I have received requests to post my observations about dust collection
to the WRECK for the benefit of the requesters and others readers of the
group.

I see a lot of discussion about bag-type dust collectors, overhead
dust filters, and trash-can separators. Most of these discussions
ignore the severe health hazards that come from not properly collecting
and processing the extremely fine dust that comes from table saws,
sanding, and other wooodworking activities.

I was looking for an inexpensive bag-type collector last year when
I encountered Bill Pentz's web site at

http://cnets.net/~eclectic/woodworki...lone/index.cfm

and read of his experience with severe asthma and his near-fatal encounter
with fine wood dust. My experience with cutting MDF on my Unisaw quickly
convinced me he was not exaggerating at all, and I decided to build a
cyclone using his design. I commend his site to everyone's careful
perusal. EVERY woodworker, serious or casual hobbyist, owes to himself
(or herself), spouse, family, and others to be well-informed about the
DANGERS to life and health that come from working with wood and being
around wood dust!

After working with Bill, who has done more research on the subject
than probably nearly anybody on planet earth, for much of the last
year, I have a radically broadened view of dust collection, and am
now manufacturing kit cyclones at his invitation that are based on
his exceptional design work. I am the only person authorized to do
so (other than if one builds his design for personal use):

( http://cnets.net/~eclectic/woodworki...larkesKits.cfm )

After firing up my own cyclone and actually using it, I have some
observations from the "real world".

AVOID AIR FILTER "SOLUTIONS"! Putting an air filter up to recirculate the
air and filter it as it passes through is like taking a 5-gallon bottle
of muddy water, pumping it through a filter at one pint per minute, then
returning the filtered water to the bottle. How long would it take for
the water to be perfectly clear if you have an agitator in the water that
keeps the dirt from settling out? With one water-change per 40 minutes,
how many water changes to get it all out? A very many! Yet that's
what you are doing to the air in your shop when you rely on an air filter
unit to clean up the air. It is virtually impossible to eliminate dust
from your shop air by using an overhead air filter. You might reduce
it, but the fine dust is more dangerous to your health than the course
dust caught by bag-type dust collectors!

The ONLY way to get rid of dust in the shop and properly protect your
lungs is to have an ADEQUATE collector that separates the dust from the
air (only cyclones can do this very well), then filters the air at not
more than 0.5 micron, or better yet, 0.3 or 0.2 micron with filters
that are at least 99.97% efficient. If the cyclone doesn't remove nearly
all of the micro-fine dust before it goes to the blower, the fine dust
will plug the filters in short order, and if it doesn't have especially
low static pressure loss through the cyclone, you won't have much
left to power the system, especially if you don't have a 14" blower that
can carry at least 1000 CFM against 9 or 10" of static pressure (which
requires a 5-HP motor, not a 1-1/2 or 2-HP blower -- you can't violate
the fundamental laws of physics).

A 10" table saw requires at least 900 CFM (500 CFM or more below
and 300 or more above) to capture enough air around the machine to
keep fine dust from getting into the external air in the room. The
dust-laden air can then be processed, cleaned and returned to the room
without filling the air with fine dust. (Bill's site has a page on the
required CFM for various kinds of tools and machines.)

The units I've been designing and manufacturing under license from Bill
Pentz use highly effective air-flow management to get the really fine
dust out inside the cyclone so it can be used with high-efficiency micro-fine
filters. The design also minimizes static pressure (some competing
cyclones have internal static-pressure drops ranging from 2-4 times
as much pressure loss as this design), and excessive static pressure
loss through the cyclone really damages the ability of the system
to perform as it must.

The cost for a complete installation of a quality system is about
what you'd pay for a new Kirby or Rainbow household vacuum cleaner, if
even that much. If a good system were to save a few weeks in the
hospital allow you to escape spending the rest of your life suffering
from asthma, allergies, emphysema, or cancer, it would be a priceless
value.

Whether you get my system or another is not important. What IS important
is that you take some serious time and really understand the importance
of doing the job RIGHT the first time (it's always cheaper that way in the
long run), even if you have to postpone buying some other neato tool
you just HAVE to have. Take a few hours and study the material on Bill's
site and get informed about the real issues related to dust collections,
and understand the principles behind proper dust collection before you
start spending your hard-earned cash.

If you have other questions, feel free to contact me by private email.

Clarke