[deadlykitten]

hy kstrauss, you are right, that's a center drill ... my english, my bad

yes, it is indeed 60*, but it works well for those parts where is only required to have a "chamfer" instead of a sharp corner

even if 60* is the most common shape, there are also center drills with different angles, or with 2 tapers

sometimes, if a thread is required, a 60* will be less agressive and allow the tap to guide smoother into the hole, compared to a 90* / kindly

ps : is it always raining ?

[kstrauss]

Deadlykitten your English is fine!

Rather than a small angle it is often recommended that the spot drill have an angle greater than the usual 118-degree drill point to ensure precise starting of the drill. For example, Guhring (a manufacturer of outstanding quality drills) offers spot drills with a 142-degree angle. See https://www.guhring.com/ProductsServ...omResults=True for some details of their products.

[deadlykitten]

hello , yup, they have to have a greater angle, in order to assure that the following drill will start cutting from it's center towards the exterior

another condition is that the pilot diameter has to be greater then the following drill, in order to assure that his flutes will avoid contact with the walls when going inside the previous hole

drills are generally listed inside catalogue as h7; in that link that you shared, pilots are h6 ... it is ' some kind of saying ' that the pilot will deliver a bigger hole / kindly