Standard point angle for general-purpose twist drills What is the usual included point angle for a standard general-purpose twist drill used on steels?

Introduction / Context:The point angle of a twist drill affects chisel edge length, thrust force, chip flow, and wear. A widely adopted standard exists for general-purpose drilling in steels and many other materials.

Given Data / Assumptions:

• Conventional HSS twist drills for general shop use.
• No special-purpose geometry (e.g., split point, cobalt, or parabolic flutes).

Concept / Approach:The most common point angle is 118°. It balances penetration and edge strength, producing reasonable thrust while allowing acceptable chip evacuation in many materials. Harder materials or specific applications may use 135° or other angles, but 118° remains the general baseline.

Step-by-Step Solution:Identify general standard → 118°.Note variants (e.g., 135° split point) for tough materials, but that is not the “usual” case.Answer: 118°.

Verification / Alternative check:Drill manufacturer catalogs and handbooks list 118° as the default point angle for general-purpose drills.

Why Other Options Are Wrong:70° and 100° are too small, increasing thrust and weakening lips; 130° or 150° are more specialized for hard alloys and reduce wandering but are not the default standard.

Common Pitfalls:Confusing point angle with lip relief or helix angle; assuming one angle fits all materials without considering modifications.

Final Answer:118°