So it’s always a joy to pick up a new trick, especially one as simple as putting a hardened edge on mild steel using a drill bit as a filler rod. This tip comes to us by way of [Jody], aka ...

whereas cobalt is typically used for harder materials like cast iron or stainless steel. Tungsten-carbide tipped (TCT) and titanium nitride coated (TiN) drill bits are also popular. HSS is hard ...