Drilling for conduit

["Bill Stock" <me7@xxxxxxxxxxx>]

I'd like to run some 2" flexible conduit from the basement to the second
floor (possibly attic). I've already got several smaller holes drilled
through the first and second floors in this wall. I've also got two access
panels on the 'inside' of this center wall. But a recent wiring experience
convinced me that I need a better solution.

I've read that a forstener bit with a right angle adapter is the best tool
for the job. But considering I need to drill about 12", I'm wondering how
difficult it is to control this beast and keep the hole close to straight. I
know from my previous adventures that the three stud walls don't line up too
well. I was hoping that there is some sort of guide that I could mount
between the studs to keep the hole straight.

Any insights appreciated.