A cutoff tool is a hand-held, pneumatic or electrical device typically designed to mount a grinding or cutting wheel. They can be utilized in situations where a saw or other cutting tool would be unwieldy, as they are typically available in a variety of sizes and configurations. Small cutoff tools may be held in one hand and operated with a lever-activated push button, while more powerful units can require two hands to operate. These larger units often have a second handle that is mounted perpendicularly to the main body of the tool to give a larger measure of control. Cutoff tools can be used to cut and grind a variety of different materials, depending on how the cutting wheel is equipped.
These tools are often available in both straight and angled versions. The former has the surface of the cutting wheel mounted perpendicularly to the body of the tool. The latter has a spindle that is mounted so that the surface of the cutting wheel is parallel to the body of the tool. The angled versions are sometimes known as angle grinders, and are usually used for light to heavy grinding applications in addition to cutting.
Smaller cutoff tools are typically suited to cut through thin materials and are not made for heavy grinding applications. A small tool with a cutting wheel may be used for light grinding, though that may result in the wheel breaking. This could cause an injury from flying pieces of broken cutting wheel, so using a grinding wheel can be much safer. Some cutoff tools are designed to accept only cutting wheels, while others can mount a variety of different wheels.
Different tools can typically mount a variety of cutting and grinding wheels. Many use an abrasive composite-type wheel, similar to what is used in an abrasive saw. A grinding wheel used with a cutoff tool may be similar to a miniaturized grinding wheel used on a bench grinder. These types of cutting and grinding wheels can allow a cutoff tool to cut through metal easily.
In regard to lathes, the term cutoff tool is used for an entirely different purpose. This cutoff tool, also known as a parting tool, is used to separate the work piece from the excess material mounted to the lathe. These are used in both wood and metalworking. For woodworking, the parting tool is typically a hand-held chisel with a very specific shape. The chisel is simply pressed into the wood where a cut is desired, while the lathe is typically run at half speed. Metalworking uses a similar process, though the parting tool is typically mounted with a bracket instead of being hand-held.