The reason that nobody is answering your question about bar weight on the Smith Machine is because there is no standard weight for a bar on a smith machine.
If you detached the bar from the machine, it's either going to weigh 35 pounds or 45 pounds depending on the brand of smith machine. However, most smith machines counterbalance the bar somewhat, which lessens the effective weight of the bar (not to mention the inertial stabilization that the racks provide by keeping you on the same vertical path has a huge impact on "real" work done).
If you don't believe me, unhook the bar on the smith machine, raise it over your head, stand back, and let it drop. Have a buddy to the same thing right next to you with a basic olympic bar. While the smith bar will "glide" down, the regular olympic bar will predictably fly towards the ground.
This begs the question -- how much assistance is the Smith Machine giving you? If the smith bar doesn't fall as fast as a regular "unhindered" olympic bar, then it's technically lighter -- but how much? Some smith machines will try and give you an answer in the documentation somewhere on the machine, but even that is suspect.
If you absolutely, POSITIVELY have to use a smith machine, I'd go conservative and count the bar as zero. You'll be much better off trying to make gains that way IMO.