Motor problem

[tvidnoviciii]

Well, it's been a while since I updated and it has certainly been a trying 6 weeks or so with the old 'Smith. I've pretty much entered the home stretch on the refurb, all I have left is to repaint the jointer and clean up the extension tables. I spent the better part of last weekends free time aligning the main table, rip fence, miter gauge, and any thing else I could think of. My plan for this weekend was to finish off the jointer.

I spent 3 hrs flattening my waterstones (don't ask) so I could put a fine edge on my jointer knives. Repainting was on tap for this weekend, until last night. I found a band saw (aluminum table with fence and upgrade kit as well as 4 blades) on Craigslist for a song. So I picked it up last night and spent my free time today going over and getting the alignment right on the band saw.

After that was all done I was resawing a 1x4x4" just to see how everything works when I heard a crack and then saw white smoke billowing out of the motor compartment of my MK V. I shut the power off as fast as I could, unplugged and removed the motor pan from the headstock. After everything cleared up, I gave the motor another go. It started up, but started smoking, so I shut it off immediately and removed the motor from the motor pan and took the back cover off of it. I found some black goo throughout the motor, but mostly concentrated near the top of the capacitor (where the wires connect). I also found a ball of what appears to be a waxy paper. Don't know where that came from. none of the wiring appears to be damaged. the only other damage is the waxed string that is wound around the copper coils to hold the windings in place. They appear to be melted. I think that the capacitor blew, but I'm not sure. I think the goo is dielectric that was blown out of the capacitor.

The question is. Is the motor ruined, or can I clean out the goo, replace the capacitor, and use some zip ties around the coils to secure them and give it a go?

Sorry about no pics, I'll try to upload some of them later. BTW, the motor is an Emerson 1 1/8 hp.

[JPG]

See my reply to the original thread.

This thread is superfluous.

[billmayo]

Well, it's been a while since I updated and it has certainly been a trying 6 weeks or so with the old 'Smith. I've pretty much entered the home stretch on the refurb, all I have left is to repaint the jointer and clean up the extension tables. I spent the better part of last weekends free time aligning the main table, rip fence, miter gauge, and any thing else I could think of. My plan for this weekend was to finish off the jointer.

I spent 3 hrs flattening my waterstones (don't ask) so I could put a fine edge on my jointer knives. Repainting was on tap for this weekend, until last night. I found a band saw (aluminum table with fence and upgrade kit as well as 4 blades) on Craigslist for a song. So I picked it up last night and spent my free time today going over and getting the alignment right on the band saw.

After that was all done I was resawing a 1x4x4" just to see how everything works when I heard a crack and then saw white smoke billowing out of the motor compartment of my MK V. I shut the power off as fast as I could, unplugged and removed the motor pan from the headstock. After everything cleared up, I gave the motor another go. It started up, but started smoking, so I shut it off immediately and removed the motor from the motor pan and took the back cover off of it. I found some black goo throughout the motor, but mostly concentrated near the top of the capacitor (where the wires connect). I also found a ball of what appears to be a waxy paper. Don't know where that came from. none of the wiring appears to be damaged. the only other damage is the waxed string that is wound around the copper coils to hold the windings in place. They appear to be melted. I think that the capacitor blew, but I'm not sure. I think the goo is dielectric that was blown out of the capacitor.

The question is. Is the motor ruined, or can I clean out the goo, replace the capacitor, and use some zip ties around the coils to secure them and give it a go?

Sorry about no pics, I'll try to upload some of them later. BTW, the motor is an Emerson 1 1/8 hp.

Get an ohm meter and check the resistance to ground/motor case for each of the power wires. Normally if the wax string is burnt, the motor is bad. If it shows a short, you will have to discard the motor. However if it still shows an open for each motor lead, then you will want to proceed. Change the capacitor, clean out any goo and secure any loose wires using plastic ties to the coil windings so no coil windings , wire or wrapping/strapping extend into the rotor area or touch the motor case. The resistance between the two motor input wires will be in the 1 to 2 ohm range. You can check the resistance between the centrifugal switch leads and the power input wires. You should get one of the following, short, 1 to 2 ohms (run windings), 6 to 8 ohms (start windings) or open. Also check between the capacitor leads and the 2 power input wires. Same choices. Again no short (zero ohms) can exist from any wires to the motor casing.

If no shorts found, put the motor together and try it.

[dusty]

Bill, Reading your response here caused me to dig out the old Crafter's Station Motor. It was declared dead on arrival when I acquired the Crafter's Station. I now wonder about that prognosis.

Using a Fluke 189 the resistance from the yellow wire to the blue wire (run winding I think) is .27 ohms. The start winding (red wire to black wire) measures 5.26 ohms. There are no shorts from any of the four wires to the case.

Is there a chance that this motor has been improperly diagnosed.

[billmayo]

Bill, Reading your response here caused me to dig out the old Crafter's Station Motor. It was declared dead on arrival when I acquired the Crafter's Station. I now wonder about that prognosis.

Using a Fluke 189 the resistance from the yellow wire to the blue wire (run winding I think) is .27 ohms. The start winding (red wire to black wire) measures 5.26 ohms. There are no shorts from any of the four wires to the case.

Is there a chance that this motor has been improperly diagnosed.

Yes, the readings sound good so I would believe the motor is good. I have been able to reuse anymotor that the had no short to ground for the input power wires. Two wires for the run windings and two wires for the start circuit for the motor. Of course, I would do a smoke test later to see what happens.

Having just reversed 3 different model motors this week, I cannot understand why Shopsmith used a relay and switch when a simple DPDT switch would work. The following revised crafter station schmetic is my idea of a simple circuit for the Crafter Station motor and a good schmetic for how to set up the wiring for the reversable motor option for any Shopsith motor. The capacitor and centrifugal start switch are assumed to be in the motor on this schmetic but was poorly shown.
[ATTACH]22527[/ATTACH]
I have been using this this schmetic as the basic for all my reversible motors. An external start current relay and capacitor are used for the AO Smith 3/4 HP motors but go in the same place.

This is how I wire the DPDT switch. Start windings to middle terminals. Power from ON/OFF switch to outside terminals and jumped to opposite outside terminals. I also connect the motor power wires to the first set of outside terminals, all with slip-on connectors to make attaching the wires easy. A real clean setup with no soldering needed.
[ATTACH]22528[/ATTACH]

[dusty]

I agree, Bill, that this could more easily been done with a DPDT switch but that is exactly what the circuit is. The difference being that the change is made using a relay.

The question is really what was the engineer thinking? Why use a dpdt relay rather than a dpdt switch. Contact durability, maybe.

[JPG]

I agree, Bill, that this could more easily been done with a DPDT switch but that is exactly what the circuit is. The difference being that the change is made using a relay.

The question is really what was the engineer thinking? Why use a dpdt relay rather than a dpdt switch. Contact durability, maybe.

The original engineer had(I assume) the requirement to have the power switch in two locations.

Front(accessory) switch turns power on.

Rear(saw) switch turns motor on and reverses direction.

Bill's drawing shows the reversing switch but no power on/off switch that is mentioned in his comments.

As I see it, a 3pdt switch would be necessary to eliminate the relay. I assume a 3pdt switch to fit the safety switch configuration was/is non existent.


I agree the resistance measurements appear normal. Addition of heat may alter that.

Who made that diagnosis? If it was you, do you remember any details that led you to that?

[billmayo]

The original engineer had(I assume) the requirement to have the power switch in two locations.

Front(accessory) switch turns power on.

Rear(saw) switch turns motor on and reverses direction.

Bill's drawing shows the reversing switch but no power on/off switch that is mentioned in his comments.

As I see it, a 3pdt switch would be necessary to eliminate the relay. I assume a 3pdt switch to fit the safety switch configuration was/is non existent.


I agree the resistance measurements appear normal. Addition of heat may alter that.

Who made that diagnosis? If it was you, do you remember any details that led you to that?

Sorry, the ON/OFF switch was deleted in my hurry. It would be in the same location on the schmetic as the original ON/OFF switch was shown. You need two switches for the reverse motor option. One for the ON/OFF and one for the FWD/REV switch.

[dusty]

The original engineer had(I assume) the requirement to have the power switch in two locations.

Front(accessory) switch turns power on.

Rear(saw) switch turns motor on and reverses direction.

Bill's drawing shows the reversing switch but no power on/off switch that is mentioned in his comments.

As I see it, a 3pdt switch would be necessary to eliminate the relay. I assume a 3pdt switch to fit the safety switch configuration was/is non existent.


I agree the resistance measurements appear normal. Addition of heat may alter that.

Who made that diagnosis? If it was you, do you remember any details that led you to that?

It is a long story. I received a PM from a member who was having problems with his Crafter's Station. I tried to help but he had no electrical background and was fearful of working with the wiring. He had been told by a "motor repairman" that the motor needed to be rewound. It is discolored and some of the wax cord is broken and pulled away. With that report, he gave up and offered me the Crafter's Station.

Now you have the rest of the story.

[JPG]

It is a long story. I received a PM from a member who was having problems with his Crafter's Station. I tried to help but he had no electrical background and was fearful of working with the wiring. He had been told by a "motor repairman" that the motor needed to be rewound. It is discolored and some of the wax cord is broken and pulled away. With that report, he gave up and offered me the Crafter's Station.

Now you have the rest of the story.

I think it is worth a second look by Dusty!;)