Smooth rods/shafts of what diameter ? Which Linear bearing LM or SC series ? Also please lets know which type of threaded rod you need, metric or ACME, so we can help. I am guessing you need GT2 belt and pulley.
Check my CNC build log to get an idea of what parts you might need @
http://www.ocfreaks.com/diy-cnc-router-mill/Here is a video of my current 3D-Printer (V2) project using 8mm shafts and lm8uuu bearings along with aluminum extrusion and uses GT2 belts which is most common for DIY 3DPs :