Twist drill bit with straight shank, extra-long, type N, DIN 1869, HSS Application area: Twist drill bit for extremely deep drill holes (not suitable for oil drill holes in crankshafts - special drill bit required for this). The cutting properties (cutting speed, feed rate) must take account of the stability of the drill. Frequent chip removal is just as important as adequate cooling. The achievable drilling performance is very positively influenced by slightly off-centre tip grinding.