Cut bolts clean with no shredded threads
To cut bolts to length with a hacksaw, I made a simple bolt-holding vise jig from a piece of scrap hardwood. After drilling a hole the length of the scrap, where shown, I cut partially through the center of the jig with my bandsaw. When tightened in a bench vise, those jaws pinch the bolt firmly for a wiggle-free cut.
And here's a trick to clear those threads that invariably get messed up during the cut: Thread a nut up the bolt before you cut; then remove it after. This cleans up any mashed threads. If you plan to cut more than one bolt to the same length, mark the location of the bolt's tip while in the jig for a quick reference point.
—Don Stanley, Jefferson, Ore.