A die grinder is a handheld power tool used to grind, sand, hone,
polish, or machine material, typically metal but also plastic or
wood. They are usually pneumatically driven, although versions
with electric and flexible shaft drive also exist. Their name
comes from one of their earliest and archetypal applications,
tool and die work, where they are used to create the precise
contours of dies or molds. Especially before the advent of
widespread CNC usage, they were heavily relied upon for
contouring via manual skill comparable to a sculptor's. CNC now
provides much of the contouring for die and mold interior
surfaces, but die grinders are still very useful for hundreds of
cutting needs, from sculpture-like contouring in the absence of
CNC, to cut-off of bar stock, to any of the cutting and grinding
needs of fabrication, such as in the work of welders,
boilermakers, millwrights, ironworkers (steel erectors), sheet
metal workers (such as auto body workers and HVAC technicians),
to woodworking (especially cabinet making), hacking, and other
hobby or business pursuits. Die grinders are often used for
engraving, cylinder head porting, and general shaping of a part.
Die grinders are very similar to rotary tools, and in fact some
people do not make any distinction between them. The difference
between a die grinder and a rotary tool is mainly one of mental
classification rather than etic traits. Die grinders are thought
of as industrial tools, whereas rotary tools are thought of as
tools for the residential mass-consumer end-user. There is
overlap, though, as many consumers own die grinders, and many
industrial users have rotary tools. The distinction is not very
significant. Die grinders may feature heavier construction (such
as being made of die-cast metal rather than molded plastic) and
higher top speeds for the spindle
Methods of cutting action
The cutting may be done in various ways, including:
Grinding with bonded abrasive stones (called by various names,
such as mounted stones, mounted points, or grinding points)
Machining with a burr or small drill bit or endmill
Sanding with coated abrasive, such as small drums made of
sandpaper mounted on an expanding rubber mandrel (also called
an arbor)
Honing with fine-grit mounted points
Lapping with lapping compound and a mounted lap to embed it
Polishing or buffing with cloth or fiber drums or flaps and
polishing compound
Types of cutters
Mounted stones of many shapes and various [small or medium]
sizes (also called mounted points or grinding points)
Burrs of many shapes and various [small or medium] sizes (also
called rotary files)
Small drill bits
Small endmills
Small disc-shaped saw blades or milling cutters
Small abrasive cut-off wheels, which work like saw blades
except via abrasive cutting rather than sawing per se
Small sanding drums
Small sanding flap wheels
Small cloth or fiber wheels, drums, and flap wheels (for
holding polishing compound)
Mounted laps
