rotary switch for DIY air filtration?

[Zane Harris]

Any idea where I can get a 4 position rotary switch (on the cheap) to select the speeds on a DIY air filtration unit. The cannibalized squirrel cage fan I've got has 4 power leads, each providing a different speed. TIA

[Jeff Erbele]

Any idea where I can get a 4 position rotary switch (on the cheap) to select the speeds on a DIY air filtration unit. The cannibalized squirrel cage fan I've got has 4 power leads, each providing a different speed. TIA

Grainger, Gray Bar, and McMaster Carr come to mind first, or any electrical supply house.

Add "on the cheap", well I don't know that one is super expensive in the first place, but I would look to the surplus stores and salvage companies.
Or cannibalize a switch from another source, say a cooling fan / box fan from a yard sale. The problem with those are most are 2 or 3 position.

On the other hand I wonder why you need to use all of the speeds. I would think you would want to run it on one speed, perhaps the highest all the time.
I would wire it direct, plug it in and try it to find out; select the best speed, wire nut and tape the remaining wires out of the way and use a common on/off, two pole light switch. But maybe I am lacking something, your needs, your intent, etc.

[Alan Schaffter]

I used an inexpensive 4 position/3 speed pull chain fan switch on my air cleaner when the receiver unit went out. They cost about $3 at most big box and hardware stores. I also prewired my ceiling with a switched outlet. Instead of a wall switch I use a timer.

[Sam Puhalovich]

When I built my ceiling-mounted, squirrel-cage, 3 speed air-cleaner ... I bought a 3 position switch at a electrical supply house (about $25).
I installed the switch and got the expected results ... 3 speeds. I expected to run the fan constantly on 'low' ... switch to 'high' as needed.
However; when I installed the filters ... all I got was 'high'.
I've not been able to figure-out why.
I'm with Jeff ... try wiring for a single speed first.

[Zane Harris]

Okay, going to try a simple SPDT switch, on-off-on, to use two speeds first. I'll install a terminal strip inside the enclosure so that I can experiment with which two of the four speeds I want to use.

Next issue, inside the enclosure, how much clearance should I provide to each side of the squirrel cage to allow adequate incoming airflow? The outlet of the cage is 10" x 9.25", and the diameter of the side openings into the cage 10" each side. 1/2 HP motor, maximum speed 1050 RPM.

[Sam Puhalovich]

The terminal strip is a good idea.
The squirrel-cage that I have is the same size ... I used 6" per side for clearance.
It's working very well.