actual correlations behind their
tables instead...I get fixated on the details _behind_ the big picture. :)
--
On 03/05/2016 8:54 AM, krw wrote:
...
> That helps a lot. Thanks guys. I'll have to digest this some more.
> Maybe I don't have the problem I thought I did and can use a longer
> run (with blast gates). Do you happen to know of an easy way to
> measure the flow rate?
Easy in theory, the effort to measure it well enough to be meaningful
isn't trivial...doable, yes, but must be done w/ care. If you're
serious, read Bill Pentz's stuff...
<http://billpentz.com/woodworking/cyclone/Measurement.cfm#Testing%20Setup>
Generally you can get satisfactory results by the methods outlined
earlier to estimate pressure losses _providing_ the manufacturer of the
DC gives realistic data. That may or may not be a reasonable assumption
unfortunately.
--
On 03/06/2016 12:19 AM, dpb wrote:
...
> Generally you can get satisfactory results by the methods outlined
> earlier to estimate pressure losses _providing_ the manufacturer of the
> DC gives realistic data. That may or may not be a reasonable assumption
> unfortunately.
That is, computing pressure drops is pretty basic and reasonably
accurate from which the requirements can be estimated. Then you're
relying on the stated capacity of the chosen DC to actually match what
it performs at--if they'll supply an actual head curve other than just
total no resistance CFM you've got better chances the data are valid.
--
On 03/06/2016 8:59 AM, dpb wrote:
> On 03/06/2016 12:19 AM, dpb wrote:
> ...
>
>> Generally you can get satisfactory results by the methods outlined
>> earlier to estimate pressure losses _providing_ the manufacturer of the
>> DC gives realistic data. That may or may not be a reasonable assumption
>> unfortunately.
>
> That is, computing pressure drops is pretty basic and reasonably
> accurate from which the requirements can be estimated. Then you're
> relying on the stated capacity of the chosen DC to actually match what
> it performs at--if they'll supply an actual head curve other than just
> total no resistance CFM you've got better chances the data are valid.
Oh, also...as you'll note on the Pentz site, it's pretty concerned about
dust as opposed to simply chip collection. If you're after that level,
it'll take a _lot_ more CFM than the 350-400 at each tool that has been
the norm. That's shown in the tables there. I've not been terribly
concerned figuring there's far more grain dust and such from farming
that has no chance't of collecting than what I'll ever make from
sawdust... :) For others, have to make own decision on how strict to be
in comparison to commercial/OSHA/EEU guidelines.
--
On Sat, 05 Mar 2016 09:54:45 -0500, krw <[email protected]> wrote:
>On Wed, 02 Mar 2016 12:56:18 -0600, dpb <[email protected]> wrote:
>
>>On 02/29/2016 7:25 PM, krw wrote:
>>...
>>
>>> I was wondering more about the airflow resistance increase, though I
>>> can see where dust sticking to joints wouldn't help. Is there a
>>> significant air resistance difference between "clean" metal and
>>> "clean" PVC?
>>
>>For straight pipe, no. Where I was headed was that the fittings (el's,
>>wye's, etc.) associated with PVC are much tighter radius (even "long"
>>el's) than those used in "proper" dust collection and handling systems
>>and a single elbow is some 5X the dP of 100 ft of straight pipe whereas
>>for the metal ducting with 1.5 radius it's more like 1.5-2.0X. That
>>differential will more than make up for whatever minor improvement the
>>straight PVC might have over the galvanized.
>>
>>I've got quite a bit of data and design stuff from various sources but
>>haven't ever actually put it all together as a easy-to-use pattern w/o
>>being intimate w/ the details of what the various pieces mean -- stuff
>>like which friction-factor formulation goes with which pressure drop
>>correlation, etc., etc., ...
>>
>>Since I'm in the process of setting up a new area in the barn and will
>>have to do at least a modicum of this shortly, maybe this will be the
>>impetus to try to consolidate some of that to a more "handbooky" kind of
>>process...
>>
>>The upshot is, however, that you need to keep the sizes such that for
>>whatever CFM you have the linear velocity for branch lines of roughly
>>4000 fpm and 3500 fpm or so for main ducts. This will ensure won't have
>>issues w/ drop out and so on. If the chip sizes are small or dust like
>>a sander, you can get by w/ somewhat less; the above are targets for
>>that include planers, shapers, routers, etc., that make a fair-sized chip.
>>
>>Just for info, though, the difference in cfm required for 3500 fpm is
>>
>>3" 170
>>4" 300
>>5" 475
>>6" 600
>>
>>As you note, it goes up by the ratio of cross-section areas, obviously.
>> The fortunate thing is, of course that the percentage increase in area
>>decreases from step to step in uniform diameter increments so the
>>biggest jump is from 3" to 4"; 4" to 5" isn't quite as painful.
>>
>>Hopefully that helps..
>
>That helps a lot. Thanks guys. I'll have to digest this some more.
>Maybe I don't have the problem I thought I did and can use a longer
>run (with blast gates). Do you happen to know of an easy way to
>measure the flow rate?
You can make a U-Tube Manometer. It is the cheapest way I know of,
otherwise you can buy one, at an HVAC supply house or WW Graingers.
Measure the inches of water negative pressure, take the inside
diameter of the pipe you measured and compare it to a FPM chart on one
of the links I provided. It will require that you drill a hole to
connect the U-tube to, with no leakage while connected. I can find you
a how to on it if desired.
On Wed, 02 Mar 2016 12:56:18 -0600, dpb <[email protected]> wrote:
>On 02/29/2016 7:25 PM, krw wrote:
>...
>
>> I was wondering more about the airflow resistance increase, though I
>> can see where dust sticking to joints wouldn't help. Is there a
>> significant air resistance difference between "clean" metal and
>> "clean" PVC?
>
>For straight pipe, no. Where I was headed was that the fittings (el's,
>wye's, etc.) associated with PVC are much tighter radius (even "long"
>el's) than those used in "proper" dust collection and handling systems
>and a single elbow is some 5X the dP of 100 ft of straight pipe whereas
>for the metal ducting with 1.5 radius it's more like 1.5-2.0X. That
>differential will more than make up for whatever minor improvement the
>straight PVC might have over the galvanized.
>
>I've got quite a bit of data and design stuff from various sources but
>haven't ever actually put it all together as a easy-to-use pattern w/o
>being intimate w/ the details of what the various pieces mean -- stuff
>like which friction-factor formulation goes with which pressure drop
>correlation, etc., etc., ...
>
>Since I'm in the process of setting up a new area in the barn and will
>have to do at least a modicum of this shortly, maybe this will be the
>impetus to try to consolidate some of that to a more "handbooky" kind of
>process...
>
>The upshot is, however, that you need to keep the sizes such that for
>whatever CFM you have the linear velocity for branch lines of roughly
>4000 fpm and 3500 fpm or so for main ducts. This will ensure won't have
>issues w/ drop out and so on. If the chip sizes are small or dust like
>a sander, you can get by w/ somewhat less; the above are targets for
>that include planers, shapers, routers, etc., that make a fair-sized chip.
>
>Just for info, though, the difference in cfm required for 3500 fpm is
>
>3" 170
>4" 300
>5" 475
>6" 600
>
>As you note, it goes up by the ratio of cross-section areas, obviously.
> The fortunate thing is, of course that the percentage increase in area
>decreases from step to step in uniform diameter increments so the
>biggest jump is from 3" to 4"; 4" to 5" isn't quite as painful.
>
>Hopefully that helps..
That helps a lot. Thanks guys. I'll have to digest this some more.
Maybe I don't have the problem I thought I did and can use a longer
run (with blast gates). Do you happen to know of an easy way to
measure the flow rate?