Southbend Gearhead w/ Dro SB10146PF - Manual (Page 64)

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For Machines Mfg. Since 3/11 Turn-Nado ® Gearhead Lathes O P E R A T I O N
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 83).
Figure 83. 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 84).
Figure 84. 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
85). For example, to cut a 3 1 ⁄
2
thread, select 1 or 3
on the dial.
Figure 85. 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
1 ⁄
4
or 3 ⁄
4
Fractional TPI
For TPI that have a 1 ⁄
4
or 3 ⁄
4
fraction, use position
1 on the thread dial (see Figure 86).
2 7 ⁄
8
TPI
The thread dial is not used for 2 7 ⁄
8
or metric
threading, or diametral and modular pitches (see
Figure 87). The half nut must stay engaged with
the leadscrew throughout the entire threading
operation.
Figure 86. Position for 1 ⁄
4
or 3 ⁄
4
fractional TPI.
Position
1 Only 2¼,2¾,
3¼,3¾
TPI
Figure 87. Half nut stays engaged for 2 7 ⁄
8
TPI.
2 7 ∕
8
Same as
Metric
Threads
Thread Dial
Not Used