Use and Care Manual

9
Figure 4: Motor wiring diagram
7.0 Operating Instructions
Use the nomenclature drawing in Figure 5 for
reference when various parts and components are
described in the operations and maintenance text.
To order service parts you will find an exploded
view of the grinder in sect. 11.1.1.
Figure 5: General grinder nomenclature
7.1 Applying a workpiece to the disc
face
No matter what size, type or material workpiece
you will be grinding, there are several important
considerations you must understand if you are
going to use the Model J-4421 disc grinder
effectively.
1. Always be certain the wheel guard is
positioned over the disc edge. Materials
abraded from your workpiece will be hurled off
the wheel if the wheel guard is not in position.
2. Always allow time for the disc to come fully up
to motor speed before contacting the
workpiece to the disc. This gives you a chance
to check for possible wheel wobble (looseness
of the disc or motor, or damage from some
earlier operation) before working against the
disc.
3. This is a very powerful and aggressive
grinding device which operates at high surface
speeds. Therefore, you always want to support
the workpiece while using the work table.
"Freehand" presentation of workpiece to the
disc surface is risky to you, to the workpiece,
and to bystanders. It is not possible to
overemphasize the need to keep the
workpiece firmly on the table.
4. The safest position at which to do any grinding
is on the right hand side of the work table
where the disc is moving downward past the
work table. Whenever possible, keep the
workpiece in this area when grinding. In
addition to safety, keeping the workpiece in
this area greatly increases the effectiveness of
the dust control chute and any vacuum dust
control system you might be using. See Figure
6.
Figure 6: Correct table work area
5. The speed and aggressiveness of the machine
means that CONTROL of the workpiece, by
you, is absolutely essential. ALWAYS USE
TWO HANDS to control the workpiece.
6. Because of the speed with which the disc can
grind, heat build-up on work pieces is usually
very rapid. To prevent burns and/or possible
loss of control of any workpiece:
a. Use heat resistant gloves to hold any
workpiece.
b. Where possible and appropriate, use
additional tooling or fixturing to hold the
workpiece when pressing against the grinding
disc.
7.2 Rotary Switch
The rotary switch is located on a post on the left
hand side of the grinder. It is a knob-initiated
switch. See Figure7.
The switch is a Low Voltage Protection (LVP)
switch. When line voltage drops below a safe