Projects:Table Saw Automatic Dust Collection

Table saws are messy, and they need dust collection. The problem is remembering to turn it on. There are various solutions out there on the web to automate your dust collector, but not too many specifically for using a 120V dust collector with a 220V saw. That is the goal of this project.

It turns out there are tons of components out there for switching and sensing, and there happened to be just the right combination to make a pretty simple setup for this.

Parts:

• Dwyer Miniature Current Switch, MCS-111050, Solid Core, .5 to 50 A Continuous - $27.40
• Packard C230B 2 Pole 30 Amp Contactor, 120 Voltage Coil - $10.79
• 16ga Wire, approximately 4 feet - $4
• 220V plug - $7
• 220V outlet - $6
• 120V plug - $4
• 120V outlet - $4
• Enclosure - $15
• Screws
• 2" Conduit clamps for mounting - $8

The Contactor is essentially a big relay. It takes a small voltage on one pair of terminals, this powers an electromagnet that draws a metal plate down, and that metal plate connects two other sets of terminals carrying much more power. In this case, this Contactor uses 120V at around .04 Amps to trigger the coil, and the main load can carry 120V up to 30 Amps.

The Miniature Current Switch, or Current Sensor as I'll call it, is also a relay but more special. Instead of connecting power to it by a pair of terminals, it receives power through induction. With a wire running through the hole in it, when that wire carries a lot of Amps it will induce a magnetic field inside the Current Sensor. This magnetic field is then turned back into a small amount of Amps that turns on a relay.

So using the Current Switch, we can sense the table saw is drawing a lot of power (when the motor turns on) and make a connection to something else. That something else the Contactor, which we will connect our Dust Collector to.

The Wiring:

• show diagram
• The 220V is essentially just passed through the box, except one of the power lines goes through the hole in the Current Sensor.
• The 120V gets connected to a few places. The Hot line goes to one side of the relay on the Current Sensor and of the Contactor. The Neutral line goes to the outlet,

Other/Similar solutions found online:

• Thread on Sawmillcreek.org about auto-switching dust collectors
• Thread on Lumberjocks.com
• iVac auto switch (for 120v)
• Matthias Wandel - Relay box for dust collector
• Eagle America - Remote Switch
• Eagle America - Multi-gate Switch System