 Steve Cater (http://www3.sympatico.ca/caters/Wood/Cyclone.htm)
alerted me to the fact that these cartridge filters we use are designed
to be used from the outside to the inside. Most manufacturers go from
the inside out since it’s easier and less space-consuming. The
reason that it’s better to go from the outside-in, as I understand
it, is that you maximize the surface area of the pleats of the filter,
which will result in better air flow, and less resistance from the filter.
From Bill’s page I see that another way to go about this is to
use two filters going from the inside out, which creates enough surface
area.
I didn’t want
to have two filters, and at $56 from buy-filters.com, one was enough
for me. I built the filter housing based off Steve Cater’s, with
one minor difference. His was designed so the output from the blower
was directed right at the pleats of the filter, because the pipe entered
from the side. I was worried about this causing damage and causing a
build up of dust on that side of the filter. As well, I didn’t
want to take up as much floor space as this set-up would necessitate.
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Cartridge
filter mounted horizontally in a sealed MDF housing |
This mix of design
requirements worked out well, and as the pictures show, I mounted the
filter horizontally in a box that has holes on either end. So, the incoming
air and fine dust from the blower hit the metal plate that’s at
the bottom of the filter (now the right END of the filter) – it
acts as a buffer.
 |
After
flowing through the pleats of the filter, clean air is exhausted
back into the shop through this outlet |
The fine dust is captured in the pleats, and the air is expelled back
into the shop out the hole in the other end. This works out well since
I am building an air cleaner from an old squirrel cage fan I have from
a replaced furnace. I will mount this on the opposite side of the shop,
and, when both the dust collector and the air cleaner are on, it will
create a nice circulation of air throughout the shop space resulting
in better filtering and a safer environment.
 |
All
joints sealed with silicone. Note foam seal for detachable left
end and plastic viewer. |
A few notes on the
design. All the joints where MDF meets MDF are sealed with silicone.
Remember, I was taking extra pains to make sure that the cyclone, blower,
and filter housing were hermetically sealed. The left end of the housing,
as well as the plastic viewer in front, are detachable. I used the same
½” x 3/8” foam strip material to seal these joints.
The reason the end is detachable is quite simple: it is the end that
the filter is connected to via a ½” threaded rod and wing
nut, and if the filter ever needs to be replaced or otherwise adjusted,
that end will have to be removed. The plastic viewer is designed to
see the condition of the filter. It also acts as a clean-out to clean
the filter and any stray shavings or chippings that aren’t separated
and find their way into the filter housing. Thus far, not a single one
has, so I don’t anticipate using this too much. When the time
comes to clean the filter, I plan to blast the thing with compressed
air from the inside out by sticking a pipe with several holes along
its length into the left end of the filter. This should put a nice caking
of fine dust throughout the housing. In that event, I might remove the
plastic to vac all that out. However, it occurs to me that it might
be much easier to merely detach the flex hose from the right end of
the housing, and stick my vacuum in that way. We’ll see.
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Housing
mounted with hinges for easy removal of filter |
Finally, the housing
is mounted with hinges to the floor joists above. This is the case because
the left end butts right up to my scrap rack. If I ever wanted to pull
the filter out from the left end, I would need to bring the housing
away from the wall. The hinges allow the housing to move away from the
wall without detaching it.
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