thanks guys for all the very helpful responses. lots of good info here. two setup's yielded very similar measurements, so i feel pretty good about the measurements. i chucked up the BB in a lathe prior to welding, and the faces should have been very close to parallel. not the best practice but i cant really afford a BB facer at this point. i suppose that i could use a bike shop after the fact.

Can you all offer some incite into which tubes you tack in first? when do you complete weld a joint, and when do you measure?

Thanks