Cutting threaded rod can be a pain. I’ve seen all sorts of ways to hold it, cut it, prepared it etc… There’s one way though that’s very simple, quick and reusable. Just make a split-nut.
Here’s how to do it…
Step 1. Put a nut in a vise that matches your threaded rod’s specs.
Step 2. Cut a slot in it. I’m using a dremel tool here. You can use a hacksaw or jigsaw (if you hold the nut differently), or even a file.
Note: I suggest against using a diamond disc like I am in this photo. The carbon from the diamond and heat from the friction will cause hardening of the steel. It’s possible to end up with a nut that is very difficult to close. It seems like a small deal, but it’s happened to me.
Use a proper cut-off wheel and good safety goggles.
Step 3. Use the thing. Slip the nut(s) on the threaded rod, orient them so when the vise closes the nut clamps the rod.
Step 4. Do whatever. Now you can safely cut your rod with a hacksaw or dremel or jigsaw or whatever. A quick file once it’s cut and you are done.
I keep a set of magnets on my bandsaw stand. I just toss my split nuts on those magnets so they are always at hand when I need them.