Craftsman radial arm saw - motor smoke

[Jim A. Moore]

I just picked up a 1980's vintage Craftsman Radial Arm saw. It sat in in the previous owner's damp garage for probably 10 years. There's some surface rust on the post and the particleboard table was distentegrating.

Whenever I start the motor after a minute or two, it begins to smell like smoke - another minute or two and it will create white smoke. I'm not running it anymore until I figure out what's up.

I've taken off the cowling and blown out the motor with compressed air from my compressor. That seems to have loosened up a bunch of impacted sawdust. However, the spindle is still stiff and the smoke smell still happening.

Any suggestions on next steps most appreciated.

Jim

[Mark Ashmeade]

I just picked up a 1980's vintage Craftsman Radial Arm saw. It sat in in the previous owner's damp garage for probably 10 years. There's some surface rust on the post and the particleboard table was distentegrating.

Whenever I start the motor after a minute or two, it begins to smell like smoke - another minute or two and it will create white smoke. I'm not running it anymore until I figure out what's up.

I've taken off the cowling and blown out the motor with compressed air from my compressor. That seems to have loosened up a bunch of impacted sawdust. However, the spindle is still stiff and the smoke smell still happening.

Any suggestions on next steps most appreciated.

Jim

Electrical components only come with a limited amount of smoke, and it can't be replaced. Once you let the smoke out, it's game over.

It sounds to me like the insulation on the windings or wiring is heating and releasing the smoke. Particularly white smoke. There's a distinctive smell of electrical-sourced smoke vs wood-sourced smoke.

Unfortunately, the motor is probably in need of attention, and that may well just be the end of it, Beyond Economic Repair, as we used to say in the Army. However, what you could do is see if it fits the recall, if it does, get the money and buy a newer RAS. I got a RIDGID RS1000 for $185, and I could not be happier with it. The recall pays out $100.

Linky

[Will Overton]

It is possible that the centrifugal switch is not opening. It sits on the right side [away from blade] and is held on by 2 screws. The points (like cars used to use) wear and the switch needs to be replaced periodically on that saw. I had one for 20 years and changed the switch 3 times. They used to cost $13 from Sears parts. My friend is still using the saw at least a couple of times a weak.

The recall mentioned above [if it's the model I had] will provide you with a new blade guard & table. If you solve the electrical problem, follow up on the recall.

[Jim A. Moore]

I'll take a look at the switch - I've got the motor dismounted.

The spindle is a bit stiff - it rotates when I turn it - but stops quickly if I try to spin it. Is this normal - or could the bearings be sticking?

I've ordered the recall kit - a sign of hubris on my part (probability of fixing motor :-). I'm also interested in using the saw as an overhead router table.

Thanks,

Jim

[Will Overton]

I just went out and spun the blade on my Delta. When I let go the blade did not make a full revolution before it stopped. The Delta has an Emerson motor, probably the same as yours.

[Chip Lindley]

Motor disassembly should show you if the motor is fried beyond redemption. If you see no burned insulation in the motor windings, you may be ok. Find the start capacitor to see if it's case is burned. A new capacitor needed, would be your quick and lucky fix.

Otherwise, the centrufugal switch must be checked to see that it slides freely up/down the motor shaft under spring pressure. Any dirt dobber mud caked inside the motor??

IF the motor IS fried, those RASs are a dime a dozen on CL. They rarely bring over $100, so you can use the Emerson recall to buy another!

[Lee Schierer]

My Craftsman RAS has a brake that comes on and stops the blade when the power is turned off. The brake doesn't allow the motor to spin freely when it is powered off. If the brake is sticking it could cause excess load on the motor; however, I suspect that the bearings have gone bad on the motor from lack of use. You may or may not be able to replace them.

If you let the smoke out, you will not be able to replace the motor, but you might get it rewound at a local shop. the rewind price will likely be more than the cost of a new saw.

[Jim A. Moore]

Was just thinking about this - and smoke doesn't happen until the motor comes up to speed. If I cycle the motor on and off - I don't get a smoke smell or actual smoke. The capacitor does not look burned. The windings I can see look ok.

I've got the motor dropped off the yoke - now working on separating it from the mount chassis.

[Will Overton]

Jim,

You should be able to get to the c. switch without removing more than the cover. The reason I suspect the switch is that it is supposed to open after the motor comes up to speed. The fact that the problem is delayed after the motor starts makes me think something in that circuit is getting hot, but only after the motor is up to speed, when the switch should open.

[Jim A. Moore]

Last night, I made use of some non-flammable tuner cleaner I've had sitting on a shelf - blasting the motor coils and bearings and the centrifugal switch.

The armature spun more easily - so I went to be a bit more encouraged.

This morning, I pluged it in and ran in - no smoke smell - no smoke in my eyes.

Ideally, I'd like to take the motor apart and really clean it well. My main obstacle with that task is getting the big nut on the spindle taken off so I can slide the armature out of the housing...haven't figured out how I'm going to do that yet.

Thanks for the advice and counsel.

[Jim A. Moore]

Then things took a turn for the worse - sadly by my own hand.

As I mentioned, I wanted to take the motor apart and clean it - to make sure all the impacted sawdust was cleaned out.

I wasn't able to get the motor completely apart - but was able to get a toothbrush in and around a few more areas.

After reassembling the motor - it no longer runs well. On startup it can do several things - go slowly in the wrong direction, run slowly in the forward direction, sit there and hum. If I pull the spindle out - something clicks and the motor spins fast. If I mount a blade, the motor will just sit there - until I pull the spindle (or push from the non-blade side). Then it will spin, but trip the circuit breaker.

I'm feeling rather stupid for taking a well working motor and turning it into a zombie motor. I'd rather not give up yet - I owe it to the motor to try something. What can I try?

[Will Overton]

... something clicks and the motor spins fast ...

I stand by my original diagnoses.

[Dick Strauss]

Blow compressed air through it to clear out the dust buildup. I assume you pushed the dust with the toothbrush to somewhere where it interferes with the motor operation. Blow air in every hole you can find and at every angle imaginable. You'll be surprised at how much dust comes out of it! If you are lucky, the starter circuit will be able to make contact again.

Take care,
Dick

[Jim A. Moore]

I decided the most interesting part of the problem was that the saw started up once I pushed the armature in.

When I took the motor apart, I had to remove a spacer on the blade end of the armature. The spacer was basically a large unthreaded nut - held in place by friction and a roll pin.

The roll pin was not centered in the spacer - it was midway between the center of the spacer and the end. I wondered if I put it back in the same orientation as when I removed it.

So - I backed out the pin, removed the spacer - and reinstalled the other way - pushing the armature back into the motor.

Bingo - motor is back running.

Things I've learned about electic motors:

1) Blow them out with compressed air regularly to keep them operating
2) Don't whack on the end of the armature with a hammer (though I used a wooden mallet - I'd be more gentle in the future)
3) Support the armature directly when removing or installing a roll pin in the spacer nut.

[ken gibbs]

Even a small child knows that the "smoke" is installed in an electric motor at the motor factory. So electricity consists of smoke. When you see the smoke get lose, the electricity has gone out of the motor and will not work. It can only start fires. Take the motor to a rewind shop and have some more smoke installed. Then your motor will work again.