Hand tools — removing “pinning” from a file clogged by soft metal When filing soft metals, the file teeth can clog with small chips (pinning). What is the proper tool or method to clean the file effectively without damaging the teeth?

Introduction / Context:
Filing performance depends on sharp, open teeth. When working soft metals such as aluminium, copper, or mild steel, chips can wedge between teeth, a condition called “pinning.” This not only reduces cutting efficiency but also scratches the work surface.

Given Data / Assumptions:

• Hand file used on soft metals.
• Clogging observed as bright metallic specks between teeth.
• Objective: restore cutting action safely.

Concept / Approach:
A file card is a specialized, stiff-bristled brush designed to sweep out impacted chips without dulling the teeth. Some file cards include a short-wire brush and a “pick” for stubborn debris. Water, acids, or heating can corrode or soften the file or pose safety risks without improving the mechanical removal of chips.

Step-by-Step Solution:

Verification / Alternative check:
Toolroom best practices endorse file cards as the standard cleaning method; frequent cleaning prolongs file life and improves surface finish.

Why Other Options Are Wrong:

• Water washing: ineffective for mechanically embedded chips.
• Rubbing on wood: may remove loose debris but is inconsistent.
• Dilute acid: risks corrosion and is unnecessary.
• Heating and quenching: damages file hardness and temper.

Common Pitfalls:
Brushing across (not along) the teeth, which can round edges; using wire wheels too aggressively; neglecting chalk, which helps prevent pinning.

Final Answer: