Pillow block bearings?

[cmj]

New diy sawmill build.  I have only around 3 hrs of running mill.  Two bearings per shaft.  1 1/4 inch shaft.  Today I could hear a thumping noise and then one bearing blew up.  Inside race cracked in half.   Blade tension was set at 25 ft lbs.  Other bearing on that shaft has play.  I put a little grease in them, but not too much. 
Junk Chinese bearings? 
Or did I do something wrong?  

Checked the other shaft and one bearing rotates in the cast iron.  Outer race is rounded.  Other bearing does not move like that?  

[Larry]

Kasco built a mill with 1-1/2" shafts but they had lots of bearing failures. They increased the shaft size to 2" and which solved the problem.