Electric motor diagnosis

[jo1010]

This is an old motor from a lathe....single phase 1/2hp.....seems to have power but there is a rumbling / resonance when running. I've never messed with these before.....I presume bearing fault....but no discernible sideways float present...
Have a listen..

Is bearing replacement feasible or economical...I can id bearing on disassembly but are they obtainable ( it's a GEC motor)
Ta.

 

[AVI_8]

I changed the bearings on an air compressor electric motor, not a difficult or expensive job.
Take the old bearings to a bearing supplier, in my case they had them in stock.

 

[Dragnet]

There are many reasons for bearing failure. It's reasonably straightforward to break a motor open, and if it's old you may well find it's a simple lack of lubrication. I've just cleared a seized dehumidifier synchronous motor with bearing journals surrounded by felt. All bone dry and the shaft seized to the journal. A polish with valve grinding compound and filling all the felt with oil, it runs quietly. I've replaced several bearing races in motors, and all have been available off the shelf for a few pounds. Sometimes a lot of heat is required to remove the old ones, if they're seized or pitted, but yours seem like they'd pull off.

The worst case is that your bearings are unobtainable (very unlikely) and you'd have to slightly ream the hole to fit an available size, or make up your own. Or get a new motor - I'm sure there are plenty around on the shelves of the sort of people who frequent this forum! I know I have several of various sizes, but whether there are any that match yours I don't know.

 

[AVI_8]

If you’re not sure where to start with stripping it and pulling the bearings have a look at some you tube videos, an electric motor is an electric motor, take pictures while you’re getting it apart, not trying to tell my granny how to suck eggs by saying that, they’re simple things to strip down.

 

[Turbo]

There is a strong possibility that motor has oilite bushings and not roller bearings.
If so you might just need to soak the felt wipers in light machine oil.

That sounds more like there is something causing the rotor to be off balance. It could be part of the centrifugal switch.

 

[Jack_K]

With the way an electric motor is you won't usually find any play but if the bearings are removed they might be obviously noisy.

 

[jo1010]

Yes thanks guys....defo oilite bearings in this....what I've also noticed is that there's an amount of vibration when the motor is on the lathe so something is not quite right in there.
Can certainly strip the bells off and maybe soak the felts for a start....and I'm wondering whether turning the pulley end bell through 180 degrees might be worth trying before anything else....
Also I previously had this apart to check the electrical connections and noticed that the rotor seemed a really tight fit inside the stator...like it needed effort to pull and insert when I removed it.....shouldn't it be an easier sliding fit? And if so what can I do about it if anything.....