Don'ts When Grinding.

Don't try to save time by using an untrue wheel.

Don't try to cut with a loaded wheel—a loaded wheel does not cut, but burns off the steel by friction, and surface cracks result.

Don't try to economise with the water service when grinding a hardened tool. It is often better to use no cooling agent than to use it too sparingly.

Don't take too heavy a cut; a grinding wheel is essentially a cutting tool, and has working limitations.

Don't use a dirty cooling agent; such glazes and loads the wheel.

Don't run a wheel above 6,000 feet per minute—glazing will result.

Don't run a wheel below 4,500 feet per minute—the wear on the wheel will be out of all proportion to the metal removed.

Don't force a glazed or loaded wheel—it will break. (To be continued.)