Change gears charts for metric threading on the 7x mini-lathe

Charts with standard gear set for metric mini-lathes: 20, 20, 30, 35, 40, 40, 45, 50, 50, 60, 60, 80, 80.

When for B and C gears ANY is shown on tables, it means that  B and C gears are only necessary as a idler gear. On  these cases, use for B and C a pair of gears with the same teeth number and a suitable size to mesh with A and D.

To calculate change-gears combination for threading on any lathe you can use the following formula:  TPI = (B/A) x (D/C) x leadscrew pitch


Mini-lathe change gears combination for threading

Metric threading on lathes with metric 1.5mm pitch leadscrew

 

Simplified chart

For the mini-lathe banjo and with the original gear set. 

MM / PITCH AB
C
D
ERROR %
0.25 2060
40
80
0.0000
 0.3  40
50 20
80
0.0000
0.35 2050
35
60
 0.0000
0.4  2060
40
50
0.0000
0.45  20
60
45
50
0.0000
0.5 4060 3060
0.0000
0.62060
6050
0.0000
0.7 35
6040
500.0000
0.7520606040
0.0000
0.8 40
60
40
50
0.0000
1 60453060
0.0000
1.25 40605040
0.0000
1.5 40606040
0.0000
1.75 35606030
0.0000
2 60505045
0.0000
2.5 50606030
0.0000
3408080
20
0.0000
3.535
6080
200.0000
4
80606030
0.0000
4.560808020
0.0000
5
50
30
8040
0.0000 

 

 

Extended charts

Many of these combinations don't fit the mini-lathe banjo, though can be used with other banjo styles. 

MM / PITCH AB
C
D
ERROR %
TPI
0.252045
30
80
0.0000 101.600
0.2520
60
40
80
0.0000 101.600
0.252080
40
60
0.0000 101.600
0.2530
45
20
80
0.0000 101.600
0.2540
60
20
80
0.0000 101.600

 

MM / PITCH AB
C
D
ERROR %
TPI
 0.320 50
30
60
0.0000
84.667
 0.320
50
40
80
0.0000
84.667
 0.32060
30
50
0.000084.667
 0.320
80
40
50
0.000084.667
 0.33050
20
60
0.000084.667
 0,330
60
20
50
0.000084.667
 0,340
50
20
80
0.000084.667

 

MM / PITCH AB
C
D
ERROR %
TPI
0.352050
35
60
0.0000 72.571
0.3520
60
35
50
0.0000 72.571
0.353550
20
60
0.0000 72.571
0.3535
60
20
50
0.0000 72.571

 

MM / PITCH AB
C
D
ERROR %
TPI
0.42050
40
60
0.0000 63.500
0.420
60
40
50
0.0000 63.500
0.44050
20
60
0.0000 63.500
0.440
60
20
50
0.0000 63.500

 

MM / PITCH AB
C
D
ERROR %
TPI
0.4520
5045
600.0000 56.444
0.4520
50
60
80
0.0000 56.444
0.4520
60
45
50
0.0000 56.444
0.4520
80
60
50
0.0000 56.444
0.4530
50
40
80
0.0000 56.444
0.453080
40
50
0.0000 56.444
0.45405030
80
0.0000 56.444
0.4545
50
20
60
0.0000 56.444
0.4545
60
20
50
0.0000 56.444
0.4560
50
20
80
0.0000 56.444

 

MM / PITCH AB
C
D
ERROR %
TPI
0.520ANY
ANY
60
0.0000 50.800
0.540
60
30
60
0.0000 50.800

 

MM / PITCH AB
C
D
ERROR %
TPI
0.620ANY
ANY
50
0.0000 42.333

 

MM / PITCH AB
C
D
ERROR %
TPI
0.730
4535
500.0000 36.286
0.730
50
35
45
0.0000 36.286
0.735
45
30
50
0.0000 36.286
0.735
50
30
45
0.0000 36.286
0.735
50
40
60
0.0000 36.286
0.73560
40
50
0.0000 36.286
0.74050
35
60
0.0000 36.286
0.7406035
50
0.0000 36.286

 

MM / PITCH AB
C
D
ERROR %
TPI
0.7520ANY
ANY40
0.0000 33.867
0.7530
ANYANY60
0.0000 33.867
0.7540ANYANY80
0.0000 33.867

 

MM / PITCH AB
C
D
ERROR %
TPI
0.820
45
60
50
0.000031.750
0.820
50
60
45
0.000031.750
0.820
50
80
60
0.000031.750
0.82060
80
50
0.000031.750
0.830
45
40
50
0.000031.750
0.830
50
40
45
0.000031.750
0.840
45
30
50
0.000031.750
0.840
50
30
45
0.000031.750
0.840
50
40
60
0.000031.750
0.840
60
40
50
0.000031.750
0.86045
20
50
0.000031.750
0.860
50
20
45
0.000031.750
0.880
50
20
60
0.000031.750
0.880
60
20
50
0.000031.750

 

MM / PITCH AB
C
D
ERROR %
TPI
120ANYANY30
0.0000 25.400
130
ANYANY45
0.0000 25.400
140ANYANY60
0.0000 25.400
160
45
30
60
0.0000 25.400

 

MM / PITCH AB
C
D
ERROR %
TPI
1.2550ANYANY60
0.0000 20.320
1.2540
60
50
40
0.0000 20.320

 

MM / PITCH AB
C
D
ERROR %
TPI
1.520ANYANY20
0.0000 16.933
1.540
ANYANY40
0.0000 16.933
1.580ANYANY80
0.0000 16.933

 

MM / PITCH AB
C
D
ERROR %
TPI
1.7535ANYANY30
0.0000 14.514

 

MM / PITCH AB
C
D
ERROR %
TPI
240ANYANY30
0.0000 12.700
260
ANYANY45
0.0000 12.700
280ANYANY60
0.0000 12.700

 

MM / PITCH AB
C
D
ERROR %
TPI
2.550
ANYANY30
0.0000 10.160

 

MM / PITCH AB
C
D
ERROR %
TPI
340ANYANY20
0.0000 8.467
3
60
ANYANY30
0.0000 8.467
3
80ANYANY40
0.0000 8.467

 

MM / PITCH AB
C
D
ERROR %
TPI
3.535
2060
450.0000 7.257
3.535
20
80
60
0.0000 7.257
3.535
30
80
40
0.0000 7.257
3.535
40
80
30
0.0000 7.257
3.535
45
60
20
0.0000 7.257
3.53560
80
20
0.0000 7.257
3.56020
35
45
0.0000 7.257
3.5604535
20
0.0000 7.257
3.580
20
35
60
0.0000 7.257
3.580
30
35
40
0.0000 7.257
3.580
40
35
30
0.0000 7.257

 

MM / PITCH AB
C
D
ERROR %
TPI
480ANY
ANY30
0.0000 6.350

 

MM / PITCH AB
C
D
ERROR %
TPI
4.560ANY
ANY20
0.0000 5.644

 

MM / PITCH AB
C
D
ERROR %
TPI
5
50
20
6045
0.0000 
5.080
5
50
20
80
60
0.0000 
5.080
5
50
30
80
40
0.0000 
5.080
5
50
40
80
30
0.0000 
5.080
5
50
45
60
20
0.0000 
5.080
5
50
60
80
20
0.0000 
5.080
5
60
20
50
45
0.0000 
5.080
5
60
45
50
20
0.0000 
5.080
5
80
20
50
60
0.0000 
5.080
5
80
30
50
40
0.0000 
5.080
5
80
40
50
30
0.0000 
5.080
5
80
60
50
20
0.0000 
5.080