Center hole is used to provide support for long shafts that are machined on a lathe and or cylindrical grinder. The tail stock locates the center drilled hole by its cone feature and allows the part to rotate about its center accurately.

1. Center holes without protecting chamfers  type A.

2. Center holes without protecting chamfers  type B.

3. Dimension for threaded center holes standard type F.

4. Dimension for threaded center holes standard type H.