STROTON Cobalt Drill Bit Set (1/16-1/4 Inch, 13PCS), M35 High Speed Steel Twist Drill Bits for Stainless Steel, Hard Metal, Cast Iron, Plastic and Wood

Product Advantages: (1) Split Point Desigh Tip starts drilling immediately with less force and eliminates "walking" across the work surface. (2) Holds up better than generic high-speed steel,Cobalt gives high-speed steel more heat and wear resistance. (3) This drill bits set is made of Premium Cobalt (80,000 dollars per ton). (4) The M35 5% cobalt drill bits can cut through Stainless steel and Hard metal,Hard wood, although they can be used for softer materials such as Aluminum,Plastic. Some Important Tips about drilling stainless steel and hard metal:     (1)Controling the drill speed from 200 to 1000 RPM would make it easier for you to drill holes on stainless steel. ________________________________                 Stainless Steel                       ____________________________       Drill diameter               RPM             ____________________________       ?3/16                       1000~700     ____________________________       3/16-3/8                     700~350     ____________________________       3/8-1/2mm                   350~200 ________________________________     (2)Add stainless steel tapping oil or engine oil to prevent the stainless steel from overheating and forming a very hard oxide layer.It also works adding some vinegar,soy sauce or water if you don't have engine oil.