Turning Archive 2007

Subject:
Stuck Face Plate, damaged bearing Questions.

Barry Irby
>Ruth had a face plate stuck and many of us tried to help. Then she discovered a noise that we suspect is a damaged bearing. With apologies to Ruth, I am borrowing her troubles to ask a few questions.

If there is a dimple or "Brunell" in the bearing race because of an impact to the shaft would it tend to "run out" or improve with use? I'm thinking that there might be a little dimple with the corresponding little "ridges" of displaced material around it. So if you ran the lathe, wouldn't the balls in the bearings tend to mash the little ridges back down and at least eliminate that part of the problem? That is, instead of the ball have to go up over the wall, down into the crater, and up over the other wall, it would just be left with the little dimple. Seems like it would smooth out a little. How bad would it have to be to cause the bearing to lock up?

Did heating the shaft have anything to do with this? How hot do you have to heat a bearing race to soften the steel and make it more likely to cause a dimple?

One of my suggestions was to file a notch in the edge of the face plate and set a chisel in the notch and hit it sharply. My thinking was that this would impart a rotary force to the faceplate with less of the force being perpendicular on the shaft and at right angles to the bearings, thus less likely to cause a dimple. The force needs to be rotary. I don't suppose there is any way to support the shaft while we give it a whack? On my lathe none of the shaft is exposed when the face plate is on. Wonder if it would help to put a block of some sort of metal or hardwood under the face plate and then put a wrench on it?

Just sort of musing here, I realize we should do those things necessary to avoid getting things stuck on the shaft.

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