186 Agricultural Mechanics and Technology Systems
Copyright Goodheart-Willcox Co., Inc.
• Secure the workpiece properly and fi rmly before performing any
operations.
• A kickback when using certain power cutting tools can be very
dangerous. This interruption can cause the tool to suddenly jump
backward out of the work and toward the operator. Prevent kickbacks
from happening by removing any nails, screws, or staples from
previously used lumber, and avoid cutting boards through naturally
occurring knots.
• Use only power tools that are in good condition. Report damaged or
broken tools immediately and remove them from service.
• Wear OSHA-approved (ANSI Z87.1) eyewear and/or face protection at
all times. Respiratory (if needed) and hearing protection should also
be worn.
• Tie back and secure long hair, and do not wear jewelry. Clothing
should fi t snugly with no hanging pieces. Wear proper foot protection
when working with heavy materials or heavy tools.
• Properly clean and store power tools to keep them in safe working order.
Additional pertinent safety information can be found in Chapter 5, Safety
and Developing Safe Work Habits.
Drilling and Driving Tools
Power drills and driving tools are machines that use bits or other
attachments to create holes, shape metals, or attach materials using assorted
fasteners. Most of the tools in this broad category are portable, although there
are several prominent examples of stationary machines as well.
Drill Bits
Drill bits are designed to drill holes in many
different materials. The design and construction among
bit types varies greatly, depending on the material
on which they are designed to be used. All drill bits,
however, have three things in common: at least one
cutting edge, a shank that must be attached to the
drill by means of the chuck, and a method of moving
swarf from the hole. Swarf is the shavings created and
displaced by the drill bit as a result of drilling into the
material. See Figure 8-8.
Some common types of drill bits are shown in
Figure 8-9. Most common drill bits are sharpened to a
118° angle at the point because this provides optimum
strength and durability for drilling in most materials.
Drill bits intended for harder steels, such as stainless
steels, are often ground to a 135° angle to begin the
drilling process faster, thus reducing the amount of
time the bit is creating friction without cutting.
David Orcea/Shutterstock.com
Figure 8-8. Swarf created by a working drill bit is
an indication that the moving bit is being applied
with sufficient pressure to cut the material. It is also
a hazard for machine operators. Always wear eye
protection when using a drill, and use a table brush
or similar tool to clean up sharp debris left by the
drilling process.