In the case of a left-handed screw requiring to be cut with these compound wheels, only one connecting-wheel is employed, instead of the two required for a simple-gear seen in Fig. 1125.

By referring to the Figure 1127, it will be seen that the spindles of the connecting-wheels are quite distinct from each other, and from the screwing-wheels as before stated, so that they cannot affect the relative speed of the wheels between which they are placed ; consequently the wheels mentioned in the Tables of compound wheels, are, like those for simple wheels, calculated as if no auxiliary wheels are to be used. The Tables of compound wheels are numbered 11 and 12. In Table 11, the steps per inch to be cut are situate between their respective four wheels, above, below, to the right, and to the left.

Table 9. Simple-Gear Wheels To Be Used Vrith A Lathe-Screw Having 4 Steps Per Inch

Numbers of Steps per inch in Screws to be cut

Numbers of Teeth on Mandril-wheels.

Numbers of

Teeth on Screw-wheels.

24

20

120

23

20

116

22

20

110

21

20

105

20

20

100

19

20

95

18

20

90

17

20

85

16

25

100

30

120

15

20

75

14 1/2

40

145

14

20

70

30

105

40

140

13 1/2

40

135

13

20

65

40

130

12 1/3

40

125

121212

20

60

25

75

30

90

40

120

11 1/2

40

115

11

20

55

40

110

Numbers of Steps per inch in Screws to be cut.

Numbers of

Teeth on

Mandrilwheels.

Numbers of

Teeth on Screw-wheels.

10 1/2

40

105

10

20

50

30

75

40

100

9 1/2

40

95

9

20

45

40

90

8 1/2

40

85

8

30

60

25

50

40

80

7 1/2

40

75

7

40

70

6O

105

6 1/2

40

65

80

130

6

40

60

50

75

30

45

60

90

5 1/2

40

55

80

110

5

40

50

60

75

4 3/4

80

95

Numbers of Steps per inch in Screws to be cut.

Numbers of Teeth on

Mandril-wheels.

Numbers of

Teeth on Screw-wheels

4 1/2

40

45

80

90

4 1/4

80

85

4

50

50

60

60

90

90

3 3/4

80

75

3 1/2

40

35

80

70

3 1/4

80

65

3

40

30

60

45

80

60

2 3/4

80

55

2 1/2

80

50

2 1/4

80

45

2

60

30

80

40

90

45

1 3/4

80

35

1 1/2

80

30

1 1/4

80

25

1

80

20

100

25

Table 10. Simple-Gear Wheels To Be Used With A Lathe-Screw Having 2 Steps Per Inch

Numbers of Steps per inch in Screws to be cut.

Numbers of Teeth on Mandril-wheels.

Numbers of

Teeth on Screw-wheels.

15

20

150

14 1/2

20

145

14

20

140

13 1/2

20

135

13

20

130

12 1/2

20

125

12

20

120

11 1/2

20

115

11

20

110

10 1/2

20

105

10

20

100

9 1/2

20

95

9

20

90

30

135

8 1/2

20

85

8

20

80

25

100

30

120

7 1/2

20

75

40

150

7

20

70

30

105

40

140

6 3/4

40

135

6 1/2

20

65

40

130

6 1/4

40

125

Numbers of Steps per inch in Screws to be cut.

Numbers of Teeth on Mandril-wheels.

Numbers of

Teeth on Screw-wheels.

6

20

60

30

90

5 3/4

40

115

5 1/2

20

55

40

110

5 1/4

40

105

5

20

50

30

75

40

100

43/4

40

95

4 1/2

20

45

40

90

4 1/2

40

85

4

20

40

25

50

30

60

3 3/4

40

75

80

150

3 1/2

20

35

40

70

60

105

80

140

3 1/4

40

65

80

130

3

20

30

30

45

40

60

Numbers of Steps per inch in Screws to be cut.

Numbers of Teeth on Mandril-wheels.

Numbers of Teeth on

Screw-wheels.

2 3/4

40

55

80

110

2 1/2

40

50

6O

75

2 1/4

40

45

80

90

2

20

20

50

50

60

60

1 3/4

40

35

80

70

1

40

30

60

45

1 1/4

40

25

80

50

1

40

20

50

25

9/10

100

45

8/10

100

40

75

30

7/10

100

35

6/16

100

30

5/10

100

25

4 /10

125

25

Table 11. Compound Wheels, To Be Used With A Lathe-Screw Having 2 Steps Per Inch. Driving Wheels

20

20

20

20

20

20

20

20

20

20

20

70

29.75

23.8

19.833

17.

14.875

13.222

11-9

10818

9.916

9153

8.5

85

70

28.

22.4

18.666

16.

14.

12.444

11.2

10.181

9.333

8.615

8.

80

70

26.25

21.

17.5

15.

13125

11.666

10 5

9.545

8.75

8.076

7.5

75

65

48.75

39.

32.5

27.857

24.375

21.666

19..5

17.727

16.25

15.

13.928

150

65

45.5

36.4

30.333

26..

22.75

20222

18.2

16.545

15.166

14.

13.

140

65

42.25

33.8

28.166

24.1428

21.125

18.777

16.9

15.363

14.083

13.

12.071

130

65

39.

31.2

26.

22.285

19-5

17.333

15.6

14.181

13.

12.

11142

120

65

35.75

286

23.833

20..428

17.875

15.888

14.3

13.

11.916

11.

10.214

110

65

32.5

26.

21.666

18.571

16.25

14.444

13.

11.818

10.833

10.

9.285

100

65

30.875

24.7

20.583

17.642

15.437

13 722

12.35

11.227

10.291

9.5

8.821

95

65

29.25

23.4

19.5

16.714

14.625

13.

11.7

10.636

9.75

9.

8.357

90

65

27.625

22.1

18.4166

15.785

13.812

12.277

11.05

10.045

9.208

8.5

7.892

85

65

26.

20.8

17.333

14.857

13.

11.555

10.4

9.454

8.666

8.

7.428

80

65

24.375

19.5

16.25

13.928

12.87

10.833

9.75

8.863

8.125

7.5

6.964

75

65

22.75

18.2

15166

13.

11.375

10111

91

8272

7.583

7.

6.5

70

40

14.

11-2

9.333

8.

7.

6.222

5.6

5.091

4.666

4.307

4.

70 65

40

13.

10.4

8.6C6

7.428

6.5

5.777

5.2

4.727

4.333

4.

3.714

40

12.

9.6

8.

6.857

6.

5.333

4.8

4.363

4.

3.692

3.428

60

40

11.

8.8

7.333

6.285

5.5

4.888

4.4

4.

3666

3 384

3142

55

40

10.

8.

6.666

5..714

5.

4.444

4

3.636

3.333

3076

2.857

50

40

9.

7.2

6.

5.142

4.5

4.

3.6

3.272

3.

2.769

2.571

45

35

2625

21.

17.5

15.

13125

11.666

10.5

9.545

8.75

8.076

7.5

150

35

24.5

19.6

16.333

14.

12.25

10.888

9.8

8.909

8.166

7.538

7.

140

35

22.75

18.2

15.166

13.

11.375

10.111

9.1

8.272

7.583

7.

6.5

130

35

21.

16.8

14.

12.

10.5

9.333

8.4

7.636

7.

6.461

6.

120

35

19.25

15.4

12.833

11.

9.625

8.555

7.7

7.

6.416

5.923

5.5

110

35

17-5

14.

11.666

10.

8.75

7.777

7.

6.363

5.833

5.384

5.

100

35

16.625

13.3

11.083

9.5

8.312

7388

6.65

6.045

5.541

5115

4.75

95

35

15.75

12.6

10.5

9.

7.875

7.

6.3

5.727

5.25

4.3846

4.5

90

35

14.875

11.9

9.916

8.5

7.437

6.611

5.95

5.409

4.958

4.577

4.25

85

20

25

30

35

40

45

50

55

60

65

70

Driven wheels.

Driving Wheels.

Driven wheels.

Table 12. Simple And Compound Wheels To Be Used With A Lathe-Screw Having 1 Step Per Centimetre

Numbers of Steps per centimetre in Screws to be cut.

Driving wheels.

Driven wheels.

1

50

50

60

60

30

30

1.1

50

55

100

110

1.2

50

60

100

120

1.3

50

65

100

130

1.4

25

35

50

70

100

140

1.5

20

30

40

60

50

75

16

25

40

50

80

1.7

50

85

1.8

25

45

50

90

Numbers of Steps per centimetre in Screws to be cut.

Driving wheels.

Driven wheels.

1.9

50

95

2.

20

40

30

60

21

50

105

2.2

25

55

50

110

2.3

50

115

2.4

25

60

50

120

2.5

20

50

40

100

2.6

25

65

50

130

2.7

20

100

45

120

2.8

25

70

20

100

40

140

2.9

40

50

40

145

3.

20

60

30

90

Numbers of Steps per centimetre in Screws to be cut.

Driving wheels.

Driven wheels.

3.1

20

62

30

40

30

124

50

20

20

155

20

30

30

62

3.2

25

80

20

50

40

80

3.3

20

50

55

60

3.4

25

85

20

75

60

85

3.5

20

70

30

105

3.6

25

90

3.75

20

75

40

150

3.8

20

75

95

60

3.9

20

100

60

130

4.

20

80

25

100

4.1

20

82

30

20

30

82