# Lathe Motor Bearing Lubrication



## ChuckB (Apr 6, 2016)

Sorry if this is the wrong place to post this.. only section I could find pertaining to motors.

I have a Westinghouse 3/4 HP motor on my lathe. I had it apart to redo the wiring and decided to look at the bearings. It has a single row ball bearing type on each end. It is sealed on the armature side, but the outer side is open and slides into a round pocket a little wider than the width of the bearing . On the outside on each end cover of the motor is a single screw in plug with a channel angled toward the round pocket. Even If I did pump grease into the hole, there would be nowhere for the pressure to go, and might pop out the seal. When I filled the pocket with grease and pushed the end cover on the motor, grease was forced out of the open hole.. maybe this was the right procedure?

OR..

I am wondering if I am suppose to use some kind of oil instead of grease?? Seems oil would leak out.. any thoughts?

Another interesting note.. when the motor is mounted, the plugs are facing downward.


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## Micke S (Apr 7, 2016)

Bearings should never be filled with grease, which is a common misunderstanding.  What happens if a bearing is completely filled is that is is hard to turn at speed and can overheat. If the bearings are good I would clean them, grease moderately and reinstall them. Otherwise replace them with new double sealed C3 bearings, which are factory-greased for their entire service life.


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## ChuckB (Apr 9, 2016)

Micke S said:


> Bearings should never be filled with grease, which is a common misunderstanding.  What happens if a bearing is completely filled is that is is hard to turn at speed and can overheat. If the bearings are good I would clean them, grease moderately and reinstall them. Otherwise replace them with new double sealed C3 bearings, which are factory-greased for their entire service life.



I went ahead and reassembled the motor, using grease on the bearings. Ran it for a half hour and everything appears to be fine.


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## Ulma Doctor (Apr 9, 2016)

a lot of the old motors used oil for lubrication of the bearings.
a gallery is filled with oil, then oil will seep past dust shields and lubricate the bearings
grease is generally too thick to use the same method

if the bearing was making noise before the addition of grease, the damage has already been done.
i'd consider taking it down again and replace the bearings.
you can get C3 bearings from many sources, ebay being one
measure the shaft, the outside diameter, and thickness to select the bearing
if the measurements seem odd when you record them, it's possible that it's a metric bearing
6003 ,6203 ,& 6205 are all common motor bearings
the motor you have there may have inch series bearings they start with R
like R10 , R12, R16


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## ChuckB (Apr 9, 2016)

Ulma Doctor said:


> a lot of the old motors used oil for lubrication of the bearings.
> a gallery is filled with oil, then oil will seep past dust shields and lubricate the bearings
> grease is generally too thick to use the same method
> 
> ...




The bearing in the picture is a NOS one that I bought from ebay. It's a New Departure 8504, which is the exact brand that was in there before. It is single shielded, with the open side facing outward toward the reservoir.  The bearings were not making noise before, but I crushed the shield on one using the wrong puller. Stupid thing to do, since I had the right puller sitting on the shelf. I wanted to go with oil, but was afraid of leaks. When I disassembled it, there was no sign of oil, only grease. The motor is easy to remove, but very hard to reinstall due to it's mounting position and weight. I will keep an ear open for bearing noise and take action if need be.


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