In this video, I'm gonna make an air cleaner
using this motor, and this 20 by 20 inch furnace filter.
A few years ago, I experimented with
how to mount this motor from an oscillating fan
onto a piece of wood, without actually modifying it.
So, I took the shaft that it normally oscillates on,
and I cut a thread into here, so I can put a nut on it,
and that pulls it onto a piece of wood that fits
onto the motor's housing. This blade is quite a ways
from the motor, so I want to bring this back here.
The shaft is only press-fit into the rotor,
which means I should be able to just pound it through
to make this end shorter.
I just ground the end smooth here, but I also noticed
there is some ridges on here, which is to give this part
more grip, because that used to be right there, so I'll have to
polish those out.
Well, those ridges are still visible, but it feels really
smooth the the touch.
Now, sometimes after reassembling the shaft
on these motors is hard to turn because things are
suddenly out of alignment, and the way to fix that
is to just whack it a bit
and that will get the self-aligning bearings
closer to alignment. With the fan on top of the
filter, this tells me how thick an enclosure
I will need, and I think 15 centimeters should be enough.
And, for a change, I'm actually gonna use some
new plywood for this. I cut the first piece
off the end, because I don't need these pieces to
have to be that long, and this way my remaining scrap
is a much more useful size. Now, I need to join
the pieces in the corners to form a box,
and for that, I'll just use box joints, of course.
I was aiming for a very snug fit with the filter
but what I ended up with, is an interference fit.
So, to make it easier to jam the filter in there,
I'm adding a chamfer to the inside edges.
These pieces of wood will limit how far the filter can be
pushed into the frame.
The sides of this box had a tendency to bow inwards
a little bit, so to make them bow outwards
while the glue dried, I jammed these pieces in there.
But, that has another problem, because that actually
forced my box, a little bit, out of square.
Actually, it turns out all the corners are a little bit large,
and that's because the sides are bowed outwards a little bit now.
So, that's actually good. Means that filter should be
not that difficult to get in.
Yeah, yeah. That's not bad.
I'm having to extend my motor mount piece, cause it's
not quite long enough to reach across the box.
While I'm waiting for the glue to dry, I'll figure how to
mount this, and these buttons should all nicely fit
inside of a half inch slot.
These two wooden blocks allow me to mount the buttons flush
with the outside of the case.
A problem with this motor is that even at full speed
it doesn't run very fast. But, if I put a half a
microfarad capacitor in parallel with this run capacitor,
that speeds it up a fair bit.
And, that tells me this capacitor isn't as good as
it used to be. So, I cut the old capacitor off
and put this one on here, which is actually a 3-microfarad
instead of 2-microfarad, but it's close enough,
and it runs much better now.
So, I'll just solder those connections and leave that
one on there.
Now there is a question of how far back should I
place the baffle, in terms of this way or that way.
And, I always figured it was best to put it a little bit
behind the fan, because centrifugal force
is gonna throw some of the air out, like this, right?
But, checking the fan, it turns out it's not like that at all.
And, you can see it's being blown this way.
But, as I get to the edge of the blade,
you can see it's actually not moving forward at all,
and if I get to here, it's being sucked in towards the blade.
So, I think what's happening is we have an awful lot of air
being blown here, and we have a little bit of resistance
from the filter, back here, and it's enclosed,
and so air is being sucked in, actually, from the sides.
And, that means I'm just recirculating some of the air
from the front, which means I should really move those
baffles forward of the fan blade.
I am still getting some air sucked in, right next to
the fan blade, but at least I'm getting any sucked in
from the side. Of course, what you can also do,
is just buy a box fan, and strap a furnace filter
to the back of it, and that works just fine,
but with a box fan, you never have this baffle around
the blade, like this, and that means if there's any resistance
from the furnace filter, a lot of the air that's being
blown out here, actually comes from the front and loops around.
So, I think this is a much more elegant solution.
I glued a ledge into the box to have something to screw
the front panel onto.
I've been making lots of dust on the belt sander
and measuring how fast this one clears the air,
with my DYLOS dust meter, and it works about as well
as the one I've got up here, so between the two of them,
I should be able to clear the air twice as fast.
1 I made these two mounts, and together with some
pieces of inner tube,
that will suspend it, and vibration isolate it.
And, this just mounts to the ceiling.
And, this here is the designated chaos area of my shop,
which is why I almost never show this part in a video.