If you're planning on cutting aero or standard tube shapes, then you need to pick up the Park Tool SG-7 Oversized Adjustable Saw Guide. With it you'll accurately hack trough steerer tubes from 1-1/4in to 1-1/2in, integrated seatposts, and any airfoil shape up to 3.5in. Contact pads are included  to protect tubes and frames so you don't scratch the areas you still want intact.