Delta SHOPMASTER GR250, Instruction Manual, Page: 9 / 12

9
VARIABLE SPEED
CONTROL
The grinder is equipped with a variable speed control (B)
Fig. 10. When the variable speed control knob is
positioned to the furthermost left position (counter
clockwise), the RPM is 2000. The rotation increases as
the knob is turned clockwise. When the variable speed
control knob is positioned to the furthermost right
position (clockwise), the RPM is 3450.
FLEXIBLE LAMP
The flexible lamp operates independently of the grinder.
To turn the lamp on and off, rotate switch (A) Fig. 11.
WARNING: To reduce the risk of fire, use 40 watt or
less, 120 volt, reflector track type light bulb (not
supplied). A standard household light bulb should not be
used. The reflector track type light bulb should not
extend below the lamp shade.
Fig. 11
A
DRESSING A
GRINDING WHEEL
When dressing a grinding wheel, use a suitable silicone
carbide stick type dresser or the wheel dresser provided
with the grinder, as shown in Fig. 12. Bring the dresser
forward on the tool rest until it just touches the high point
on the face of the wheel and dress the wheel by moving
the dresser back and forth. Repeat this operation until
the face of the grinding wheel is clean and the corners of
the wheels are square.
GRINDING WHEELS
WARNING: THE USE OF ACCESSORIES AND
ATTACHMENTS NOT RECOMMENDED BY DELTA
MAY RESULT IN RISK OF INJURIES.
Attachments
used with this grinder should be rated for 3600 RPM or
higher and be 6" in diameter with a 1/2" arbor hole.
Two aluminum oxide grinding wheels are supplied with
your grinder; one 36 grit and one 60 grit. For best
grinding results, and to maintain good balance, always
keep the wheels properly dressed. Do not force the work
against a cold wheel. The grinding wheel should always
be run at idle speed for one full minute before applying
work. It is recommended that only balanced wheels be
used with your grinder. The use of balanced wheels
adds years to the life of the bearings on the grinder and
by eliminating the most common source of vibration,
more accurate work is accomplished.
ALWAYS maintain
a distance of 1/8" or less between the grinding wheel
and the tool rest. Adjust the tool rests and spark guards
as the grinding wheels decrease in size with use.
Fig. 12