16-Speed Gearhead Lathe

O P E R A T I O N

For Machines Mfg. Since 3/11

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.

In.

 

2

3

1

4

4,8,12,16,20,24,

Any Position

28,32,36,40,44,

 

48,56,60,72

 

2,6,10,14,

Non-

18,22,26,

Numbered

30,54

Position

3,5,7,9,

Numbered

11,13,15,

Position

19,23,27

1,2,3,4

2½,3½,4½,

Position

7½,11½,13½

1,3 or 2,4

2¼,2¾,

Position

3¼,3¾

1 Only

278

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).

TPI

4,8,12,16,20,24, Any Position 28,32,36,40,44, 48,56,60,72

Figure 90. Any position on the dial for threading TPI

divisible by 4.

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).

TPI

2,6,10,14,

Non-

18,22,26,

Numbered

30,54

Position

Figure 91. 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 92).

TPI

3,5,7,9,

Numbered

11,13,15,

Position

19,23,27

1,2,3,4

Figure 92. Numbers are selected on the dial for

threading odd numbered TPI.

12 Fractional TPI

Use any opposing number pairs—2/4 or 1/3 on the thread dial for 12 fractional TPI (see Figure 93). For example, to cut a 312 thread, select 1 or 3 on the dial.

TPI

2½,3½,4½,

Position

7½,11½,13½

1,3 or 2,4

Figure 93. Opposing number group are selected on

dial for cutting 12 thread TPI.

-60-

Page 62
Image 62
Southbend SB1053 Thread Dial Chart, TPI Divisible By, Even TPI Not Divisible By, Odd Numbered TPI, ⁄2 Fractional TPI