What should be adjusted to ensure safe operation of a bench grinder?

The correct choice focuses on adjusting the tool rest distance to ensure safe operation of a bench grinder. The tool rest is the surface where you place the workpiece to support it while grinding. If the tool rest is set too far away from the grinding wheel, there is a higher risk of the workpiece slipping, which can lead to accidents or injuries. Conversely, if the tool rest is too close to the wheel, it can create excessive friction and risk wheel damage or shatter.

Maintaining the proper distance between the tool rest and the grinding wheel enhances safety by facilitating better control during the grinding process. This adjustment minimizes the likelihood of kicking back, which could lead to injuries. Therefore, ensuring that the tool rest is correctly adjusted is crucial for both effective grinding and operator safety.

Other aspects, like wearing gloves or cleaning the work area, are important for overall safety but do not directly pertain to the operational adjustments needed for the bench grinder itself. Checking the speed of the wheel is also significant, but primarily for ensuring that the wheel can safely handle the workload rather than directly impacting the safety of operation during use like the tool rest adjustment does.