Introduction: Build an Automatic Shop Vac/ Power Saw Switch

About: When I was a boy, I was amazed how my grandfather could make flotsam and jetsam into useful things. I am proud that I have inherited some of his skill.

In a first class woodworking shop, the craftsman merely pulls the trigger on his power tool and the dust collection system turns on, too, thanks to a device called a current sensing switch.

OK, so my shop is just a tad less than first class, but I still needed to do something about sawdust.

Step 1: The Way It Was...

In order to keep the depth of sawdust on my tools to a minimum, I have repeatedly tried to use my shop vac to suck up dust from my stationary tools. The biggest problem with this idea was that I needed my shop vac for a lot of things so my miter saw usually just blew sawdust into the air.

I had often thought of using an old Electro Lux vacuum as a dedicated dust collector but I never got around to it because the end of the suction hose was much smaller than the saw output.

Eventually, I pulled the vacuum down from the attic and began connecting various hoses and PVC fittings into something that connected my vacuum to the mitre saw. This consisted of a 6 foot hose section from an automatic pool cleaner, 2 45 degree couplings, a short piece of PVC pipe, and some electrical tape.

Once I got the vacuum plumbed to the saw, I still had a slight problem: I had to turn it on and off. Very often, I just use the saw for one or two quick cuts. So why bother to turn on the vac? Easy for me to say, until the dust on everything gets annoying. So I decided to do something.

Step 2: Automatic?

On a scale of costs tools and accessories, a little over $30 for a current sensing switch to turn my vac on and off when I used the saw is cheap enough. Except I would rather spend twice as much money and 4 times as long to make something that works something like the original than buy it.

It wasn't hard to decide on leaving the vacuum switch in the on position and using another switch to turn on the power to both tools at the same time.

Switch off, everything off. Switch on, pull trigger, both on. Simple but I confess only automatic in the sense that when the switch is turned on, current automatically flows.

Still, it works pretty well.

Step 3: How to Do It...

1 - 115 volt receptacle
1 - SPST switch
1 - square wiring box
1 - cover for " with cutouts for
receptacle and switch

Length of flexible electrical cable to suit, 2 conductor with ground, capable of handling saw and vac load
Plug for cable
Screws, wall anchors, etc..


The short extension cord will plug into a nearby receptacle. IMPORTANT: It must have a current handling ability sufficient for your tool so check on that first.

The wiring will be routed as follows: white wire to bright screw on receptical, green wire to ground screw on switch, then to ground screw on receptical, black wire to one screw on switch and from second screw to brass colored screw on receptical.

Mount the completed switch near your power tool and plug in your vac and tool. Turn on your vac switch. Your saw won't run (a safety feature, too) until the switch is on, and then the vac comes on, too. Automatically.

This is a simple project for anyone with a modicum of electrical experience. Safety wise, never fail to observe all safety guidelines; do everything you should and nothing you shouldn't.