metric m42 8% cobalt twist drill bits set for stainless steel and hard metal (1mm-10mm/19pcs) stroton <b>product advantages</b>:<br> <br> (1) <b>3 steps desigh tip</b> starts drilling immediately with less force and eliminates "walking" across the work surface. <br>(2) holds up better than generic high-speed steel,<b>cobalt</b> gives high-speed steel more heat and wear resistance. <br>(3) this drill bits set is made of <b>premium cobalt</b> (80,000 dollars per ton).<br>(4) the m42 metric 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.<br><br> <b>some important tips</b> about <b>drilling stainless steel and hard metal</b>: <br> &nbsp &nbsp (1)controling the drill speed from 200 to 1000 rpm would make it easier for you to drill holes on stainless steel. <br> ________________________________<br>&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp stainless steel &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp <br>&nbsp &nbsp ____________________________ <br>&nbsp &nbsp &nbsp drill diameter &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp rpm &nbsp &nbsp &nbsp &nbsp <br>&nbsp &nbsp ____________________________<br> &nbsp &nbsp &nbsp ≤5mm &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp 1000~700<br>&nbsp &nbsp ____________________________<br> &nbsp &nbsp &nbsp 5-10mm &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp 700~350 <br>&nbsp &nbsp ____________________________ <br> &nbsp &nbsp &nbsp 10-15mm &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp 350~200 <br>________________________________<br><br> &nbsp &nbsp (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.