Pure As The Driven Snow

Have you ever experienced pristine driven snow on a mountain top?  I have.  The snow may be pure, but it is generally uncomfortable to see it.  But this post is not about mountain sojourns and existential reflection.

I have an air cleaner in the outside shop that was built about two years ago.  It ain't pretty, but it keeps the dust down.

Pragmatic Air cleaner

This build is the epitome of pragmatic woodworking.  Everything is reused from other sources.

The genesis of the air cleaner was a new furnace in the house.  With something like this project in mind, I told the installers to leave the motor from the old unit.

The motor then sat around for several months until I was making some picnic tables out of treated wood.  The machinery kicked up what I consider a toxic cloud of treated wood dust.  I often say that laziness is the mother of invention, however in this case, necessity truly was the motivation behind this build; nobody wants to breathe that stuff in.

The first design plan consisted of 'fit the box around the motor'.  The more considered design is based around the filters from the new furnace.  Buying the HEPA filters for the house, and reusing them in the garage is a very sensible plan--proven by the test of time.  The filter size is 16X20X1 and the resulting plywood box is 21 5/8 deep, 17 3/4 high. and 16 1/4 wide.  As you can see in this photo, the joints are simply glue, screw, and 'somewhat close' dimensions.

Finely Crafted Joints

I won't go into detail about building the box itself; if you need that level of detail then you are worse off than me and should start with Golden Books Introduction To Wood.  Just kidding.  The box really is nothing special.  I started with four sides cut to dimension: front, back, top, and bottom.  I bought six Craftsmen corner clamps from yard sales over the years and they once again proved quite valuable in aligning and assembling these four panels.  The sides were left off to dry fit the motor before final assembly.  Cut outs for the motor and the two filter sides were labeled right on the surface and cut with a jigsaw.  Roughly.  But not so rough that the area around the motor could not be sealed with silicon.  After all, the only air you want is what the filter lets in.

The motor is wired for a two stage control.  In haste, I skipped the fancy wiring (read 'didn't want to spend the money') and direct wired it using a found electrical box and a single pole 15 amp  light switch.  Did you know that you can score and crack an outlet faceplate just like a sheet of drywall or glass?  Well, you can, as you can see below.  I digress (don't you hate it when authors hide a snarky sidebar with the words "I digress"?), the electrical cord is a standard computer type with the house shaped end snipped off.

Stunning Presentation

The clips used to hold the filters in place are 1/2" conduit holders found at the bottom of my electrical toolbox.  They are screwed down  by hand for a friction fit.  All the clips have to do is keep the filter from falling out when the unit is powered off.

This air filter works so well that I often use it like a dust collector.  That is, "on" when the tools start and "off" soon after using the tool.

For two years the air in the outside shop has been as pure as the driven snow due to a couple hour build dictated by necessity.

Gory Details