Chapter 8 Power Tools 213
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in machine shops or shops that do a great deal of precision automotive or
engine work. Engines undergoing comprehensive repair and rebuilding have
parts that require this type of grinding.
Sanders
Sanders are machines that use abrasives to smooth rough wood surfaces
and to remove small amounts of a wood surface. Sanders may also be used in
metalworking applications. In fact, many grinders can be set up with sanding
attachments. Like grinders, sanders may be portable or stationary.
Portable sanders include disk sanders, belt sanders, sheet sanders,
random orbital sanders, detail sanders, and oscillating multi-tools. Stationary
sanding machines include several types of belt sanders, disk sanders,
oscillating spindle sanders and various combinations of these examples.
Sanders operate by many different methods. Some spin around a single
axis like grinders, while others vibrate, oscillate, orbit, or rotate around
multiple axes.
Sander Abrasives
Sanders use abrasive particles that are bonded to
fl exible backings of reinforced paper, cloth, or plastics,
Figure 8-48. These backing materials are held in place
on the sander by a variety of methods. Belts and drums
are held by friction, while some sanders use clips to
hold sanding pads in place. Others rely on adhesive or
a hook-and-loop system to fasten pads to the sander.
As a sanding consumable is used, the effectiveness of
the abrasive degrades as the abrasive is worn away
from the backing material.
Disk Sanders
Although similar to angle grinders, disk sanders
usually operate at slower speeds than angle grinders
and do not necessarily come equipped with the same
type of guards. As stated earlier, angle grinders are
typically used with the disk at an angle of 15° to 30° to
the surface of the material, whereas disk sanders are
often held fl at to sand or polish large surface areas.
Disk sanders are aggressive and capable of removing large amounts of
material quickly. They have a tendency, however, to leave behind distinctive
circular marks or striations that may require additional sanding. A disk
sander might be used to rough-shape wood or as a fi nishing tool on metal
surfaces, such as refi nishing the hood of a tractor.
Portable Belt Sanders
Belt sanders use a paper or cloth belt coated with abrasive that wraps
around a pair of rotating drums. The resulting motion is a sanding action that
moves in a straight line as opposed to the circular motion associated with
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Figure 8-48. Sanding belts are commonly a cloth-
based belt with abrasive material bonded to one side.