Rek-O-Kut ball bearings: optimal material to mitigate divot wear?

Table was new old stock. But an open box item. No divot when acquired. Only oil used was SAE 20 3-in-1 blue label. Tried a ceramic ball and noticed divot wear starting after very low hours (probably about 30 hours).

Doesn't Tungsten have a higher hardness than Ceramic?

Do we know what material the ball was that ROK used? I'm thinking that material is the safest bet as ROK vetted that material back in the day.

It's not necessarily the hardness, it's the interaction of the two surface structures. As i mentioned, ceramic and quite a few metals don't like being rubbed together. I would guess, the ball chosen was an M50 grade ball. Having said that, there are quite a few grades of tungsten carbide balls. If going that route, get the highest grade one you can.
 
I'd be kind of surprised if the OE ball material was anything other than common chrome steel. If the original was rusty, thats probably the case.

Is the spindle stainless, or is it just steel?
 
Not sure what ROK used for the stem. According to a 1964 Billboard article about Koss buying Rek O Kut, it is mentioned that ROK was in bankruptcy since 1953. So given they were under price pressures for an extended period, I'm not sure what kind of material was used for the platter stem (regular steel, stainless, pot metal etc).
 
A magnet will tell much. Its going to be some flavor of steel, but it may be one of the stainless types. The 300 series stainless is weakly magnetic, others are more magnetic. It might also just be chromed steel. A magnet will really stick to that.

so not being particularly familiar with the setup here, does the ball turn against a thrust plate down inside the well, or does the spindle turn against the ball?
 
A magnet will tell much. Its going to be some flavor of steel, but it may be one of the stainless types. The 300 series stainless is weakly magnetic, others are more magnetic. It might also just be chromed steel. A magnet will really stick to that.

so not being particularly familiar with the setup here, does the ball turn against a thrust plate down inside the well, or does the spindle turn against the ball?

I'd guess some combo of the two happens.

In designs with captive balls on the shaft and a thrust plate, is the design intent for the ball to spin with the shaft (truly captive?) Or is the ball generally free to rotate?
 
I had some turntable with that setup, can't recall which, but the end of the spindle was turned to an inverse taper, forming a cup for the bearing to sit in. It wasn't polished or particularly smooth so friction basically held the ball to the spindle and it rotated against a polished plate down in the hole. The one I have that goes the other way, the bearing sits in a plastic well and the bottom of the spindle is polished smooth with a very slight dome shape.

usually you can get a fairly good idea of which parts are meant to spin against each other just looking at the surfaces. The two smooth ones are generally the bearing surfaces. Both of those tables I mentioned you can remove the ball bearing from. The Weathers has the plastic well and needs a slight push on the bottom to eject it. I think the other may have been an AR table that I used to own, if not I just don't remember at this point. Either way the ball wasn't captive at all, in fact I seem to recall losing the original because it fell out of the well when I turned it over before realizing it was ever there.
 
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