Anyone smoke a JET 1236 motor?

[Tim Root]

First an intro from a noob: I'm Tim, I've been turning since I was 14 or so, but a long hiatus while married and raising kids. My father gave me his old Craftsman/King Seely (1949) when he finally bought a JET 1236 about 10 years ago. I just retired the Craftsman and picked up a JET for very decent change. I've had it a few weeks and it works the nuts. Tonight, while turning my first burl bowl it started making this "whacking" noise. I shut it down and noticed a puff of smoke come from the fan end of the motor and that burnt electrical stink. I rotated the headstock and removed the cover, all was in order except the set screw laying there inside the housing. I quickly indentified where it belonged on the stationary-half pulley of the motor. I replaced it and found the other one a bit loose and same with the spindle pulley ones. I fired it back up and all seems well. The motor starrts and runs smoothly, so I'm wondering what that smoke and stink were? Any clues folks?

Thanks in advance!

Tim

 

[GeorgeH]

Welcome, Tim, glad to have you engaged. Burning electrical "odors" don't always mean an electrical overheating problem, it sometimes means that something got into the motor and heated up and the electrical insulation became a secondary victim. If I recall correctly, the motor for the 1236 piggy backs onto the spindle housing. Wondering if some debris accumulated in the air intake and, either from blocking air flow and overheating the motor or from finding an ignition source from within the debris field you got something smoking. If you've got everything tightened up (did you use some light hold thread locker?) and its running quietly I'd blow the motor out with compressed air and wouldn't worry about it until some other clue surfaces. If you run the motor for a spell, then turn the lathe off and feel the motor housing temperature, you'll get a good idea whether the motor is actually overheating. If you have an amp meter you could check the current demands under operation to see how close they come to the specs. Just remember, when you're calculating current demands, this is an AC circuit not a DC circuit.

 

[Tim Root]

Thanks George

It seems to be working fine, but I know that stink when it did it, I am an electronics tech by trade. I hope you're correct there, all I can do is wait and see now. After I did the tightening I rechucked the burl to start the hollowing process and had sanded the outside just prior to that. I need to add that light threadlocker because I didn't think to put any on at the moment. I will do so tomorrow though, I hate loose parts! I did read here about someone's reeves drive having a similar loosening problem as well. That prompted me to go back out and grease the shafts of the motor and spindle pulleys and the speed control rack slide as well. Much nicer. Already seeing benefits of hooking up with this group.

 

[Bill Grumbine]

I tried once, but it was too hard to get it lit.

The loose parts, which you apparently fixed, could have been the culprit. The smells can be close, close enough to make you worry.

 

[Tim Root]

Loose parts...

Nah, it was that ozone-smelling wisp of smoke that came out of the motor that got me ;-)

 

[Vaughn]

I tried once, but it was too hard to get it lit. ...

Dang it Bill! You beat me to it.

Sorry Tim, but I don't have any advice to add that hasn't already been mentioned. I do hope it was a one-time anomaly.

 

[Tim Root]

Nope, it going on the fritz

Not an anomoly. I was finishing up a burl bowl tonight, turning outboard, and it got flakey again. Sometimes it didn't start and I had to give it a spin, then it would run fine. It was clattering again and I noticed some sparking inside the fan cowl as it did it. I took off the fan cover and blew out the wood dust to no avail. I'm guessing the capacitor or the start mechanism is crapping out. The setscrews were still tight. My Dad says to take it to an electric motor shop as they can likely repair or replace it for better, cheaper than another JET. I'll let you know how it turns out eventually. I really like this lathe otherwise, and considering I only paid $250 for it, I really can't complain. Oh, and the bowl

 

[Bill Grumbine]

Yeah, that sounds like the capacitor. I was thinking of that before, but you said the motor ran fine, so I discounted that possibility. I had a Jet bandsaw that did that when the capacitor melted down. It would run, but it had no power at all.

Vaughn, twisted minds think alike!

 

[Tim Root]

Got it!

While contemplating the problem, it came to me that the motor runs fine when I spin/start it by hand. There's a mechanical capacitive start contact behind the fan rotor, under the rear motor cover. Once I removed the centrifugal actuator and checked the contact, the problem was apparent. Like a set of points from long ago, the contact on the upper (moveable)part was cooked. That was what smoked and caused sparks. It left the capacitor out of the circuit (open) during starting (so it wouldn't start!), then the centrifugal thing opens the contact for a direct connection to the 120VAC to the motor(that's why it would run when I spun it up by hand). I filed the contact flat again and replaced everything, making sure there was good pressure on the contact for starting and it opened plenty far enough away when running. Plugged it in and VOILA! she's all better! I'll bet there was some wood dust in there, reducing the contact's continuity and raising it's resistance, hence heating and smoking it, that caused the whole shebang to crap out. We'll see how it lasts now.

PS: A new JET motor is $193 + S&H, motor shop ballparked me $65-150 for a repair FYI. Total cost to me, ZIP this time!

PPS: Safety Warning - IF YOU DO THIS AT HOME YOURSELF BE SURE TO UNPLUG THE UNIT FIRST!!!!

 

[loberg]

I took a motor to a repair shop for those conditions. They replace those contacts and told me to blow out the motor every once in a while. I put a sheild on the jointer motor so dust does not get in the motor and regularly blow out the other motors in the shop. Glad you found the problem.

 

[Mark Mandell]

So, Actually, you were, um, like smokin' wood? Far out, Dude!

So, like what kinda wood was it, man?

And, um, like, where can we get some?