When a nut is rounded, there’s only a few ways to safely loosen it without damaging the thread.
Here’s a way that involves filing down 2 sides of the nut, so you have 2 flat edges, then with a close fit spanner and a wedged in screw driver, you can then have the leverage needed to open it.
website:https://www.jhmindustry.com/
Shanghai Jian & Mei Industry and Trade Co., Ltd. is the company which manufacture and export fasteners and metal hardware, founded in 2006, with import-export authority. Now, 80% products export to all over the world and 20% sell in domestic market.