Craftsman Table saw Start relay Question

[sawnuts]

    Hello all,

I have restored a number of old (40's through the 60's) in the last few years. This past weekend I see someone was giving away a early 90's Direct Drive 10" saw near me.

I didn't have anything going in the shop so I drove the 4 mile round trip and picked it up.

I was not able to hear the saw run before picking it up so I was very interested in how it ran once I got it home.
I had it flipped upside down on a work cart and when I turned it on it did not sound happy.

I figured I better check out what was going on with the motor because if that is bad the entire unit either needs to be scrapped out or parted out.

After snooping around I had more questions than answers. There were not brushes and no capacitor. Hmm.

The on/off switch is mounted in a small box that seems to big for the little switch. After opening that up I found another component that is called a Start Relay?  It needs to be oriented correctly to work properly and that is why I had the issue initially. There is a warning on the switch housing.

Pretty basic circuit really. The white (neutral) passes through to the motor. Black (hot) goes to one side of the switch and then out to the relay. The relay as scene in the picture has the hot on the back left. The back right is red and goes to the motor and the front right black goes to the motor.
I know about start and run windings. 

Someone has been into the machine before. Is it possible to have the run and start leads (red/black) going to the motor reversed? I don't think it would start if that was the case. How can I test the wiring and the relay to inside it is functioning properly. I don't want the start windings to remain hot. I think I would have an overheated motor at that point. 

Maybe nothing to worry about but I'm trying to learn how that relay works. I usually tangle with centrifugal switches and capacitors. This is new ground for me.

I'd like to get this sorted since I plan to flip it and don't want someone to inherit an issue.

Looks like I need to shrink the pic size to get those attached. I'll work on that.

Thanks
sawnuts

[Roly]

Hello all,

I have restored a number of old (40's through the 60's) in the last few years. This past weekend I see someone was giving away a early 90's Direct Drive 10" saw near me.

I didn't have anything going in the shop so I drove the 4 mile round trip and picked it up.

I was not able to hear the saw run before picking it up so I was very interested in how it ran once I got it home.
I had it flipped upside down on a work cart and when I turned it on it did not sound happy.

I figured I better check out what was going on with the motor because if that is bad the entire unit either needs to be scrapped out or parted out.

After snooping around I had more questions than answers. There were not brushes and no capacitor. Hmm.

The on/off switch is mounted in a small box that seems to big for the little switch. After opening that up I found another component that is called a Start Relay?  It needs to be oriented correctly to work properly and that is why I had the issue initially. There is a warning on the switch housing.

Pretty basic circuit really. The white (neutral) passes through to the motor. Black (hot) goes to one side of the switch and then out to the relay. The relay as scene in the picture has the hot on the back left. The back right is red and goes to the motor and the front right black goes to the motor.
I know about start and run windings. 

Someone has been into the machine before. Is it possible to have the run and start leads (red/black) going to the motor reversed? I don't think it would start if that was the case. How can I test the wiring and the relay to inside it is functioning properly. I don't want the start windings to remain hot. I think I would have an overheated motor at that point. 

Maybe nothing to worry about but I'm trying to learn how that relay works. I usually tangle with centrifugal switches and capacitors. This is new ground for me.

I'd like to get this sorted since I plan to flip it and don't want someone to inherit an issue.

Looks like I need to shrink the pic size to get those attached. I'll work on that.

Thanks
sawnuts

See if Blackhat can explain them as they are used in sealed motors such as hvac compressors.  I only ever worked on one that was a large inline pump pumping cooling oil.     
they work by counter emf that is induced into the winding,  when that voltage gets close to the applied voltage but opposite part of the sine wave it then drops out the relay .   I havent worked with that one in many years,  Blackhat or other hvac guy works with them on a daily basis would be better equipped to answer.   Roly

[sawnuts]

    Roly pid='8126530' dateline='1675130836']
See if Blackhat can explain them as they are used in sealed motors such as hvac compressors.  I only ever worked on one that was a large inline pump pumping cooling oil.     
they work by counter emf that is induced into the winding,  when that voltage gets close to the applied voltage but opposite part of the sine wave it then drops out the relay .   I havent worked with that one in many years,  Blackhat or other hvac guy works with them on a daily basis would be better equipped to answer.   Roly

Thanks Roly,

I've learned a few things. 

In the picture the hot feed from switch goes to upper right lug. Travels through the winding to the run(lower right) which is hot all times.

The Start lead is active when oriented properly and when I flip the relay over it goes open (expected). As long as I have gravity at my house I should be OK. I still don't know how to test if the relay is working OK. The bench test seems OK but I'd need to check from the start lug to neutral with it live to check the actual function.

Start windings are higher resistance than run:

My readings on the motor are

Common-Red 7.3 ohms- start
Common-Bk.   .3 ohms-Run
Red-BK          7.9 ohms

After looking over the pictures I think it is wired correctly.
I'm still not sure the start lead is being cut off.
I think if it wasn't the motor would be complaining and would over heat.

Can anyone verify my thinking is correct or not.

If this little part can take the place of a capacitor and centrifugal switch then I think it is a good thing. I wonder why it isn't used more.

Sawnuts

[Roly]

Thanks Roly,

I've learned a few things. 

In the picture the hot feed from switch goes to upper right lug. Travels through the winding to the run(lower right) which is hot all times.

The Start lead is active when oriented properly and when I flip the relay over it goes open (expected). As long as I have gravity at my house I should be OK. I still don't know how to test if the relay is working OK. The bench test seems OK but I'd need to check from the start lug to neutral with it live to check the actual function.

Start windings are higher resistance than run:

My readings on the motor are

Common-Red 7.3 ohms- start
Common-Bk.   .3 ohms-Run
Red-BK          7.9 ohms

After looking over the pictures I think it is wired correctly.
I'm still not sure the start lead is being cut off.
I think if it wasn't the motor would be complaining and would over heat.

Can anyone verify my thinking is correct or not.

If this little part can take the place of a capacitor and centrifugal switch then I think it is a good thing. I wonder why it isn't used more.

Sawnuts

Now that we have a picture that is a current relay not a potential relay .   The heavy winding is the key.    Here is a link that that tells how they work.     A little different than the potential relay.    LINK                    Roly