First use of 3/16" multi -use drill bit, the carbide tip shattered on one side. I bought these bits specifically to drill hardened (heat treated) steel knife blades. These I have bought already hardened. I don't want to anneal the blades, not even the tangs,so, I bought these bits. The 1/4" seemed to hold up well, so I will probably buy more 3/16" bits and return them to be repaired as needed when broken bits pile up. If I find I have a real problem, I'll start spot annealing the tangs and give you guys a really scathingly negative review.