Which way round to mount a FK12 bearing ?

[EddyCurrent]

But thinking about it I guess one face of the flange/block could be more accurately machined 90 degrees to the main axis?

Thanks, yes that's what I thought later, anyway I likely wasn't trying hard enough before because I've done it now and quite easy.

Drill largest feasible hole in bracket, in my case about 19mm using a cone cutter (it's hard work and hardly cuts), position bearing block on bracket and clamp, drill mounting holes in bracket using bearing block as a guide, bolt bearing block to bracket with some spacers between, mount in lathe chuck, use boring bar to open hole out to final size.



I think the answer to my original question is this;
The bearings can be used either way around but the face next to the boss is the one that goes up to a bracket. This allows for the fact that the mounting holes are counter bored on the flange face and it's possible that the face next to the boss is more accurately machined.