Thread: Destroyed motor bearings

So I got my grinder built and I was happily grinding away when my motor seized. a quick disassembly & inspection revealed that the sleeve bearings in this motor are completely trashed. That's what I get for buying an ancient motor for $10 I suppose.

Is there any source of bearings for very old Craftsman tool motors? I couldn't find anything on line. My next stop will be emotorstore to replace the motor.

Question: I used the old trick of mounting the motor on a hinged base & using the weight of the motor (around 12 lbs) to tension the belt. Is there any chance that this resulted in an excessive side load? It's hard to imagine the answer would be yes, since the Marathon manuals for similarly sized motors specify 25 lbs radial load, but they say the only stupid question is an unasked question.

If you can remove the bearings and measure them I am sure you can buy replacements from Applied Technologies or Mc Master Carr.

Here's one place to start looking. 20 Electric Motor Bearing 6203-2RS Sealed:Ball Bearings:VXB

There should be a part number on the race somewhere that you can match up. Replacing them is not a huge deal, but can be interesting. Making friends with a fellow who rebuilds electric motors for a living was one of my best investments.

I doubt it was the side loading. Bearings wear out. They should be regarded as an eventual consumable item if you're going to run motors. Having them last longer requires a little maintenance. Likely this old motor sat for a long time and did not run, or the bearings were going and not completely gone before you bought it. Sitting for a long time, collecting shop dust and not being lubed to keep all the bearing greased up, likely contributed to the end.

The load that you describe is not enough to cause a problem as long as the mounting bracket did not allow a torque component. Did you lube the sleeve bearings before using? Get a motor with real ball bearings and not sleaves and your life will get better. All bearings have a "roll out" specification which means, basically, how many miles did it go? Made by man so it destined to fail.


Take Care,
Richard

OK, the bearings are not removable. They're pressed in, and they're also hidden behind sheet metal collars that are also pressed in. And they're not even roller bearings, they're plain sleeve bearings. Clearly this thing was meant to be put together, but never taken apart.

So I bought a motor from emotorstore; 0.5 HP single phase AC. It was only after I got the motor that I realized they sell fully sealed motors, without the air intake slots. However, the motor is 2 feet away from the grinding wheel, plus I plan to fully enclose the wheel in a plastic waste basket with a water drip like Charlie did, so I think the motor will be safe from metal particles. Fully enclosed motors are a lot more expensive, run hotter, and are almost twice as heavy, which I'm afraid would exceed the side load rating on the bearings. I also have some extremely fine mesh fabric I can use to cover the slots. Hopefully this will be sufficient to keep the motor clean.