TT has the key question
The real question is whether this is something that happens due to flex or if it is a "bent" part. If there is no oscillation when pedaling with no force, then it is due to flex and there's nothing you do about it. If it is happening with no force on the pedals, then the most likely cause is a slightly bent chain ring or crank spider.
Start by checking the crank spider - get a short screwdriver or something you can hold firmly against the seat tube, and hold it perpendicular to the seat tube so that the end just touches the chain ring bolts as you rotate the crank. Most likely you will see that the spider arms of the crank are not the same distance from the frame. You can fix this by placing the bike on its side, resting the opposite crank on a block of wood (this is necessary to support the bearings). Take another block of wood and place it against the spider arm that is too far away/too close to the seat tube, then whack the block of wood with a hammer. Check for movement. If it didn't move enough, repeat, perhaps hitting harder. If it moved too much, flip the bike over and whack it back the other way.
If the crank arm spiders are OK, then check the chain rings (most likely the large ring) in the same fashion. If you find the chain ring deflected, correct it by slipping the jaws of a large adjustable wrench (Crescent Wrench) over the ring, with the jaws set just wider than the thickness of the chain ring. Use the lever arm of the wrench handle to tweak the ring straight.
Even after you've done this straightening technique, flex of the frame, crank, and BB axle may still allow some rub, but it will be significantly reduced. It is HIGHLY unlikely that this problem will be fixed by rotating the crank arm on the BB axle. If things are goofed up like that, rotating the crank arm will just move the problem around.
