This is my homemade workshop air cleaner,
which is based on one of these four inch thick
forced air furnace filters, but those filters now cost about
$35.00, so I thought I'd try to make one
out a forced air furnace hammock filter,
which only costs $11.00, and it's almost the same area,
and it seems to be very similar material.
This filter has, a sort of, wire mesh to hold the filter
material in place so I'll try to make that out of chicken wire.
From experience, I know that folding a wire mesh
is pretty difficult, so I set up, a sort of a jig
between two workbenches.
I have nails that go through holes here to line up the boards
and I'm using alternate thick and thin layers,
because I want the pleats to be thin on the one side,
and thick on the other side. Now, with two folds made,
I need to start recycling the boards from the bottom.
The shorter the end that I'm folding is, the easier it gets.
I didn't want to have to deal with too long a tail to keep
flipping back and forth, which is why I started in the middle.
So, after having worked to one end, I went back to the middle
and started with the other end.
Well, that whole folding thing was not as elegant
as I was hoping, but I think I have something
that might be useful, I think I'll be able to
force the filter material
on to this. Now I need a box for it,
and for that I glued together some silver maple boards.
These actually came from my own sawmill.
OK, pieces are glued, jointered and planed.
Some of it actually came out quite nice.
Now it's time to make box joints.
The sled was starting to get hard to push, but a few
drops of oil in the slots and on the table, really makes it
slide easy.
All right, got the box joints cut.
Box glued together, and the chicken wire crammed in there,
but it's not exactly regular spacing,
so I need some kind of comb to support this.
I got 60.4 centimeters in a box, I need ten and a half folds,
which means I got 5.75 centimeters per fold.
So, I just worked it out on a calculator, 5.75,
you know, this one I can just use constant calculations
so plus equals, it tells me next one is 11 and a half,
and I just keep pushing equal, and that works out
the intervals that I've marked on here already.
The second comb I cut, I drilled the holes for where I need to
turn on with the bandsaw blade, which sped things up a lot.
Now, I just got to be able to jam that chicken wire onto
those combs. Oops.
Backwards.
Well, it's not as straight as I hoped, and the chicken wires
breaking a few places so supports in the middle really help.
Got the chicken wire all mounted, and I screwed it down
in a few places to hold it down, and there's quite a few places
where it just, kind of, broke so if you try this,
use new chicken wire, not rusty brittle old stuff.
Another way to support the filter material,
will be just to have a bunch of sticks
and then have the filter go in between those
like that, the problem with that
is as the air pushes in here, this is gonna
be inclined to go more like this, it'll just, kind of,
pinch together right here, and then this whole area
becomes useless, so what I could end up, is basically
just something like this.
So, what I'd have to do is, not just have sticks to hold it
on the edges, but also a few sticks here,
to support that filter material, and at that point it gets
very complicated, and if I did it this way,
I'd probably say, "This is so much work, I should have just
used chicken wire." The filter material is a fair bit
wider than my chicken wire, so I'm using my table saw
as a guide to cut it down to width, I figure I might as well
sew those scraps back on the end.
The filter is actually three times the area of the box
except I ran out in this corner, and I had to use
some blue shop towel. I need some sort of fan
to pull the air through my filter, and for that I figure
I'll cannibalize this oscillating fan
I need it to be very shallow this way, so I'll
have to shorten that shaft, and mount the blade
a little closer, I'm gonna take the gear box off the back
and use those mounting holes.
Unfortunately the wire goes through these plastic parts
and I'd really rather not cut the wire.
Now, I just have to grind a new groove in there
for a snap ring.
I ground a flat spot on here, and shortened that shaft
some more, and I also ended up widening that ring slot,
so that when I put the fan blade on here,
I can lock it on with a ring like this, because I lost
the screw thread that I had.
Now, I need to mount this fan motor in here,
and I'll make some kind of bracket out of
a piece of plywood for that.
I'm drilling a few extra holes to allow for air flow
to cool the motor.
Now, I still need to make sure that all the air that this fan
pulls, comes through the filter, and not just
circulating through here, so I need to put a baffle in here
and I've already glued some rails in place to hold it.
And, I'm gonna make it out of this, which came from
the back of a piece of discarded furniture.
I glued some blocks of wood on the back to give
more hold to the screws.
This air cleaner has started to look quite nice,
so I figure it was worth a coat of green paint.
So, now let's try this thing out, I've got a fan
to circulate air all around the shop
and I'm gonna deliberately make a lot of air-borne dust
by grinding up some MDF on the belt sander.
Gross. So, I think I have the dust
evenly spread now, so these are the readings,
and I'll just let that run for about 20 minutes
and see how it decays. So, this is a bit over
20 minutes later. So, this larger air cleaner
is able to cut the air-borne dust levels in my shop in half
every three to four minutes, whereas my older
air cleaner, takes about seven or eight minutes to do
the same thing, so this has probably got much
higher CFM, I'd guess probably about 450 to 500.
And, this is what the old filter looks like, right now.
It looks really, really dirty.
But, having just tested it, it still works almost as good as
new, it just doesn't get the particle count quite as low as
it used to. I built it four years ago,
and I made a video about it, of course.
And, here's what I actually made it for.
It's to blow air over the wood stove,
and clean the air in my big shop at the same time.