my advice..as a smith machine bench presser... get off it for a few reason..
one..your regular bench will suffer because you're not having to take all the weight yourself.
two..it doesn't allow your body to function in it's own range of motion. I'm not talking just pushing straight up and down. A typical bench press does not do that. It comes down and forward and sometimes up and back towards the head/shoulders.
three...it gives a false sense of strength. if you're pressing 405 on the smith you damn sure won't go right over to the flat and bench it.
four.. it puts undue stress on joints and your body in general because throughout the movement your body is forced to work within the bars path instead of it's own not allowing things to stay in line or giving you the best mechanical advantage. When y our wrists, elbows, shoulders, etc. aren't properly in line things go bad fast.
and I could keep going... i have a 12 item list of things I wrote for an article that proves the smith machine is nothing but shit and that's what the cage is for and the pin settings to prevent yourself from getting hurt incase you don't make a lift. I was putting up 455 on the smith machine and had all kinds of joint problems but when I moved over to the flat, I was only able to put up 350 at first. When I moved over to the cage and set it up to myself did I start to see a good strength increase and but growth as well. If you want to develop a stronger bench press, the smith machine is not the answer. There's so many other things you can do to benefit your bench that imho the smith shouldn't ever be looked at for any reason. It's 9am. So if you want me to elaborate more on this I will but right now I'm going to get breakfast.
jason is right..you're shitting in your own flat hat when you use the smith to better your bench.