Cold chisel practice — recommended cutting angle for mild steel In workshop operations involving hand chipping of mild steel using a cold chisel, what should be the approximate cutting (wedge) angle of the chisel to balance penetration and edge strength?

Introduction / Context:
The cutting (wedge) angle of a cold chisel is a fundamental shop-floor parameter that controls how effectively the chisel penetrates the work and how long the cutting edge survives. For mild steel, the angle must be large enough to prevent premature edge failure but not so large that the chisel merely ploughs without cutting. Understanding the typical values used by fitters and tool makers helps avoid poor finish, excessive effort, or chipped edges.

Given Data / Assumptions:

• Material: mild steel (low carbon steel, relatively ductile).
• Tool: hand-held flat cold chisel.
• Objective: select a practical wedge angle for efficient cutting with good edge life.

Concept / Approach:
A smaller wedge angle produces a sharper edge and easy penetration but makes the edge weak and prone to chipping on tougher metals. A larger wedge angle strengthens the edge but requires higher force and may cause rubbing. Workshop practice standardizes wedge angles by material: softer metals (copper, aluminium) use 40–50°, mild steel uses about 60°, and harder steels use 65–70°. This balances penetration, chip formation, and durability.

Step-by-Step Solution:

Verification / Alternative check:
Standard shop manuals and training texts list typical cold chisel angles by material class, with mild steel around 60°. Observed field practice corroborates this range for acceptable edge life and chip control.

Why Other Options Are Wrong:

• 30°, 45°, 50°: too small for mild steel; edge chips or mushrooms quickly.
• 70°: robust but requires excessive force; better for hard steels, not mild.

Common Pitfalls:
Using one angle for all materials; blaming poor cutting solely on hammer force instead of adjusting wedge angle and lip clearance.

Final Answer: