Thread Dial Chart - South bend SB1051 Owner's Manual

13" x 40" Heavy 13 ® EVS Lathe

Thread Dial Chart

The thread dial chart (see Figure 76) can be
found on the front of the thread dial housing. The
dial number indicates when to engage the half
nut for that specific thread pitch.
Find the TPI (threads per inch) that you want
to cut in the left column of the thread dial chart,
then reference the dial number to the right of it.
In.
4,8,12,16,20,24,
28,32,36,40,44,
48,56,60,72
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 ¼
8
Figure 76. Thread dial chart.
Note: The thread dial is not used for metric
threading, diametral pitches, or modular pitches.
For these types of operations, you must leave the
half nut engaged until the turning is complete.
The following examples explain how to use the
thread dial chart.
TPI Divisible By 4
For threading a TPI that is divisible by four, use
any line on the thread dial (see Figure 77).
TPI
4,8,12,16,20,24, Any Position
28,32,36,40,44,
48,56,60,72
Figure 77. Any position on the dial for threading TPI
divisible by 4.
-56-
O P E R A T I O N
Any Position
Non-
Numbered
Position
Numbered
Position
1,2,3,4
Position
1,3 or 2,4
Position
1 Only
Same as
Metric
Threads
For Machines Mfg. Since 5/11
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 78).
TPI
2,6,10,14,
Non-
18,22,26,
Numbered
30,54
Position
Figure 78. Marks are selected on the dial for threading
even TPI not divisible by 4.
Odd Numbered TPI
For odd numbered TPI, use any of the numbered
lines on the thread dial (see Figure 79).
TPI
Numbered
3,5,7,9,
Position
11,13,15,
1,2,3,4
19,23,27
Figure 79. Numbers are selected on the dial for
threading odd numbered TPI.
1
⁄ Fractional TPI
2
Use any opposing number pairs—2/4 or 1/3 on
1
the thread dial for ⁄ fractional TPI (see Figure
2
80). For example, to cut a 3
on the dial.
TPI
2½,3½,4½, Position
7½,11½,13½ 1,3 or 2,4
Figure 80. Opposing number group are selected on
dial for cutting
1 ⁄ thread, select 1 or 3
2
1
⁄ thread TPI.
2