Table of Imperial thread pitches on a C1 Lathe with a Metric leadscrew - 1.5mm pitch

RATIO = 1.4000 to 1, PITCH = 2.1000 TPI = 12.0952
Gears required: 36 20 20 30 42 36

RATIO = 1.3622 to 1, PITCH = 2.0432 TPI = 12.4312
Gears required: 36 20 20 30 42 37

RATIO = 1.3263 to 1, PITCH = 1.9895 TPI = 12.7672
Gears required: 36 20 20 30 42 38

RATIO = 1.2923 to 1, PITCH = 1.9385 TPI = 13.1032
Gears required: 36 20 20 30 42 39

RATIO = 1.2600 to 1, PITCH = 1.8900 TPI = 13.4392
Gears required: 36 20 20 30 42 40

RATIO = 1.2293 to 1, PITCH = 1.8439 TPI = 13.7751
Gears required: 36 20 20 30 42 41

RATIO = 1.2000 to 1, PITCH = 1.8000 TPI = 14.1111
Gears required: 36 20 20 30 42 42

RATIO = 1.1721 to 1, PITCH = 1.7581 TPI = 14.4471
Gears required: 36 20 20 30 42 43

RATIO = 1.1455 to 1, PITCH = 1.7182 TPI = 14.7831
Gears required: 36 20 20 30 42 44

RATIO = 1.1200 to 1, PITCH = 1.6800 TPI = 15.1190
Gears required: 36 20 20 30 42 45

RATIO = 1.0957 to 1, PITCH = 1.6435 TPI = 15.4550
Gears required: 36 20 20 30 42 46

RATIO = 1.0723 to 1, PITCH = 1.6085 TPI = 15.7910
Gears required: 36 20 20 30 42 47

RATIO = 1.0500 to 1, PITCH = 1.5750 TPI = 16.1270
Gears required: 36 20 20 30 42 48

RATIO = 1.0286 to 1, PITCH = 1.5429 TPI = 16.4630
Gears required: 36 20 20 30 42 49

RATIO = 1.0080 to 1, PITCH = 1.5120 TPI = 16.7989
Gears required: 36 20 20 30 42 50

RATIO = 0.9882 to 1, PITCH = 1.4824 TPI = 17.1349
Gears required: 36 20 20 30 42 51

RATIO = 0.9692 to 1, PITCH = 1.4538 TPI = 17.4709
Gears required: 36 20 20 30 42 52

RATIO = 0.9509 to 1, PITCH = 1.4264 TPI = 17.8069
Gears required: 36 20 20 30 42 53

RATIO = 0.9333 to 1, PITCH = 1.4000 TPI = 18.1429
Gears required: 36 20 20 30 42 54

RATIO = 0.9164 to 1, PITCH = 1.3745 TPI = 18.4788
Gears required: 36 20 20 30 42 55

RATIO = 0.9000 to 1, PITCH = 1.3500 TPI = 18.8148
Gears required: 36 20 20 30 42 56

RATIO = 0.8842 to 1, PITCH = 1.3263 TPI = 19.1508
Gears required: 36 20 20 30 42 57

RATIO = 0.8690 to 1, PITCH = 1.3034 TPI = 19.4868
Gears required: 36 20 20 30 42 58

RATIO = 0.8542 to 1, PITCH = 1.2814 TPI = 19.8228
Gears required: 36 20 20 30 42 59

RATIO = 0.8400 to 1, PITCH = 1.2600 TPI = 20.1587
Gears required: 36 20 20 30 42 60

RATIO = 0.8262 to 1, PITCH = 1.2393 TPI = 20.4947
Gears required: 36 20 20 30 42 61

RATIO = 0.8129 to 1, PITCH = 1.2194 TPI = 20.8307
Gears required: 36 20 20 30 42 62

RATIO = 0.8000 to 1, PITCH = 1.2000 TPI = 21.1667
Gears required: 36 20 20 30 42 63

RATIO = 0.7875 to 1, PITCH = 1.1813 TPI = 21.5026
Gears required: 36 20 20 30 42 64

RATIO = 0.7754 to 1, PITCH = 1.1631 TPI = 21.8386
Gears required: 36 20 20 30 42 65

RATIO = 0.7636 to 1, PITCH = 1.1455 TPI = 22.1746
Gears required:  36 20 20 30 42 66

RATIO = 0.7522 to 1, PITCH = 1.1284 TPI = 22.5106
Gears required: 36 20 20 30 42 67

RATIO = 0.7412 to 1, PITCH = 1.1118 TPI = 22.8466
Gears required: 36 20 20 30 42 68

RATIO = 0.7304 to 1, PITCH = 1.0957 TPI = 23.1825
Gears required: 36 20 20 30 42 69

RATIO = 0.7200 to 1, PITCH = 1.0800 TPI = 23.5185
Gears required: 36 20 20 30 42 70

RATIO = 0.7099 to 1, PITCH = 1.0648 TPI = 23.8545
Gears required: 36 20 20 30 42 71

RATIO = 0.7000 to 1, PITCH = 1.0500 TPI = 24.1905
Gears required: 36 20 20 30 42 72

RATIO = 0.6904 to 1, PITCH = 1.0356 TPI = 24.5265
Gears required: 36 20 20 30 42 73

RATIO = 0.6811 to 1, PITCH = 1.0216 TPI = 24.8624
Gears required: 36 20 20 30 42 74

RATIO = 0.6720 to 1, PITCH = 1.0080 TPI = 25.1984
Gears required: 36 20 20 30 42 75

RATIO = 0.6632 to 1, PITCH = 0.9947 TPI = 25.5344
Gears required: 36 20 20 30 42 76

RATIO = 0.6545 to 1, PITCH = 0.9818 TPI = 25.8704
Gears required: 36 20 20 30 42 77

RATIO = 0.6462 to 1, PITCH = 0.9692 TPI = 26.2063
Gears required: 36 20 20 30 42 78

RATIO = 0.6380 to 1, PITCH = 0.9570 TPI = 26.5423
Gears required: 36 20 20 30 42 79

RATIO = 0.6300 to 1, PITCH = 0.9450 TPI = 26.8783
Gears required: 36 20 20 30 42 80

RATIO = 0.6222 to 1, PITCH = 0.9333 TPI = 27.2143
Gears required: 36 20 20 30 42 81

RATIO = 0.6146 to 1, PITCH = 0.9220 TPI = 27.5503
Gears required: 36 20 20 30 42 82

RATIO = 0.6072 to 1, PITCH = 0.9108 TPI = 27.8862
Gears required: 36 20 20 30 42 83

RATIO = 0.6000 to 1, PITCH = 0.9000 TPI = 28.2222
Gears required: 36 20 20 30 42 84

RATIO = 0.5929 to 1, PITCH = 0.8894 TPI = 28.5582
Gears required: 36 20 20 30 42 85

RATIO = 0.5860 to 1, PITCH = 0.8791 TPI = 28.8942
Gears required: 36 20 20 30 42 86

RATIO = 0.5793 to 1, PITCH = 0.8690 TPI = 29.2302
Gears required: 36 20 20 30 42 87

RATIO = 0.5727 to 1, PITCH = 0.8591 TPI = 29.5661
Gears required: 36 20 20 30 42 88

RATIO = 0.5663 to 1, PITCH = 0.8494 TPI = 29.9021
Gears required: 36 20 20 30 42 89

RATIO = 0.5600 to 1, PITCH = 0.8400 TPI = 30.2381
Gears required: 36 20 20 30 42 90