On Thu, 24 Sep 2009 11:59:05 +0000 (UTC),
(Andrew Gabriel) wrote:

As you've discovered, a bagged cleaner is useless for the volume
and rate of dust generated by a wall chaser. You have to use
something which keeps the collected dust out of the air path.

Having done some more chasing since my last post, I am revising my
opinion slightly. I notice that the dust that was escaping was being
ejected through a small slot on the back on the chaser. The base plate
pivots so that you can adjust the depth of cut and dust was escaping
from the small gap above the joint. I placed a bit of tape across it,
once the depth was set and that contained the dust.

Some dust also leaks from the outlet. I guess the plastic tube is not
a perfect fit. Perhaps I should wrap the joint in amalgamating tape?

I knocked the tube off accidentally and there was a LOT of dust, so I
think the vacuum is doing a really good job. That said, I wonder
whether the design of the chaser is also to thank? It seems very
effective at directing all the dust towards to outlet. I wonder
whether if the pipe was connected to the vacuum but the vacuum was
switched off, how much would still be thrown down the pipe into the
vacuum by the chaser?

I'm not brave enough to find out but I'm sure I did this a few months
ago when my vacuum was broke. I also remember sticking the hose out of
the window, when I was near a window!

I've used a DC04 and DC07. Both work well. The DC07 is a more
recent and powerful model

If I do find a bargain on ebay I may get one to try. Is the difference
between the 07 and 04 that noticeable?

If you're stuck with a bagged cleaner, interposing a cyclone
before the bag will help. Constructing a cyclone which really
separates out the finest dust isn't easy and it's this that
either cloggs or passes right through the bag, although the
type of dust (heavy) involved here is the best for cyclonic
separation.

I looked at the pre filters on the URL given earlier in this thread
but they were great big things. That's fine when they are for
stationary use in a workshop, as those were, but for moving around a
room, I think they might be too bulky and something else to trip over.

Thanks again.