ARTICLES & REVIEWS

Homemade Cyclone Dust Collection System

Part 7: Electrical Work

by Steve Silca

This area deserves a brief write-up. The motor is 220V. I ran 10/3 flexible conduit from the circuit box, through a double pole switch, and then to the motor. I was fortunate to have a spool of this stuff from a previous electrical project. Otherwise, it is probably $50 in wiring. In the circuit box, which I am fortunate to have right in the shop, I used a double pole 20A breaker. I think I could get away with a 15A double pole breaker, but I elected to use a 20A. This proved a good idea, because I ended up having a couple other items operating off these breakers. I added a low voltage switching system and a fan to cool the motor, both of which were powered with the dust collection circuit.
I was not satisfied with having just one switch to turn the collector on, so I replaced it. I purchased a DPST (Double Pole Single Throw) relay from McMaster-Carr for $12, which operates with 24 VAC input. Essentially, this is a double pole switch actuated by the completion of a 24 VAC circuit. So, I wired right into one of the hot wires of the dust collector circuit a 120VAC to 24VAC transformer. These are available for about $12 from a hardware store (your doorbell probably operates with one of these). The reason you transform this circuit to low voltage is because then you can just run wires without having to worry about conduit or electrical boxes and connectors. I then located six total switches in convenient locations around the shop – two 3-way switches, and four 4-way switches. I used about 100 ft. of 18/3 thermostat wire to wire all these switches together so that the dust collector can be turned on or off from anywhere in the shop.
I chose this system for two reasons. The first was its cost effectiveness. I was able to procure the switches and switch plates for free – so this set-up only cost me $34 for the relay, the transformer, and the thermostat wire. I didn’t want to spend money on a fancy remote system, and didn’t think it would fit my needs. Secondly, I didn’t want to put a switch on every blast gate as some have done. This would mean that every blast gate has to be closed to shut the system down, and sometimes I don’t want to have to do that. As well, if I’m moving from tool to tool, I would have to go open the second tool’s blast gate, then close the first tool’s blast gate, just so the motor doesn’t turn off and back on. Not only is this inefficient because of the extra time it takes, it is also a waste of electricity (it takes a lot of juice to start a motor over and over again) and is extremely bad for the motor. I am no expert with electricity or motors, but I have read that more than 6-10 starts in an hour is horrible for a motor. It has to do with the capacitors getting too hot, or so I understand. As well, you can just tell intuitively when you turn this baby on that the starting phase of the motor is the most painful thing for it.

One of six switches located around the shop

Anyway, my system of 3 and 4-way switches meets my needs best, reduces the number of times that the motor gets turned on and off, and I think gives me more flexibility. The switches are located over the miter saw, over the radial arm saw, amidst the band saw/belt sander/drill press cluster, in between the sanding center and the surface planer, above the jointer, and above the table saw. Basically, they’re located around the perimeter of the room and one in the middle of the room.
The second item that was added to the dust collector circuit, and made me glad I used 20A circuit breakers, was a fan to cool the motor. The motor I used is a compressor duty motor, and is not designed to be mounted up against the motor mounting board as it was. They are designed to have air flowing through them to cool them as they operate. My set-up made it very difficult for air to flow through this motor. Not only was it mounted up against a board (it’s actually about 3/16” above the surface of the motor mounting board because it rests on four small bolt heads that hold the motor case together, so there’s space for a tiny bit of air flow), but it was mounted up high in the corner of the shop where little air flow can get to it. To complicate things, since heat rises, any heat that the motor creates stays right there in that corner. I effectively created a self-heating oven for my motor.

Fan to cool motor


Now, this oven takes a little while to develop - about 25-30 minutes. I noticed it for the first time when I had the collector on for about an hour, and then it wouldn’t turn back on because its own internal thermal protection system wouldn’t allow it. I’m actually surprised it didn’t just shut itself down, which is what I think these thermal protection switches are supposed to do, but I’m not sure. In any event, I wired a fan to turn on when the dust collector does. This fan is aimed right at the motor and hopefully accomplishes two things. One, it gets more air flowing through the motor to cool it. Two, it brings cool air to that upper corner and pushes some of the hot air that may develop out away from the motor. It does not keep the motor cool, but it does keep it from getting so hot that it burns up. In the future, I might put up a fan that can move a larger volume of air to see if it cools the motor more effectively. As well, in warm weather, I can open the window behind the dust collector and really create a good ventilation system through and around the motor.

 

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© 2003 by Steve Silca . All rights reserved.
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