Jet GH-26120ZH, Operation And Maintenance Instructions

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12.4 Thread Cutting
Threading is performed in multiple passes, with an
initial cutting depth of about 0.2 mm, and
decreasing depth in succeeding cuts. It is
recommended that test cuts be made on scrap
material and the results checked before proceeding
with regular material.
1. Move thread selection lever (F, Figure 31) to
desired direction, for right-hand or left-hand
threads.
NOTE: The overrunning clutch in the
apron will prevent the tool post from feeding
for left-hand threads. It will only feed when
right-hand threads are being cut.
Figure 32
2. Set speed levers (E
1
,E
2,
Figure 31) to desired
speed. Use the lowest speed possible when
threading.
3. Select desired thread using thread pitch
levers (G
1
,G
2
,G
3
, Figure 31) in conjunction
with the charts on the headstock. These charts
are also included in
section 16.10 of this
manual.
4. Engage the half nut (Figure 33). The half nut
must be engaged during the entire threading
process when doing metric, diametral, and
modular threading.
Figure 33
5. When tool reaches end of cut, disengage and
back out the tool to clear the workpiece.
6. Reverse direction to allow cutting tool to return
to its starting point.
7. Repeat the process until desired result is
obtained.
NOTE: When a special thread must be cut that is
not found on the chart, move thread change control
lever (G
1
, Figure 31) to position, and lever (G
3
)
to
IV
, then reset the change gears.
13.0 Adjustments
Adjustments to the lathe,
especially those involving alignments of
bearings, spindle, leadscrew, clutch, etc.,
should only be performed by qualified
personnel, as improper alignments can damage
the machine and/or create a safety hazard.
Turn off main switch and press
emergency stop button before making
adjustments to the lathe.
13.1 Chuck Jaw Reversal
The three jaws on the scroll chuck are reversible,
to hold stock with larger diameters. See Figure 34.
Loosen the two screws with the provided hex key,
remove the jaw, and rotate it 180-degrees. Re-
install the jaw, and tighten each screw in
increments until fully tightened.
Figure 34 – Chuck jaw reversal
13.2 Gib Adjustments
After a period of time, some of the moving
components may need adjustment for play due to
wear.
Do not overtighten gib screws as this can
hasten wear to components.
Saddle – Turn screws (A, Figure 35) on either side
of the saddle at the rear to adjust drag on the
saddle.
Cross Slide – Gib screws are located at front and
rear of slide opposite to one another (B, Figure 36).
To adjust drag, loosen rear gib screw one turn, and
tighten front gib screw a quarter turn. Rotate the
handwheel to check the play. Repeat as needed
until slide moves freely without play. Gently tighten
rear gib screw.