I have used a single 50 flex 4" diameter flex dust collection tubing
(with an internal steel grounded wire) for all my machines for the
past 15 years but now it is wearing out with many small holes. I have
a 1.5 HP DC with a trash can cyclone. Are there any recommendations
for replacement? I was looking at T-7 Santoprene tubing which is
supposed to be good at abrasion and contains a steel wire which I can
ground. It is about $4.50 a foot. Is this a good choice/value?

"Phisherman" wrote in message
...
I was looking at T-7 Santoprene tubing which is
supposed to be good at abrasion and contains a steel wire which I can
ground. It is about $4.50 a foot. Is this a good choice/value?

Rigid PVC for the long runs is a hell of a lot cheaper. Use the flex for
connections and drops to the machines. .

This may be of interest,check it out, I have it and like it a lot!

http://www.harborfreight.com/cpi/cta...emnumber=47911

Good luck

Jim






"Edwin Pawlowski" wrote in message
m...

"Phisherman" wrote in message
...
I was looking at T-7 Santoprene tubing which is
supposed to be good at abrasion and contains a steel wire which I can
ground. It is about $4.50 a foot. Is this a good choice/value?

Rigid PVC for the long runs is a hell of a lot cheaper. Use the flex for
connections and drops to the machines. .

Edwin,
One of the recent wood mags (not sure which one) says PVC is not good
for DC. Just can't remember why not. I know it's easy to just glue up
and you're ready, but I would like to know why PVC won't work.
Mark L.

Edwin Pawlowski wrote:
"Phisherman" wrote in message
...

I was looking at T-7 Santoprene tubing which is
supposed to be good at abrasion and contains a steel wire which I can
ground. It is about $4.50 a foot. Is this a good choice/value?


Rigid PVC for the long runs is a hell of a lot cheaper. Use the flex for
connections and drops to the machines. .

"Mark L." wrote in message
news
Edwin,
One of the recent wood mags (not sure which one) says PVC is not good
for DC. Just can't remember why not. I know it's easy to just glue up
and you're ready, but I would like to know why PVC won't work.
Mark L.

Because people will lead you to believe that if you use non-grounded plastic
there will be an explosion bigger than the H-bomb.

Where I work, we move 20,000 pounds of material a day through 4" pvc.
Probably half of our industry does. I use pvc in my shop with good
results. Just emptied the DC last night, in fact.
Ed

http://pages.cthome.net/edhome

In article ,
"Edwin Pawlowski" wrote:

"Mark L." wrote in message
news
Edwin,
One of the recent wood mags (not sure which one) says PVC is not good
for DC. Just can't remember why not. I know it's easy to just glue up
and you're ready, but I would like to know why PVC won't work.
Mark L.

Because people will lead you to believe that if you use non-grounded plastic
there will be an explosion bigger than the H-bomb.

Where I work, we move 20,000 pounds of material a day through 4" pvc.
Probably half of our industry does. I use pvc in my shop with good
results. Just emptied the DC last night, in fact.
Ed

http://pages.cthome.net/edhome

I hope you grounded that posting before you hit the send button. I
don't want any of your static blowing up my hard drive.

On Mon, 12 Jul 2004 01:30:11 GMT, "Mark L."
wrote:

Edwin,
One of the recent wood mags (not sure which one) says PVC is not good
for DC. Just can't remember why not. I know it's easy to just glue up
and you're ready, but I would like to know why PVC won't work.
Mark L.






it will explode....



GD&R

"Edwin Pawlowski" wrote in message
. ..


Where I work, we move 20,000 pounds of material a day through 4" pvc.
Probably half of our industry does. I use pvc in my shop with good
results. Just emptied the DC last night, in fact.
Ed

http://pages.cthome.net/edhome



You are still alive?You should have blown up long ago!! ;-)
Greg

On the show " Ultimate Workshop" on the DIY network they said that the =
flex hose slows down the air current thus robbing power from your DC.
Puff

"Phisherman" wrote in message =
...
I have used a single 50 flex 4" diameter flex dust collection tubing
(with an internal steel grounded wire) for all my machines for the
past 15 years but now it is wearing out with many small holes. I have
a 1.5 HP DC with a trash can cyclone. Are there any recommendations
for replacement? I was looking at T-7 Santoprene tubing which is
supposed to be good at abrasion and contains a steel wire which I can
ground. It is about $4.50 a foot. Is this a good choice/value?

"Mark L." wrote in message
news
and you're ready, but I would like to know why PVC won't work.


Remember that guy who strapped a JATO to his Chevy Impala out in AZ? He was
a woodworker too, had ungrounded PVC dust collection in shop. It blew up one
day.

On Mon, 12 Jul 2004 15:21:40 GMT, "patrick conroy"
wrote:

|
|"Mark L." wrote in message
|news |
| and you're ready, but I would like to know why PVC won't work.
|
|
|Remember that guy who strapped a JATO to his Chevy Impala out in AZ? He was
|a woodworker too, had ungrounded PVC dust collection in shop. It blew up one
|day.
|

Folks, PVC is an insulator. You CAN NOT GROUND an insulator. If you
could, you would not be reading this message because none of our
computers (or anything else electronic) would be working.

Repeat after me:

"I cannot ground PVC"
"I cannot ground PVC"
"I cannot ground PVC"
"I cannot ground PVC"
"I cannot ground PVC"
"I cannot ground PVC"
"I cannot ground PVC"
"I cannot ground PVC"
......

I thought it was some kind of a commie plot..... So 4" PVC it is :-)

Edwin Pawlowski wrote:


Because people will lead you to believe that if you use non-grounded plastic
there will be an explosion bigger than the H-bomb.

Where I work, we move 20,000 pounds of material a day through 4" pvc.
Probably half of our industry does. I use pvc in my shop with good
results. Just emptied the DC last night, in fact.
Ed

http://pages.cthome.net/edhome

"Mark L." wrote:
Edwin,
One of the recent wood mags (not sure which one) says PVC is not good
for DC. Just can't remember why not. I know it's easy to just glue up
and you're ready, but I would like to know why PVC won't work.

Well, some believe that the PVC can accumulate static electricity,
then discharge (by means of a little electrical arc) and ignite the
dust, thereby causing your own rendition of a grain silo explosion.

These are probably the same people who turn off their cell phones when
the fill up their cars with gas to prevent the deaded "cell-phone gas
station explosion"; because... well... gosh... even though we've never
tracked down a documented/verified case of it happening, it *must*
happen a lot because everyone talks about it, right?

Ugh. That's it! I'm submitting this one to MythBusters
(http://dsc.discovery.com/fansites/my...thbusters.html).

To answer your question, the May 2003 issue of American Woodworker
(page 54) has a section on setting up DC in your shop. The guy
suggests using steel instead of PVC for a variety of reasons. *One* of
the reasons is static buildup... but even then, the guy doesn't say
that there will be an explosion. He merely talks about the zap you can
get *yourself*. The other reasons are that steel comes in larger
diameters than the 4" where PVC generally stops at.

Strangely, he didn't mention how great steel looks when you
accidentally bump a tool into and dent it... or how yummy it feels
when you slice your hand on the sharp steel ends... or how the
sheetmetal screws protruding into the tube help the airflow!

He does point out though that, at large diameters, the price
difference between PVC and steel starts to become a non-factor in the
decision process.

Issue 13 of ShopNotes has an article about building your own cyclone
and collector. The seem to use all steel.

I recall reading some article about a week ago where the author went
into 4 more-likely fire hazards in your DC system than static
electricity. One of them was hitting a nail (or other metal) which can
cause red-hot sparks to go wafting through your DC system to the
collection bag. There were a couple of others. If I track down that
article, I'll come back and post it here.

"Edwin Pawlowski" wrote:

Because people will lead you to believe that if you use non-grounded plastic
there will be an explosion bigger than the H-bomb.

Actually, it just occured to me that you *can* purchase
electrically-conductive paint... probably in a spray, too. So you
could make your PVC system grounded without needing wires in it.

.... for those so concerned about grounding, that is.

- Joe

On 12 Jul 2004 21:50:11 -0700, (Joe Emenaker) wrote:


snip post about how pvc isn't a static explosion hazard, but metal
duct is better anyway.


I recall reading some article about a week ago where the author went
into 4 more-likely fire hazards in your DC system than static
electricity. One of them was hitting a nail (or other metal) which can
cause red-hot sparks to go wafting through your DC system to the
collection bag.

wouldn't metal duct (or more likely the sheet metal screws) present a
lot more opportunities for bits of hard stuff like chips of metal or
pebbles from the shop floor to strike sparks? of course the big one is
still gonna be the impeller blades themselves....

On 12 Jul 2004 21:52:32 -0700, (Joe Emenaker) wrote:

"Edwin Pawlowski" wrote:

Because people will lead you to believe that if you use non-grounded plastic
there will be an explosion bigger than the H-bomb.

Actually, it just occured to me that you *can* purchase
electrically-conductive paint... probably in a spray, too. So you
could make your PVC system grounded without needing wires in it.


but you cannot, repeat cannot ground the cloud of dust. grounding the
duct is like putting your belt on under your pants. it's a stupid
waste of time.





... for those so concerned about grounding, that is.

- Joe

After the zinc is gone, perhaps.

One more reason for dropping the shavings before stuffing dust through the
impeller.

Question, isn't duct tape good enough, that folks use sheet metal screws?

wrote in message
...
On 12 Jul 2004 21:50:11 -0700, (Joe Emenaker) wrote:


wouldn't metal duct (or more likely the sheet metal screws) present a
lot more opportunities for bits of hard stuff like chips of metal or
pebbles from the shop floor to strike sparks? of course the big one is
still gonna be the impeller blades themselves....

On Tue, 13 Jul 2004 07:06:04 -0400, "George" george@least wrote:

After the zinc is gone, perhaps.

One more reason for dropping the shavings before stuffing dust through the
impeller.

Question, isn't duct tape good enough, that folks use sheet metal screws?

FWIW, I highly recommend metal tape versus duct tape - at least from the
standpoints of being a much better seal and the tape not delaminating from
the adhesive layer after some time. The metal tape is more expensive. But
a regular HVAC duct with metal tape at the seams and the joints, if you
want, is darn "airtight" in this context, IMO. The metal tape won't handle
bumps and such as well, so in some places you could use duct tape over the
metal tape. -- Igor

"Wes" wrote in message
...

Repeat after me:
"I cannot ground PVC"

Can I just sit in detention instead?

In article ,
Wes wrote:

On Mon, 12 Jul 2004 15:21:40 GMT, "patrick conroy"
wrote:

|
|"Mark L." wrote in message
|news |
| and you're ready, but I would like to know why PVC won't work.
|
|
|Remember that guy who strapped a JATO to his Chevy Impala out in AZ? He was
|a woodworker too, had ungrounded PVC dust collection in shop. It blew up one
|day.
|

Folks, PVC is an insulator. You CAN NOT GROUND an insulator. If you
could, you would not be reading this message because none of our
computers (or anything else electronic) would be working.

Repeat after me:

"I cannot ground PVC"
"I cannot ground PVC"
"I cannot ground PVC"
"I cannot ground PVC"
"I cannot ground PVC"
"I cannot ground PVC"
"I cannot ground PVC"
"I cannot ground PVC"
.....

Yes, PVC is more a dielectric. That said, one puts wire through the
ducts so that it "collects" the charge that is generated by the movement
of the air/wood through the duct. You ground the wire to dissipate the
"static charge".

So while PVC doesn't "conduct", it can generate "Static electricity"
under the right circumstances. That is what you're collecting and
grounding.
--
Thanks,

Ham

How many places per foot do you have to anchor the ground wire to the PVC to
dissipate the charge?

Hint. This is a trick question.

"Bob Brogan" wrote in message
...
In article ,

Yes, PVC is more a dielectric. That said, one puts wire through the
ducts so that it "collects" the charge that is generated by the movement
of the air/wood through the duct. You ground the wire to dissipate the
"static charge".

So while PVC doesn't "conduct", it can generate "Static electricity"
under the right circumstances. That is what you're collecting and
grounding.
--

On Tue, 13 Jul 2004 14:39:24 -0400, "George" george@least wrote:

How many places per foot do you have to anchor the ground wire to the PVC to
dissipate the charge?

Hint. This is a trick question.


an infinite number.......









"Bob Brogan" wrote in message
...
In article ,

Yes, PVC is more a dielectric. That said, one puts wire through the
ducts so that it "collects" the charge that is generated by the movement
of the air/wood through the duct. You ground the wire to dissipate the
"static charge".

So while PVC doesn't "conduct", it can generate "Static electricity"
under the right circumstances. That is what you're collecting and
grounding.
--

Precisely. Which, I suppose, is tantamount to saying the wire is
ineffective.

My 4" hose has a wire helix inside, and it grows dust in the winter.

Check the tables here for some good info.
http://www.esdsystems.com/training/staticgeneration.htm

wrote in message
...
On Tue, 13 Jul 2004 14:39:24 -0400, "George" george@least wrote:

How many places per foot do you have to anchor the ground wire to the PVC
to
dissipate the charge?

Hint. This is a trick question.


an infinite number.......

On Tue, 13 Jul 2004 18:04:09 GMT, Bob Brogan wrote:



So while PVC doesn't "conduct", it can generate "Static electricity"
under the right circumstances. That is what you're collecting and
grounding.


nope.

In article ,
wrote:

On Tue, 13 Jul 2004 18:04:09 GMT, Bob Brogan wrote:



So while PVC doesn't "conduct", it can generate "Static electricity"
under the right circumstances. That is what you're collecting and
grounding.


nope.

Yup.
--
Thanks,

Ham

Ummm...yes, you can ground an insulator. Many people working in dry climates
have been zap'ed from the generated static, and they've used wire or other
methods to ground it out. Try using a comb or glass rod to generate static,
then discharge one end.. You'll find there's little if any static charge left
on the rest of it. Static charges do not propagate with the same mechanism as
an electric current in a conductor.
For static buildup on pvc you can:
1- Move it out of reach.
2- Wrap a wire (very small; current is low) around and ground it.
3- Spray lightly with conductive paint and ground one end.
GerryG

On Mon, 12 Jul 2004 10:38:00 -0700, Wes wrote:

On Mon, 12 Jul 2004 15:21:40 GMT, "patrick conroy"
wrote:

|
|"Mark L." wrote in message
|news |
| and you're ready, but I would like to know why PVC won't work.
|
|
|Remember that guy who strapped a JATO to his Chevy Impala out in AZ? He was
|a woodworker too, had ungrounded PVC dust collection in shop. It blew up one
|day.
|

Folks, PVC is an insulator. You CAN NOT GROUND an insulator. If you
could, you would not be reading this message because none of our
computers (or anything else electronic) would be working.

Repeat after me:

"I cannot ground PVC"
"I cannot ground PVC"
"I cannot ground PVC"
"I cannot ground PVC"
"I cannot ground PVC"
"I cannot ground PVC"
"I cannot ground PVC"
"I cannot ground PVC"
.....

"Puff Griffis" wrote:
On the show " Ultimate Workshop" on the DIY network they said that the
flex hose slows down the air current thus robbing power from your DC.

Yeah. I'm expecting a Delta 1.5hp DC for my birthday next month, and
so I'm doing a lot of reading on how to "duct-up" the shop. Almost all
of the articles seem to be in agreement on the following principles:

o 4" is good. 5" is gooder. 6" is gooderer.
o Try to avoid any hose/tubing that's not smooth inside.
o Try to avoid tight turns (ie, use 45-degree bends instead of
90-degree).
o For the same reason to avoid tight turns, avoid right-angle "T"
joints and opt for the "fork-in-the-road" style "Y"s.

I'm taking so much of this as religion that my current dillema is
this. I'm also planning on building the home-made cyclone in
ShopNotes, but its outlet is at the top and the DC that it feeds into
is going to have its inlet either waist-high or at the floor. So, I'm
debating either raising the DC onto a platform or modifying the
cyclone design so that I can get a more-or-less straight shot across
from the cyclone exhaust to the DC intake.

- Joe

On 15 Jul 2004 15:19:48 -0700, (Joe Emenaker) wrote:

"Puff Griffis" wrote:
On the show " Ultimate Workshop" on the DIY network they said that the
flex hose slows down the air current thus robbing power from your DC.

Yeah. I'm expecting a Delta 1.5hp DC for my birthday next month, and
so I'm doing a lot of reading on how to "duct-up" the shop. Almost all
of the articles seem to be in agreement on the following principles:

o 4" is good. 5" is gooder. 6" is gooderer.

This comment is not to you so much as to a number of people here who say
that bigger is better with ducts. I can see that as a general proposition,
but at some point, relative to the size of the fan, won't velocity suffer
in a significant way? And, doesn't velocity have a role to play in an
effective DC system? After all, we are not just talking about air -- also
talking about moving solid waste. Or, as is sometimes the case, am I
missing something here? -- Igor

igor said:

"Puff Griffis" wrote:

o 4" is good. 5" is gooder. 6" is gooderer.

This comment is not to you so much as to a number of people here who say
that bigger is better with ducts. I can see that as a general proposition,
but at some point, relative to the size of the fan, won't velocity suffer
in a significant way? And, doesn't velocity have a role to play in an
effective DC system? After all, we are not just talking about air -- also
talking about moving solid waste. Or, as is sometimes the case, am I
missing something here? -- Igor

You are correct. When velocity drops too low, you cannot maintain the
material in suspension - it just builds up in the pipes instead of
flowing to the DC/pre-collector.


Greg G.

On 15 Jul 2004 15:19:48 -0700, (Joe Emenaker) wrote:

"Puff Griffis" wrote:
On the show " Ultimate Workshop" on the DIY network they said that the
flex hose slows down the air current thus robbing power from your DC.

Yeah. I'm expecting a Delta 1.5hp DC for my birthday next month, and
so I'm doing a lot of reading on how to "duct-up" the shop. Almost all
of the articles seem to be in agreement on the following principles:

o 4" is good. 5" is gooder. 6" is gooderer.

Maybe. It really depends upon distance and the size of your dust
collector. 6" may be *too* good and reduce velocity to the point where
chips settle out. You really need to do the velocity/static pressure
computations to be sure. In my case, 6" was too large, 5" was the ideal
size. Unfortunately, that meant I could not use cheap PVC from the Borg.

o Try to avoid any hose/tubing that's not smooth inside.
o Try to avoid tight turns (ie, use 45-degree bends instead of
90-degree).

Yep

o For the same reason to avoid tight turns, avoid right-angle "T"
joints and opt for the "fork-in-the-road" style "Y"s.


Again, yep

I'm taking so much of this as religion that my current dillema is
this. I'm also planning on building the home-made cyclone in
ShopNotes, but its outlet is at the top and the DC that it feeds into
is going to have its inlet either waist-high or at the floor. So, I'm
debating either raising the DC onto a platform or modifying the
cyclone design so that I can get a more-or-less straight shot across
from the cyclone exhaust to the DC intake.

- Joe

Check out the various web sites like
http://cnets.net/~eclectic/woodworking/cyclone/
it has an Excel spreadsheet:
http://billpentz.com/woodworking/cyclone/StaticCalc.xls that is invaluable
in sizing your system. Pay attention as well to sizing the ductwork for
each machine.

I just went through this late last year and have been very satisfied with
the results. I wound up buying metal spiral pipe from a local fabricator
along with Y's, T's and elbows. I can now see plumes of dust being sucked
into the table saw through the insert and the shaper table chips are sucked
into the system with few residuals left behind.

On Thu, 15 Jul 2004 22:58:20 GMT, igor wrote:

On 15 Jul 2004 15:19:48 -0700, (Joe Emenaker) wrote:

"Puff Griffis" wrote:
On the show " Ultimate Workshop" on the DIY network they said that the
flex hose slows down the air current thus robbing power from your DC.

Yeah. I'm expecting a Delta 1.5hp DC for my birthday next month, and
so I'm doing a lot of reading on how to "duct-up" the shop. Almost all
of the articles seem to be in agreement on the following principles:

o 4" is good. 5" is gooder. 6" is gooderer.

This comment is not to you so much as to a number of people here who say
that bigger is better with ducts. I can see that as a general proposition,
but at some point, relative to the size of the fan, won't velocity suffer
in a significant way? And, doesn't velocity have a role to play in an
effective DC system? After all, we are not just talking about air -- also
talking about moving solid waste. Or, as is sometimes the case, am I
missing something here? -- Igor


you're not missing something. the bigger the duct the bigger the
collector you need to have sucking on it. if the duct is
oversize/collector is undersize sawdust will settle out in the duct.

I... (Joe Emenaker) wrote:

I recall reading some article about a week ago where the author went
into 4 more-likely fire hazards in your DC system than static
electricity.

I found it!

Fine Woodworking's "Tools & Shops" issue Winter 2001/2002.

On page 48, Rod Cole (a MIT professor who's office is next an MIT prof
who happens to be an expert in the physics of lightning), wrote an
article called "PVC Pipe Dangers Debunked". He makes reference to an
even more exhaustive report on the web. I searched Google for "Rod
Cole PVC" and found this:

http://mywebpages.comcast.net/rodec/.../DC_myths.html

Enjoy!

- Joe

I wouldn't worry. After making the way clear (and, as noted, maintaining
pressure) for dust and chips on the way to the cyclone, it's only air you'll
want to move to the impeller. It's a fluid, not a solid.

"Joe Emenaker" wrote in message
om...

I'm taking so much of this as religion that my current dillema is
this. I'm also planning on building the home-made cyclone in
ShopNotes, but its outlet is at the top and the DC that it feeds into
is going to have its inlet either waist-high or at the floor. So, I'm
debating either raising the DC onto a platform or modifying the
cyclone design so that I can get a more-or-less straight shot across
from the cyclone exhaust to the DC intake.

- Joe

igor wrote:

.... to a number of people here who say
that bigger is better with ducts. I can see that as a general proposition,
but at some point, relative to the size of the fan, won't velocity suffer
in a significant way?

I was thinking the same thing myself. In one of the downloadable
reviews of dust collectors that are available at WoodStore, they
mention that you need a certain number of feet-per-second of air
movement in order to keep the sawdust suspended. They use that as
justification for why you need "xyz" amount of cubic feet per minute
from your DC.

The first question that ran through my mind was "Why don't you just
decrease the diameter of your hose?". If you just went from 4" to 3",
the velocity of the air inside the hose (provided that your CFM didn't
suffer too much because of it) would go up by 60%!!!

Of course, there's also the other extreme. You don't want to hook up
half-inch pipe as your ducting, either, because the CFM will suffer so
much at that point that, even the small diameter probably won't help
the linear velocity of the air (and you'd have the new problem of not
drawing enough CFM from the *tool* itself ...).

Where the magic cross-over point is depends upon the CFM of your DC,
how long and curvy your ducting is, and how resistant to airflow the
inside surface of your ducting is.

- Joe

Joe Emenaker wrote:

igor wrote:

.... to a number of people here who say
that bigger is better with ducts. I can see that as a general
proposition, but at some point, relative to the size of the fan, won't
velocity suffer in a significant way?

I was thinking the same thing myself. In one of the downloadable
reviews of dust collectors that are available at WoodStore, they
mention that you need a certain number of feet-per-second of air
movement in order to keep the sawdust suspended. They use that as
justification for why you need "xyz" amount of cubic feet per minute
from your DC.

The first question that ran through my mind was "Why don't you just
decrease the diameter of your hose?". If you just went from 4" to 3",
the velocity of the air inside the hose (provided that your CFM didn't
suffer too much because of it) would go up by 60%!!!

But you'd also get more clogs. 3" is getting down to the shop-vac hose
territory.

Of course, there's also the other extreme. You don't want to hook up
half-inch pipe as your ducting, either, because the CFM will suffer so
much at that point that, even the small diameter probably won't help
the linear velocity of the air (and you'd have the new problem of not
drawing enough CFM from the *tool* itself ...).

Where the magic cross-over point is depends upon the CFM of your DC,
how long and curvy your ducting is, and how resistant to airflow the
inside surface of your ducting is.

- Joe

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)

Not an engineer, but imagine the optimum transport pipe is probably ~5".
Force/unit area calcs show 6" less than half the four.

"Joe Emenaker" wrote in message
om...
igor wrote:

.... to a number of people here who say
that bigger is better with ducts. I can see that as a general
proposition,
but at some point, relative to the size of the fan, won't velocity
suffer
in a significant way?


Where the magic cross-over point is depends upon the CFM of your DC,
how long and curvy your ducting is, and how resistant to airflow the
inside surface of your ducting is.

- Joe

In article ,
says...
igor wrote:

This comment is not to you so much as to a number of people here who say
that bigger is better with ducts. I can see that as a general proposition,
but at some point, relative to the size of the fan, won't velocity suffer
in a significant way? And, doesn't velocity have a role to play in an
effective DC system? After all, we are not just talking about air -- also
talking about moving solid waste. Or, as is sometimes the case, am I
missing something here? -- Igor

You are actually right on target. Most of the various schemes I've
found for plumbing a single user home shop seem to optimize around a 1
1/2 to 2 HP collector and five inch pipe. Four inch pipe is too
restrictive, six inch pipe slows the velocity too much. So I tend to
get frustrated with all the woodworking suppliers that stock only four
inch pipe, hose and fittings.

So until I can find a big enough crowbar for my wallet, I am still
dragging around the forty feet of four inch flex that came with my
Penn State collector.

But if your running a one man shop, and running only one machine at a
time, does it really matter if the main runs are 4" or 5"? I've got a
delta 1.5 HP DC in my garage shop. I use 4" PVC sewer and drain pipe for
the main runs and flex pipe to the machines. The delta has 2 4" mains
coming off it so I ran 2 runs on each side of the shop. I don't have any
problems with airflow even to the farthest machine, which is a planer.
The PVC was cheap and easy to work. I also didn't bother to ground it
although is does develop some static when I run the planer or jointer.
But I look at it as a dust filter. The suspended dust in the shop sticks
to the pipe. I just vacuum it once in a while.

Just my 2cents.

In article , "George" george@least
wrote:

Not an engineer, but imagine the optimum transport pipe is probably ~5".
Force/unit area calcs show 6" less than half the four.

Perhaps someone can point out the error of my thinking on this subject...

The system can only flow as much as the smallest port in the factory
design. Take my Jet 1.5hp for example, what I'm getting at is that the
port and hose from the blower housing to the bag hanging ring is, I
believe, 5" diameter. To my thinking whatever size of the system outside
of the factory setup is limited by this 5" - in other words, one can't
fully draw 6" of main trunk air before the blower through a 5" hose
after the blower - therefore the appropriate size of the main trunk
should be no larger than 5" - or whatever the size of the smallest port
in the manufactured assembly.

Wadya think?

--
Owen Lowe and his Fly-by-Night Copper Company

"Fly-by-Night CC" wrote in message

The system can only flow as much as the smallest port in the factory
design. Take my Jet 1.5hp for example, what I'm getting at is that the
port and hose from the blower housing to the bag hanging ring is, I
believe, 5" diameter. To my thinking whatever size of the system outside
of the factory setup is limited by this 5" - in other words, one can't
fully draw 6" of main trunk air before the blower through a 5" hose
after the blower - therefore the appropriate size of the main trunk
should be no larger than 5" - or whatever the size of the smallest port
in the manufactured assembly.

Wadya think?

Has to do with velocity. I'm sure others can explain it better. Let's say
your blow has a true capacity of 1000 cfm. It will take in and blow out
1000 cubic feet every minute. If there is no duct at the entrance it will
suck air from any place in the room it can. As you get closer to the blower
you will feel the air moving. The more you restrict the opening, you will
feel the air moving faster. The blower sucks in the air and puts it into a
smaller outlet space and thus adds more force to the air and it moves faster
on the way out. Ducting allows you to concentrate and "aim" the point of
suction.

The blower can move 1000 cfm, but your compressor can make only 4 or 6 cfm,
but when you glow that amount of air through a small nozzle, it feels like a
lot more pressure than the outside of a fan or blower moving much more air.
If the blower did not have enough velocity, the dust would just fall on the
other side and not get moved into the bag. A window fan of the same
capacity with not ducting will move little dust by comparison because it h
as the cfm capacity, but at a much lower velocity.
Ed

Italian fellow name of Bernoulli, I believe, has some good words to say on
the subject.

Consider the original force per unit area I mentioned. That's where the
term PSI comes in. You can haul more air through a larger pipe, but the
pressure drops, because you're not capable of real compression through the
open sides of the impeller. This means that what's being carried along with
the air will also drop. Reverse is also pretty true. Take your 4" hose,
as I often do, and use a standard shop-vac adapter to 2", and notice you can
pick up pencils, chunks of scrap, and even the bolt you dropped, and were
looking for. Don't be frustrated and think you'll have to rummage through
the cyclone, those things are just upstream of the adapter, if they made it
that far, where there is no longer enough force/unit to carry them into the
bin. I rely on this when looking for dropped objects in my shop.

As mentioned, the "standard" unit now moves 1200/CFM at (some PSI) or in
reality, at some vacuum, measured in feet of water, inches/millimeters of
mercury or furlongs per fortnight. Now since the old 650 CFM @ 8 types were
the standard which spawned the 4" hose, I'm speculating that a 5" hose may
be best for the 1200, because the impellers are still pretty leaky, if you
read the mfrs specs. A 6" hose, as mentioned, would be 2 1/3 or so times
the area of a 4, negating the additional chip-carrying power.

Oh yes, don't ask about 2" hose and 2" sanding discs for the lathe. Makes
me veeery angry.

"Fly-by-Night CC" wrote in message
news
In article , "George" george@least
wrote:

Not an engineer, but imagine the optimum transport pipe is probably ~5".
Force/unit area calcs show 6" less than half the four.

Perhaps someone can point out the error of my thinking on this subject...

The system can only flow as much as the smallest port in the factory
design. Take my Jet 1.5hp for example, what I'm getting at is that the
port and hose from the blower housing to the bag hanging ring is, I
believe, 5" diameter. To my thinking whatever size of the system outside
of the factory setup is limited by this 5" - in other words, one can't
fully draw 6" of main trunk air before the blower through a 5" hose
after the blower - therefore the appropriate size of the main trunk
should be no larger than 5" - or whatever the size of the smallest port
in the manufactured assembly.

Wadya think?