Final answer:
Adjustable tools should rest on the tool rests of a bench grinder, positioned close to the grinding wheel with a small gap of no more than 1/8 inch for safety and accuracy.
Step-by-step explanation:
On a bench grinder, the adjustable tools should rest on the tool rests, which are designed to provide a stable support while you sharpen or grind a tool. These tool rests should be adjusted so that they are close to the grinding wheel, typically with a gap no greater than 1/8 inch (3 mm) to ensure safety and precision.
It's important to adjust the tool rest to be parallel to the wheel surface and securely tighten it to avoid slippage during operation. When using a bench grinder, always follow the manufacturer's safety instructions and wear the appropriate personal protective equipment.