"Knurling, cut knurling specifically. Traditional knurling uses two rolls to compress and form the diamond pattern into the material. Cut knurling uses two rolls set at an angle to physically cut the knurling into the material. By threading the blanks onto the fixture I can leave the tool setup (which can be a bit tedious to get it set perfect) and run blank after blank with consistent results." Credit: IG User hillview_wm | Practical Machinist

This is a knurling tool. Its purpose is to press patterns onto metal to improve grip or surface texture. A straight knurl makes parallel lines, often used on knobs and handles. But when you switch to a toothed rolling tool, the metal can be pressed along a thread path to form the actual threads on bolts — a process called thread rolling, which makes the threads stronger and more durable than cutting. | Great leader

Check out how perfect this knurling on this part has turned out. There's a full video how I made it. | my mechanics