研鑽[kensan] diligent study 鑽り火[kiribi] striking sparks with flint and steel or by rubbing sticks together (usu. to start a fire) 鑽孔機[sankouki] boring machine 鑽り出す[kiridasu] to quarry
鑽孔[sankou] boring 鑽る[kiru] to start a fire (with wood-wood friction or by striking metal against stone) 自己研鑽[jikokensan] self-improvement 火鑽り[hikiri] hand drilling (to start a fire)