Jet J-720R, Operating Instructions And Parts Manual

Page: 16 / 40

16
8.5 Moving drill head along arm
1. Release drill head by pushing head locking
handle downward (see Figure 7-1).
2. Turn handwheel to move drill head along arm,
clockwise to move right, counterclockwise for
left movement.
3. When drill head is at desired position and no
other adjustments to spindle location are
required, pull locking handle upward to secure.
8.6 Rotating arm on column
NEVER swing drill press arm
on column unless you are absolutely certain
the drill press base is firmly attached to the
shop floor.
If the arm is moved off its position
directly above the base and the base is not bolted
to the floor,
THE DRILL MAY TIP OVER AND
CAUSE SERIOUS INJURY TO THE DRILL
PRESS OPERATOR,
and will certainly result in
damage to the drill press itself.
1. Release lower locking handle on column.
2. Swing arm using handle to required spindle
position.
3. When spindle is positioned correctly and no
other adjustments are required, tighten locking
handle.
8.7 Setting spindle speed
Spindle speeds are established using the gear
change levers on upper right-hand side of drill
head (See Figure 7-1). The shorter of the two
levers operates a two-speed mechanism which
puts the gearbox in either high gear or low gear. A
HI/LOW indicator on the upper left hand side of the
drill head identifies selected speed range.
The longer gear change lever operates a three
speed gearbox mechanism. A detent in the middle
of the lever travel indicates when lever is in
intermediate gear position.
This gearbox set-up offers a total of six spindle
speeds which may be selected. The speed
selected clearly depends on the position of
both
gear change levers .
A chart on front of drill head shows gear change
lever positions for speed selection. A similar chart
is included in
sect. 10.0 of this manual.
On the gear change chart you will also find
recommended drill sizes for the various speeds
which are selectable.
These recommendations
are only approximate. With the wide variety of
drill types and coatings available, as well as cutting
fluids, and the even wider variety of work piece
materials which you might be machining – you
should consult with your tooling, coolant and/or
work piece suppliers to determine the best spindle
speed to use for any specific drilling operation.
Do not attempt to change
gears while spindle is turning. This may cause
serious damage to spindle drive system.
Allow spindle to stop completely before attempting
to change gears. If the gear change lever you want
to move does not slip easily into the new position,
jog the motor briefly using the control lever. Then
allow spindle to come to a stop before attempting
to change gears again. Repeat this jogging
process, as necessary, until the gears match up
properly for changing.
Plan for quill movement
during high speed spindle rotation. High speed
rotation without quill travel will increase
spindle temperatures.
8.8 Limit switches
The J-720R has limit switches on the quill which
cut power to the drive motor when quill has
reached either upper or lower limit of its travel. This
system is designed to prevent gearbox damage if
power feed mechanism is engaged – damage
which would occur if quill were to bottom out
against upper or lower limit of quill travel. In the
event of failure of either limit switch there is also a
safety clutch mechanism which will slip when travel
limits are reached.
However, while you are able to use virtually the full
travel of the quill for drilling or other operations, the
drill press operator typically sets both rate of feed
(travel-per-revolution of the spindle), and depth of
cut (quill travel to make the required cut).
These two operations are described here:
8.9 Setting feed rate
Feed rate is set using the knob on front of drill
head. See Figure 8-1. The knob can be rotated to
select any of three different feed rates, plus a
neutral position where power feed does not
operate on the quill. Line up rivet on dial with
desired feed rate on scale.
Figure 8-1