as part of the "new shop" I scored an oneida 3HP commercial dust
collector (VROOOM - drive by #1)... The problem is, the shop is 40X50 feet
(thats number 2), and its a real drag walking all the way over to the DC
every time I need to turn it on or off.
Here's my solutution:
1) relay of the right size for your DC (Get one rated for low
voltage DC for the coil size - I'm using 24VDC)
2) one transformer to provide the DC current
3) one "micro switch" for each of your blasst gates (there should be
a blast gate at each tool) The micro switch is just a small switch with a
long spring loaded arm. When the arm is pushed, the switch closes.
4) enough thermostat wire to run from the DC to all of your blast
set up the transformer, and wire your DC power supply through the relay.
hook one of the legs of the transformer to one of the legs of the relay
coil, and the other to the red side of the thermostat wire. Hook the white
side of the thermostat wire to the other leg of the relay coil. run the
thermostat wire to the closest blast gate. Leave a couple feet of wire, and
run another length to the next blast gate. Continue until you've got a wire
going to all of the blast gates.
Now you need some way to mount the switch to the blast gate. First of
all, figure out the best way to mount it to make it work. it should be set
up so that when the gate is opened, it pushes on the switch arm, and closes
the switch. If you've got plastic blast gates, you can drill holes to mount
the switch (be carefull not to do something that prevents the gate from
opening...). If you've got metal gates, you can drill them as well, or if
you've got metal gates that can be disasembled, you can use the bolts that
hold them together as mount points (this is what I did).
I made brackets to hold the switches out of cheap hardware store bar
stock metal (I think it was 1/2 by 1/8). Cut it to length (in my case about
3"), and drill holes to match the mounting holes in the switches and
whatever method you're going o use to hold the switch to the blast gate. Go
bolt all the switches to the blast gates, and make sure that the gate closes
the switch when the gate is open (a continuity tester is usefull here).
attach the wires to the switches, testing each one as you complete it.
If its working right, every tim eyou open a blast gate, the DC will turn on.
When you close the blast gate the DC turns off.
My total system (10 gates) cost about $50 US, and took about 3 hours to