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.

[cmj]

Got a chance to mess with the mill.  Pillow bock bearings are replacable in the cast pieces, thats what they move.  Bought a different brand and some replacement bearings.  Mill worked great.   If the shaft was too small i would think the bearing failure would be het related.  no signs of heat issues.  
I did replace only one bearing at first and had another original bearing blow up too.  
I would guess 10 to 12 hours milling after bearing repacement and everything is good so far.  

[Wlmedley]

Don't know if would apply to your build but I used to do mechanic work on large rotary rock drills used in surface mining operations. They used a lot of pillow block bearings and shafts for running pumps,compressors, ect. I learned that when running a shaft though two pillow block bearings one bearing would be a non expansion bearing and the other would be a expansion bearing. The reason being as the machine was ran shaft would warm up and expand ( get slightly longer). If both bearings were non expansion type one or both bearings would fail. Couldn't tell bearings apart until taking them apart.