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Informations: Movement Sizes
Conversion beween Measurement Sytems

Paris Ligne

Still a common specification for movement diameters, although they are dimensioned since long in mm (millimeters).

The idea was to specify the monting diameter matching the aperture in the case. So this diameter should be a bit smaller than the specified size in lignes, and the mounting flange should be reasonabliy bigger, to prevent that the movement falls through the case.

Unfortunately many  data sheet specifications are simple lies, making them useless. Big movements were specified bigger than actual, and it could happen that a movement fell through the case with the according mounting diameter. And the competition for the smallest movement made many appear substantially smaller on papers than in reality.

1''' (ligne) = 2.2558291mm
1''' (ligne) = 0.088812168" (inch)
Size after Lancashire gauge

Mainly  used by U.S. manufacturers, but all over the world manufacturers made movements matching this system.

The Lancashire gauge demonstates how a good idea, the standardization of movements, can be spoiled so far that the same movement appeared with different sizes in different catalogs. The rules to determine the size were not uniform, and moreover changed with the time.

The most common but still crazy system is as follows:
1) Base is 0 size = 1" (inch) diameter, and each step up adds 1/30".
2) 5/30" was added for the mounting flange, except sizes over 16 size, in which case 6/30" was added until about 1910.
3) After about 1910, uniformly 5/30" was added for the mounting flange.
4) Unfortunally it was not common to make the flange as wide as mentioned above, but for many movements it was applied.
5) When movements became smaller than 0 size, first notations like 00 size, 000 size, with a 0 for every step down. But this became soon awkward.
6) So the steps down got the notations 2/0 size, 3/0 size, 4/0 size etc, starting with 2/0 size (equivalent to 00 size) for the first step down.
Dennison code

Created by Aaron Dennison, and used by the case manufacturer Dennison

Set of mounting diameters (case apertures) optimally covering the common sizes after Lancashire gauge and in Paris lignes.

Base is the size A with an aperture of one inch diameter, and the following sizes have 1/16 inch increment.
To OverviewTo Overview
.
Lignes
 '''

mm

Inches
Size

Denn-
ison

1 2.26 0.0890



2.54 0.1000
33/0
1.25 2.82 0.1110


1.5 3.38 0.1332



3.39 0.1333 32/0
1.75 3.95 0.1554



4.23 0.1667
31/0
2 4.51 0.1776


2.25 5.08 0.2000
30/0
2.5 5.64 0.2220



5.93 0.2333
29/0
2.75 6.20 0.2442


3 6.77 0.2664
28/0
3.25 7.33 0.2886



7.62 0.3000
27/0
3.5 7.90 0.3108


3.75 8.46 0.3330



8.47 0.3333
26/0
4 9.02 0.3552



9.31 0.3667
25/0
4.25 9.59 0.3775


4.5 10.15 0.3997



10.16 0.4000
24/0
4.75 10.72 0.4219



11.01 0.4333
23/0
5 11.28 0.4441


5.25 11.84 0.4663



11.85 0.4667
22/0
5.5 12.41 0.4885



12.70 0.5000
21/0
5.75 12.97 0.5107


6 13.53 0.5329



13.55 0.5333
20/0
6.25 14.10 0.5551



14.39 0.5667
19/0
6.5 14.66 0.5773


6.75 15.23 0.5995



15.24 0.6000
18/0
7 15.79 0.6217



16.09 0.6333
17/0
7.25 16.35 0.6439


7.5 16.92 0.6661



16.93 0.6667
16/0
7.75 17.48 0.6883



17.78 0.7000
15/0
8 18.05 0.7105


8.25 18.61 0.7327



18.63 0.7333
14/0
8.5 19.17 0.7549



19.47 0.7667
13/0
8.75 19.74 0.7771


9 20.30 0.7993



20.32 0.8000
12/0
9.25 20.87 0.8215



21.17 8.8333
11/0
9.5 21.43 0.8437


9.75 21.99 0.8659



Lignes
 '''
mm

Inches Size

Denn-
ison


22.01 0.8667
10/0
10 22.56 0.8881



22.86 0.9000
9/0
10.25 23.12 0.9103


10.5 23.69 0.9325



23.71 0.9333
8/0
10.75 24.25 0.9547



24.55 0.9667
7/0
11 24.81 0.9769


11.25 25.38 0.9991



25.4 1.0000
6/0 A
11.5 25.94 1.0213



26.25 1.0333
5/0
11.75 26.51 1.0435



26.99
1.0625

B
12 27.07 1.0657



27.09 1.0667
4/0
12.25 27.63 1.0879



27.94 1.1000
3/0
12.5 28.20 1.1102



28.58
1.1250

C
12.75 28.76 1.1324



28.79 1.1333
2/0
13 29.33 1.1546



29.63 1.1667
0

13.25 29.89 1.1768



30.16
1.1875

D
13.5 30.45 1.1990



30.48 1.2000
1
13.75 31.02 1.2211



31.33 1.2333
2
14 31.58 1.2434



31.75
1.2500

E
14.25 32.15 1.2656



32.17 1.2667
3
14.5 32.71 1.2878



33.02 1.3000
4
14.75 33.27 1.3100



33.34
1.3125

F
15 33.84 1.3322



33.87 1.3333
5
15.25 34.40 1.3544



34.71 1.3667
6
15.5 34.97 1.3775

G
15.75 35.53 1.3988



35.56 1.4000
7
16 36.09 1.4210



36.41 1.4333
8

36.51
1.4375

H
16.25 36.66 1.4432


16.5 37.22 1.4654



37.25 1.4667
9
16.75 37.79 1.4876



38.10 1.5000
10 I
17 38.35 1.5098


17.25 38.91 1.5320



38.95 1.5333
11
Lignes
 '''
mm

Inches Size
(1910+)

Denn-
ison
17.5 39.48 1.5542



39.69
1.5625

J

39.79 1.5667
12
17.75 40.04 1.5764


18 40.60 1.5986



40.64 1.6000
13
18.25 41.17 1.6208



41.28
1.6250

K

41.49 1.6333
14
18.5 41.73 1.6430


18.75 42.30 1.6652



42.33 1.6667
15
19 42.86 1.6875

L

43.18 1.7000
16
19.25 43.42 1.7096


19.5 43.99 1.7318



44.03 1.7333
(17)


44.45
1.7500

M
19.75 44.55 1.7540



44.87 1.7667
17 (18)

20 45.12 1.7762


20.25 45.68 1.7984



45.72 1.8000
18 (19)

46.04
1.8125

N
20.5 46.24 1.8206



46.57 1.8333
19 (20)

20.75 46.81 1.8429



47.41 1.8667
20 (21)

21 47.37 1.8651



47.63
1.8750

O
21.25 47.94 1.8873



48.26 1.9000
21 (22)

21.5 48.50 1.9095


21.75 49.06 1.9317



49.11 1.9333
22 (23)


49.21
1.9375

P
22 49.63 1.9539



49.95 1.9667
23 (24)

22.25 50.19 1.9761


22.5 50.76 1.9983



50.8 2.0000
24 (25)

22.75 51.32 2.0205



51.65 2.0333
25 (26)

23 51.88 2.0427


23.25 52.45 2.0649



52.49 2.0667
26 (27)

23.5 53.01 2.0871



53.34 2.1000
27 (28)

23.75 53.58 2.1093


24 54.14 2.1315



54.19 2.1333
28 (29)

24.25 54.70 2.1537



55.03 2.1667
29 (30)

24.5 55.27 2.1759


24.75 55.83 2.1981



55.88 2.2000
30 (31)
25 56.40 2.2203






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Last update:  01-22-2020