I'm reading "Bill's Place" (Bill Pentz) and his writeups on what does or
doesn't constitute an effective dust collection system. He insists that
4" ducting is woefully inadequate for safe dust collection. He writes
that 6" is what is needed.
His writeup gets fairly technical and sounds very convincing. But of
course, using 6" ducting greatly increases the cost of the ducting for
Are there other opinions on this or do people pretty much agree that 4"
ducting is inadequate?
I converted from 4" to 6" after reading Bill's site. The flow is much
better, though I will need to convert to a cyclone in the near future.
To me, cost is irrelevant. We spend $1000's of dollars on our tools to
make this dust, that if we don't collect right at the source as soon as
it is generated, will end up in our lungs causing us untold health
problems. I say, spend a $1000 or so, forgo the upgrade on that tablesaw
or jointer, and ensure that we can continue woodworking for years to
come. Anything else seems like false economy to me!
mywebaccts (at) PLUGcomcast.net wrote:
On Sun, 22 Jan 2006 19:23:38 -0800, Joseph Connors
Well I tend to agree that 6 inches is much better (mine is 4)..BUT
honestly what did woodworkers like my father loose by spending years
in their shops without any DC's....? My Dad passed away in 2002 at
the age of 87.
I have had my DC system for at least 10 years most likely more BUT to
be truthful I never installed it for health reasons... NOPE..*I just
happen to like relaxing and working in a clean shop.. I retired
almost 8 years ago and have spent at least 3-4 hours in the shop every
day since ... a lot less then that when I was working naturally...
I'm sorry...but spending 1000's of dollars on DC systems for health
reasons to me is not really worth the effort BUT spending that same
amoput of money to increase your enjoyment of life (like a clean shop)
PLUS a more healthful envioroment IS WORTH IT
Will I change over to 6 in runs...??? Ya know I most likely will
BUT only because it would be an interesting project...
As far as your father is concerned, a number of factors are in play
here. Perhaps he did not a predisposition to an allergy or lung problem.
Lung problems run in my family. Another point is in the past there was a
lot less sanding done, especially by machine. They tended to plane and
scrape much more so the shop environment was healthier.
As far spending the money goes, everyone makes that decision for
themselves as to their priorities in life. Its a personal choice to
gamble that it won't happen to you.
Another factor, Bob, is the shop itself. If your shop is open to the
air, then air quality is less of a concern. These bags collectors with
small 4" pipe are dust pumps, pure and simple. When you watch them
inflate with sunlight in back of them, you can see the cloud of dust
As far as I'm concerned, you need a large blower with 6" pipe and very
good (<.5 micron - certified) filtration.
Bob G. wrote:
The size of the pipe is _completely_ orthogonal to the efficacy
of the collector bags. A given collector bag will produce the same
"cloud of dust" irrespective of the size of the ductwork.
So long as the chips and dust are being transported from the
machine to the collector, the size of pipe is far less important
than the quality and weave of the bag.
Typical garage shop, 4" is fine.
You hit the nail on the head! "So long as the chips and dust are being
transported from the machine to the collector" .... thats the whole
thing ... 4" pipe, in most applications, cannot carry enough volume of
air to transport the FINEST dust from the machine to the collector.
The vast majority of bags don't begin to achieve the necessary
I've spent a lot of time at Bill's Place too. The only question in my
mind is whether the nexus between occasional exposure to wood dust and
lung problems has been adequately established by the medical community.
I'm not arguing against it, I'm just not yet fully convinced.
I haven't done any controlled experiments like he did, but as an
engineer, I find no fault with his statements about what is necessary
to capture that fine dust that causes so much concern. I totally agree
that it's easy enough to collect the chips that you'd be sweeping off
the floor, but it requires much more air flow AT THE TOOL to capture
all the micro-particles. To move that much air, you need big blowers
and big pipes.
"Every man is my superior in that I can learn from him." - Thomas
On Sun, 22 Jan 2006 20:07:12 -0700, "mywebaccts (at) PLUGcomcast.net"
<"mywebaccts (at) PLUGcomcast.net"> wrote:
I agree that six inch piping is much better than 4, although a bit
less practical for a typical (home) workshop. Pi R squared shows 12
vs 27, meaning that the 6" pipe can move over twice the volume as the
4" pipe in any given time. Now whether the 4" piping is inadequate or
not depends on how quickly sawdust will be produced.
My workshop seems painfully small to accomodate a 6" ducting system. I
expect most of my work to be routing and scroll sawing and hence don't
think the dust problem will justify the expense of a 6" system.
Of course, it's dangerous to put a price on one's health. Lung problems
caused by inhalation of microfine particles is pretty nasty (so I've heard).
Some people have had allergic reactions to wood dust and no longer can
work wood. These reactions can come about after prolonged exposure, with
no obvious ill effects to breathing the dust, and all of a sudden they
either must wear a respirator or not work wood. If you have this genetic
trigger, it can happen right out of the blue with little or no warning.
4" pipe CAN work for some machines with a large enough blower. It
depends on a lot of factors. Its just for most machines and blowers, the
6" pipe is required.
mywebaccts (at) PLUGcomcast.net wrote:
And some people have allergic reactions to peanuts and can no longer
eat peanut butter. The vast majority of people who have and do work
with wood don't have allergic reactions. Don't blow the problem all
out of proportion.
And whether or not you use dust collection won't prevent it, unless you
have _perfect_ dust collection, which is probably unachievable (no hand
sanding, let someone else empty the collector, vacuum the shop floor
ten times daily, etc.).
In an industrial setting, perhaps. For a home shop?
That is true as far domestic woods are concerned ... not true at all for
exotics. Allergic reactions can develop over time ... the more exposure,
the sooner it can happen. Also, wood dust is a know carcinogen.
But you are right in that most of the time allergic reactions are not
going to be the problem. Lung problems are the main issue and that takes
time and exposure.
It most certainly will prevent it. You do not need PERFECT dust
collection, which I agree is probably unachievable in a practical sense,
just reducing the exposure will suffice. I'm not saying that one whiff
of wood dust and it off to the pulmonary care unit ... we're talking
reasonable precautions here.
Where the shop is physically located is irelevent. The
pipe/blower/filtration combination is what matters.
You may wish to also consider the *amount* of exposure. Most hobbyists
do not spend 7-8hrs a day in the shop. Many professionals could.
In a case like this, the hobbyist may realistically decide that a 4"
system is better than nothing, but that the 6" system isn't worth the
Personally, I do software for a living. I am *far* more picky about the
quality of my monitor/chair/desk than most people, because I spend so
much time there.
On the other hand, my current dust collection strategy is a shopvac and
a face mask because I might spend an hour a week actually making dust.
I hear what you're saying. I understand though from Bill's site that
some studies have indicated that the typical hobbiest woodworker has
more exposure than large industrial settings because the size of the
particles involved are smaller in a hobby situation than in an
industrial one. With the large industrial settings the bag house is
located outside and therefore no threat to air quality at all, whereas
in a small shop the air is recirculated.
Chris Friesen wrote:
Good point. I'm not sure that 5" piping and connectors are easy to come
by in my are (Los Alamos, NM). All I've seen is the 4" and the 6". But
I'll check in Santa Fe. That might be a nice compromise.
"mywebaccts (at) PLUGcomcast.net" <"mywebaccts (at) PLUGcomcast.net"> wrote
5" is probably more difficult to come by in most places. I'm in ABQ and
while I haven't specifically looked for pipe for my DC yet, I tend to see
only 4" and 6". I'm sure 5" is available from the plumbing supply houses
but it probably costs a bit more. I should have said I'm looking at the
PVC S&D piping. I'm in the process of designing a new shop to build when I
get some time and money and plan to do 6" under the floor with a cyclone
(Bill's Airfoil design) but right now I'm working in my garage where I have
no room for a cyclone or piping. I'll keep an eye out here in town to see
if 5" is more prevalent than I remember and let ya know. I head up to
Angel Fire on a fairly regular basis and we could arrange to meet somewhere
if you wanted me to pick it up.
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