Re: Pardon my dust (collection)

Dust collection is a simple matter for the work we do.

the most effective method of collection is at the point of
generation. ie: the cutting tip. if you can connect almost any kind
of flexable hose and a simple skirt around your cutter you will pull
95% of the offending stuff out.

There are two measurements to watch for if filtering. one is that
some particles are large enough for your resparatory system to handle
and pass, and then there are some that are small enought to pass.
There is that sweet spot in between where stuff stays there and makes
a mess. This is a property of the material. Each material has it's
own size so your research is needed on what you are using.

This is like a car filter. sub-micron dust in a car intake will get
trapped and washed away by the oil, but when a particle is large
enought to bridge the oil film wall, it will destroy a motor in
minutes. A car filter will stop everything ABOVE a certan size and
let EVERYTHING below that size pass.

The water bubblier scrubber I use is for particles that will adsorb
water. ie wood, ash and paper. it will not work as well on aluminum
and hardly at all on things that shed water.

The idea of the scrubber tower, a 6 ft tall 6 inch dia PVC pipe with
multiple sprinkler heads is to let the air flow with dust, and let
the dust get wet and therby increase the mass of the unit and then
wash away. a slow vertical air flow is needed, so the 'hang time'
the time the particle in question is in the vertical is long and it's
exposure to the mist is long. There are a lot of equasions for this
and many different methods. suffice it to say that at 1,400 feet per
minute vertical velocity (7.11 meter/sec) water drops will become
boyant. Mist will easily flow up, but above that 1,400 actual water
drops will start to rise.

A second method of catching fine dust is a filled scrubber stack.
this could be a stack filled with ping-pong balls and a sprinkler
feeding a lot of water flowing over them. The huge surface area is
the method of collection.

Neither of these methods is expensive, you should be able to put one
in your shop for less than $100.00, less if you can salvage some
parts. What you are collecting is MOST of the dust in the air. Only
a totally enclosed machineing center will let you catch it all.

Pur your shop vac in a box with two sheets of 1/2 drywall to contain
the noise (mass stops noise) and remember sound travels at the line
if sight, in straight lines. it will bounce though. So seal that
box tight. Exhaust could be outisde, great for many reasons, noise
is one, those tiny particles is another. They will fall out. and
don't worry about your car paint. what we do is not going to attack
the paint, make it dusty? maybe.

And if you want to make the Mrs. happy and spend lots of money, put
in a central vac, hepa and external exhaust. Now there goes a few
grand.

OH and a simple note here about the dirty water, asbestos and other
long stringy materials, fiiberglass and such lose all of their danger
when wet. it is the dust that is the problem. so your dirty water
will not even bother the alagators or fishes in the sewers.

disclaimer: this is not a engineered or recomended solution. this is
a post in a news group, and for entertainment only. if you plan on
protecting your health, research your materials and potential
hazzards and risks involved and act accordingly.


Dave

--- In CAD_CAM_EDM_DRO@y..., "ballendo" <ballendo@y...> wrote:
> Jon,
>
> On this list, we do not know if someone asking a question is
planning
> to do "only a few a year" or if he or she may be planning to use
cnc
> to set up a production line... Certainly both types have visited
here
> in the past, and will likely do so again...
>
> Second, PCB dust may have been the focus of the thread, but the
> advice here to think of your neigbors, and their children, is
simply
> an overall good idea...
>
> Finally, I do not know anything about your home and its
relationship
> to your neighbors, even though you post regularly. Maybe you have
> lots of room. And possibly live in a rural area. Please keep in
mind
> that others may be in a city core; in an apartment or other sort of
> shared living arrangement. This may make their need of concern for
> the neigbors greater than your own...
>
> Hope this helps,
>
> Ballendo
>
>
> --- In CAD_CAM_EDM_DRO@y..., Jon Elson <elson@p...> wrote:
> > Raymond Heckert wrote:
> >
> > > At least, think of your neighbors. The dust may ruin clothing,
> food, or do
> > > damage to the seven-layer paint job he just put on his car, not
> to mention
> > > the safety of the neighborhood kiddies. Don't forget, we're
not
> just
> > > talking about dust from phenolic or fiber-glass boards; You're
> generating
> > > thousands, perhaps millions of tiny copper slivvers, too!
Please
> don't give
> > > HSM's a bad reputation by disregarding safety for the sake of
> others. If
> > > you can't do it right, then don't do it at all.
> >
> > Oh, for gosh sakes! I think you are overreacting! This is not a
> horrible,
> > persistent, noxious invisible poison that will be tracked around
> the neighborhood
> > untill the EPA arrives in the moon suits.
> >
> > If I did PC board milling, drilling and routing on a daily basis,
I
> would take
> > dust control measures much more seriously. But, I only do a few
a
> year,
> > and then clean up with a shop vac. It does make a white, fluffy
> mess on
> > the machine table, and you can just detect a hint of it on the
> floor, but
> > it doesn't fill the house with dust, or get into every pore in
the
> place, and
> > slowly sneak back out months later. It is NOT going to destroy
the
> > finish on your neighbor's car, unless you are doing it in HIS
> garage,
> > next to the car!
> >
> > Jon