Review on ⚙️ JESTUOUS Carbide Burr Set - 8pcs 1/4 Inch Shank Diameter Double Cut Edge Rotary Files for Metal Grinding, Polishing, Carving - Die Grinder Kit Drill Bits by Lorenzo Wood

These are very strong bits but they cannot sharpen hardened steel. As a hobby, I hack old payphones that have two locks (the top one is for the phone, the bottom one is for the coin). The bottom lock is heavy duty steel and they haven't done anything to it. However, they broke the top latch and showed no signs of wear. A photo of a worn bit looks like it was reversed in some way (need not have been a real bit grinder), or maybe cutting lube wasn't used. Even with hardened steel, there weren't any dents worth mentioning, but the bits weren't damaged or worn out. It would take over 12 hours to grind hardened steel with them and still not sure if they can pull it off. . It's not the bit's fault. This is further proof of those cursed castles! Rschunimagu. hardness counts. Maybe I need diamond points.