On 04 Mar 2006, John Rumm wrote:

To be fair, I think we are dealing with two different problems
he

At the simplest level of just catching the heavy dirty dust
generated when drilling brick or blockwork, then the envelope
will deal with most of the *visible* dust that would otherwise
fall on your carpet, and hence can in many cases be declared
adequate.

However when you start trying to catch *all* of the dust
produced, including the very fine particulate dust that is
emitted into the *air* from the drilling site (and later settles
out all over the place), then you are into a whole new ball
game.


John, I think you're one of the few people in this thread to
appreciate that this ultra fine dust is exactly what I, as OP, am
having problems with.


Even with vacuum collection some of this sub micron stuff
will be sucked straight through any filters and returned to the
air again. In these cases, containing the dust at the production
site is going to be more effective. This is obviously important
where the fine dust can not be tolerated either due to its
harmful nature, or its ability to contaminate.


From all the suggestions I find that the best way (and it's not
great) is where I use a small square of filter-bag material in
between the hose and attachment of a domestic vaccuum cleaner.

All the dust gets drawn in including the fine stuff. The really and
truly fine stuff passes thru the filter material (as a second square
will show) but *hopefully* it gets trapped by the actual dust in the
main vaccuum cleaner bag or by walls of the main bag.

What's left topass thru the bag and then thru the vaccuum's exhaust
filter isn't worth worrying about. The main issue here may be how
fast the main bag gets clogged to the point of being useless.

I guess a Dyson-style vaccuum centrifugal cleaner + HEPA filters
would be better at trapping the dust. (Is this correct?) ANd I was
asking in another group if an el-cheapo £30 Bush DD2227B bagless
Cylinder Bagless from Tesco is any good as I could devote it to this
task. See http://snipurl.com/n6h1

"The Bush DD2227B Cylinder Bagless is a 1200W
cyclonic cylinder cleaner. High level of
filtration. 1.5 litre dust capacity."