Grizzly G0769 Lathe User Manual


 
Model G0768/G0769 (Mfd. Since 8/15)
-59-
Thread Dial Chart
INDICATOR TABLE
9 1-8
1-8
1-8
1-8
1, 4, 7
12
18
24
All Others
TPI SCALE
Figure 97. Thread dial chart.
The thread dial chart is located on the headstock,
as shown in Figure 96.
Find the TPI (threads per inch) that you want to
cut on the thread dial chart (see Figure 97), then
reference the scale number to the right. The scale
numbers indicate when to engage the half nut for
a specific thread pitch as indicated by the thread
dial.
7
1
3
5
Thread Dial
TPI Dial Number
1, 4, 7
10, 11, 13, 14, 16,
19, 20, 22, 32, 40, 44
Figure 99. Dial positions for other TPI.
All Other TPI: Use lines 1, 4 or 7 (see example
in Figure 99).
The following examples explain how to use
thread dial and thread dial chart.
TPI Divisible by 3: Use any line on the thread dial
(see example in Figure 98).
7
1
3
5
Thread Dial
TPI Dial Number
9, 12, 18, 24
1–8
Figure 98. Dial positions for threading TPI
divisible by 3.
When threading, use slowest speed pos-
sible and avoid deep cuts, so you are able to
disengage half nut when required to prevent
a carriage crash!
When the first cutting pass is complete, the opera-
tor disengages the carriage from the leadscrew
using the half nut lever. The operator returns the
carriage for the next pass and re-engages the half
nut using the same thread dial setting to resume
the cut in the previous pass.
Apron Threading Controls
The half nut lever engages the carriage with the
leadscrew, which moves the carriage and cutting
tool along the length of the workpiece for thread-
ing operations (see Figure 96).
The numbers on the thread dial (Figure 96) are
used with the thread dial chart to show when to
engage the half nut during inch threading.
Note: The thread dial is not used for metric
threading. For that type of operation, you must
leave the half nut engaged from the beginning
until turning is complete.
Thread Dial
Figure 96. Apron threading controls.
Half Nut
Lever
Thread Dial
Thread Dial
Chart
Engaged
Half Nut
Lever
Disengaged