Cicero wrote:

Are you sure you're not being too meticulous on this particular job? A 5/8"
galvanised thread isn't likely to be a very fine thread and if your bandsaw is
properly set up it will give good square cut ends on 2" lengths which won't
produce much 'chatter' when the rod is held very lightly in a 4" or 6" vice.

Try a few cuts with the rod held lightly in the vice whilst holding the
projecting rod (opposite end to the cut-off end) with your gloved hands. You
will probably have to put nuts on to raw ends in any case so you might as well
try the quick way which has worked for me whenever I've cut threaded rod on my
bandsaw.

Are you suggesting clamping the threaded rod in a steel vise without
protection?
When I cut using a hacksaw I use aluminium covers for the vice jaws.
I wanted to hold the rod even more securely in the bandsaw, because
it's not nice if it jams and breaks the blade. This is a horizontal
bandsaw with an automatic feed. I usually walk away and do something
else while it's cutting.