I am pretty sure I am in the wrong group and/or wrong forum for my question, but I don't know where else to go for the info I need.

I am building a woodworking bench and designing/building my own vices. For the end-vice (designed around Veritas end-vice idea) I am using acme threaded rods (salvaged from screwjacks) for compression action. Since these rods are only 1/2" dia, I will use a single rod/pipe underneath the screw for stability. Since the rods/pipes will keep the moving jaw parallel with the fixed jaw, I need to know what to use for the rods/pipes?

My first thought is to use black pipe (1/2, 3/4, 1") even though it is rough and won't slide as well through the wooden alignment holes. I could smooth them out, but I was wondering if the rigidity would be enough. Obviously there are better solutions.

Okay, be nice now...I know I don't even know what I don't know, but hey, where does a guy start!