FAA Powerplant Written Practice Test

What is typically used for polishing commutators or slip rings?

1. Very fine sandpaper

2. Steel wool

3. Emery cloth

4. Polishing compound

The correct answer is: Very fine sandpaper

The use of very fine sandpaper for polishing commutators or slip rings is appropriate due to its ability to smooth out rough surfaces effectively while minimizing the risk of damaging the components. Very fine sandpaper has a grit that can remove oxidation and tarnish without deep scratching the surface, which is essential for maintaining good electrical contact. When using very fine sandpaper, it's important to ensure that the surface remains even and clean to avoid introducing particles that could affect the functionality of the commutator or slip ring. The gentle abrasive nature of very fine sandpaper also allows for better control during the polishing process, leading to a more uniform finish. Other materials like steel wool may be too coarse and could leave behind fine particles that might create issues with electrical conductivity. Emery cloth, while also an abrasive material, might be more aggressive and less suitable for delicate components than very fine sandpaper. Polishing compounds are typically used for a final finish rather than the initial polishing of rough surfaces.