bearing center clean and repair

[lotechman]

I have a big lathe now and along with it came a bearing center with a No 4 morse taper. It felt rough so I took it apart and cleaned then pack with grease. When I used it as soon as there was pressure applied to the centerhole it sent a distinct grinding noise into the spindle. I am taking apart and cleaning again, The assembly is two large 6000 series single row ball bearings and the a thrust bearing made up of two races and a cage of balls.
The one large bearing still has some roughness to the feel of it. The smaller 6000 is smooth as silk. I am gong to take the seals off the large and clean it more. If I cannot get rid of the roughness I guess it is time to order new bearings.
Should I just use mineral oil in the assembly or pack it with grease? Sparingly or pack her solid?

 

[OldMachinist]

Did you make sure to re-install the 2 front bearings in the same orientation in regards to the faces of the bearings as they came out? The bearings are likely precision angular contact bearings and need to be installed correctly to work.

 

[lotechman]

No turn around on the bearings.. front one is a standard 6206 and the back small one I forget but it sits on the end deep in the bore. The thrust washers with bearing grooves and bearing cage between is S 1206.
In any case I checked the 6206 with seals off and oiled... runs smooth...started it on the stub shaft and it started to feel rough. The fit is really tight. reads 1.1810 exactly or 29.9974. The spec says the bore is 30 mm So I am not quite 3 thousandths of a mm clearance. From my novice reading that is not too bad for bearing???.
I polished up the shaft areas with 320 which didn't even touch the hardened material. Still 1.1810
I think I will have to replace bearings anyway with me pushing them on and off several times I doubt they are perfect any longer.
I will leave together and live with it as a rough and ready center rather than one with any precision. For 35 bucks I can get another one which is likely the price of replacement bearings.