Help again on Craftsman radial arm saw

kelLOGg

Bob
Senior User
The saw can be seen in an earlier post:

Currently, when I turn it on it will do one of the following:
1. make no sound at all and the blade/motor doesn't turn.
2. hum/vibrate and blade will turn very slowly.
3. run perfectly

As of this writing #3 is its current state. I took the electrical cover off to make measurements and upon turning the saw on I once heard a verrry faint click possibly coming from the relay but usually I don't hear it. Maybe a failing relay? The start capacitor holds a charge that slowly decreases when I measure it with a voltmeter so I think it is OK. The relay is a Klixon ACR-1-735 and no longer available. It measures 1" x 1.25" x 2" (see pic) and I can find one that looks just like it in a meat cutting machine (for $40+) but no specs are given and I don't know what the specs (amps) are on my relay. I'm reluctant to buy it knowing nothing about it but its appearance. Any ideas? suggestions? extra relay?:)
 

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patlaw

Mike
Corporate Member
Assuming the saw is 120v, I suspect the relay is 120v and is switching 120v. The objective may be to not use the switch for higher current necessary to run the saw, but I'm guessing. What's the model number of your saw? An obsolete relay can be replaced with many alternatives, so long as you have the space. You could (probably) bypass the relay and used a foot switch. Use your volt meter to check the voltage on the coil when the relay activated.

I can't tell from the picture, but if the relay is open frame, the next time the saw doesn't start, take something the doesn't conduct electricity and push on the contacts. If the connection is bad, the additional pressure can cause the contacts to make, and the motor will start running.

Someone here may be familiar with that saw and have a better idea.
 
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kelLOGg

Bob
Senior User
Model # is 113.29460. I have reset the push pin connectors on the relay several times to assure they make electrical contact.

I'm not sure what this relay does. There is a neutral wire connected to one terminal and the other two terminals have wires that go into the body of the motor presumably to windings. Maybe it performs the function similar to that of a centrifugal switch to switch from a starter winding to a run winding but I don't know how it knows when to switch. That may explain its expense of $40+.
 

patlaw

Mike
Corporate Member
A centrifugal switch is activated by the rotation of the motor. From your picture, I don't see any way for this relay to operate except electrically. Since it's working, watch the relay while you turn on the saw. If it follows the motor, it's a run relay. If it drops out, it's bizarre. A run relay would only need three wires -- neutral and hot for the relay coil (from the on-off switch), and one wire for the motor. Use your volt meter to measure the voltages on the terminals when the saw is stopped and when it is running. Since I haven't seen this saw, I'm just guessing trying to help. I'm surprised someone who knows what he's talking about hasn't chimed in yet.
 

junquecol

Bruce
User
It's called a potential relay. The heavy in rush of current upon start pulls it in and engages the start windings. One wire goes to run windings and other goes to start windings. Grainger stocks them, along with most HVAC parts houses.
 

kelLOGg

Bob
Senior User
I didn't know about that type of relay but it make sense. All I need to know is the current required and find one that fits dimensionally,. Thanks.
 

junquecol

Bruce
User
Before rushing out to buy one, I would shoot some contact cleaner into the old one. If you can't find contact cleaner, brake cleaner will work. Could have some trash in there.
 

patlaw

Mike
Corporate Member
Bruce, correct me if I'm wrong, but there's nothing special about the relay. It's a coil of wire that generates a magnetic field to pull in an armature that closes the contacts. The difference is how it's wired in the motor circuit. Does the relay drop out after the motor is up to speed?
 

kelLOGg

Bob
Senior User
Bruce,
The screwhead and nut shown in the pic are tightly sealed presumably to prevent tampering as well as holding the part together. It's hard to see how dust could get inside.
 

kelLOGg

Bob
Senior User
Yesterday brought good news. Michael Matthews came to my shop and removed the relay. The screw holding it together had sealant to keep it from vibrating loose during use so it required some careful determination which Michael executed confidently. Once inside it was like brain surgery with all the small parts, springs, contacts, etc., requiring delicate handling. I and my friend who actually owns the saw and keeps it in my shop played OR nurses assisting and handing Michael tools for parts removal. He got the contacts out and they were really pitted and worn. Michael sanded them clean, reassembled the relay, turned the power on and VOILA!, motor running. Now I am sure it will run for many years. Thanks to Michael!
 
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