Machinery Repairman

CHAPTER 5
OFFHAND GRINDING OF TOOLS
AND SELECTION OF CARBIDE TOOLING
CHAPTER LEARNING OBJECTIVES
Upon completing this chapter, you should be familiar with the following:
Identify and explain the use of grinding equipment.
Identify and explain the use of grinding wheels.
Identify and explain the use of single-point cutting tools.
Identify and explain the use of carbide tools
One requirement for advancement in the MR
rating is the ability to grind and sharpen some of the
tools used in the machine shop. The equipment used
for this purpose includes bench, pedestal, carbide, and
chip breaker grinders and precision grinding
machines. This chapter explains the use of these
grinders and how to grind small tools by using the
offhand grinding technique. (We’ll cover precision
grinding machines in a later chapter.)
In grinding, you use the cutting action of an
abrasive to remove metal. In offhand grinding you
hold the workpiece in your hand and position it
against the grinding surface. You must have
experience and practice to do this accurately and
safely. You also must know how to install grinding
wheels on pedestal and bench grinders and how to
sharpen or dress them.
Before you can properly grind small handtools,
single-edged cutting tools, and twist drills, you must
know the terms used to describe their angles and
surfaces. You also must know the composition of the
material from which each tool is made and the
operations for which the tool is used.
Advancing technology has made carbides the
dominate cutting tool in machine shops. You must
understand carbide terminology and the use of carbide
tools.
5-1
GRINDING SAFETY
The grinding wheel is a fragile cutting tool that
operates at high speeds. Therefore, the safe operation
of bench and pedestal grinders is as important as
proper grinding techniques. Follow all posted safety
precautions. Review your equipment operators
manual for other safety precautions and any chapters
of Navy Occupational Safety and Health (NAVOSH)
Program Manual for Forces Afloat, OPNAV
Instruction 5100.19B, that apply to the equipment.
BENCH AND PEDESTAL GRINDERS
Bench grinders (fig. 5-1) are small, self-contained,
and usually mounted on a workbench. Use them to
grind and sharpen small tools such as lathe, planer,
Figure 5-1.—Bench grinder.