Southbend South Bend 16 SPEED GEARHEAD LATHE SB1053 - Manual (Page 62)

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For Machines Mfg. Since 3/11 16-Speed Gearhead Lathe O P E R A T I O N
Thread Dial Chart
Find the TPI (threads per inch) that you want
to cut in the left column of the thread dial chart
(see Figure 89), then reference the dial number
to the right of it. The dial numbers indicate when
to engage the half nut for a specific thread pitch.
The thread dial chart can also be found on the
front of the thread dial housing.
4,8,12,16,20,24,
28,32,36,40,44,
48,56,60,72 Any Position
In.
Non-
Numbered
Position
Numbered
Position
1,2,3,4
Position
1,3 or 2,4
Position
1 Only 2,6,10,14,
18,22,26,
30,54
3,5,7,9,
11,13,15,
19,23,27
2½,3½,4½,
7½,11½,13½
2¼,2¾,
3¼,3¾
2 7 ⁄ 8
1
2 3
4
Same as
Metric
Threads
Figure 89. Thread dial chart.
Note: The thread dial is not used for metric
threads, or diametral and modular gear turning.
You must leave the half nut engaged from the
beginning until the threads/gears are complete
for these types of operations.
The following examples explain how to use the
thread dial chart.
TPI Divisible By 4
For threading a TPI divisible by four, use any
line on the thread dial (see Figure 90).
Even TPI Not Divisible By 4
For threading a TPI that is even but not divisible
by 4, use any of the non-numbered lines on the
thread dial (see Figure 91).
Figure 90. Any position on the dial for threading TPI
divisible by 4.
4,8,12,16,20,24,
28,32,36,40,44,
48,56,60,72 Any Position
TPI
Figure 91. Marks are selected on the dial for threading
even TPI not divisible by 4.
Non-
Numbered
Position 2,6,10,14,
18,22,26,
30,54
TPI
Odd Numbered TPI
For odd numbered TPI, use any of the numbered
lines on the thread dial (see Figure 92).
Figure 92. Numbers are selected on the dial for
threading odd numbered TPI.
Numbered
Position
1,2,3,4 3,5,7,9,
11,13,15,
19,23,27
TPI
1 ⁄
2
Fractional TPI
Use any opposing number pairs—2/4 or 1/3 on
the thread dial for
1 ⁄
2
fractional TPI (see Figure
93). For example, to cut a 3 1 ⁄
2
thread, select 1 or 3
on the dial.
Figure 93. Opposing number group are selected on
dial for cutting 1 ⁄
2
thread TPI.
Position
1,3 or 2,4 2½,3½,4½,
7½,11½,13½
TPI