Final answer:
Certain types of metals should not be ground on a pedestal grinder, including aluminum, bronze, cast iron, brass, pewter, and goldleaf, due to safety risks and potential damage to the grinding wheel.
Step-by-step explanation:
Certain types of metals should not be ground on a pedestal grinder because they pose various safety risks or can damage the grinding wheel. Metals that are softer and tend to clog or smear, such as aluminum and bronze, should be avoided. Cast iron is another metal that should not be ground on a pedestal grinder due to its dusty nature, which can be hazardous to breathe in and can also contaminate the work environment. Additionally, grinding non-ferrous metals like brass or pewter can cause the wheel to load and potentially lead to it shattering. Finally, metals with low melting points, such as goldleaf, can deposit on the abrasive, reducing its effectiveness and possibly causing overheating, which can lead to wheel failure or workpiece damage.