https://www.familyhandyman.com/article/cutting-threaded-rod/
Cutting Threaded Rod
When you’re shortening a bolt or threaded rod with a hacksaw, you always mangle the threads at the sawn end, making it tough to get a nut threaded onto it.
THE FAMILY HANDYMAN
When you’re shortening a bolt or threaded rod with a hacksaw, you always mangle the threads at the sawn end, making it difficult to get a nut threaded onto it. Reader Larry LeMasters’ tip produces a much better ending. Thread two nuts onto the bolt at the cutoff spot, tighten them against each other, then saw against the shoulder to create a clean right-angled cut. Next, loosen the nuts and file a slight bevel around the end to clear burrs created by sawing. Then spin off the nuts to clean and realign the threads. Your shorter bolt will work just like a new one from the box.