EN
Technical drawing of the cross-section 55 degree flank angle

Bodmer thread

The Bodmer thread is a historical thread type used for mechanical and optical instruments, developed by Swiss mechanic Johann Georg Bodmer (1786-1864). The Bodmer thread is no longer used today but may be encountered in the restoration of historical mechanical or optical instruments. In such cases, suitable dies and taps can be ordered as custom-made products from us.

The Bodmer thread is a metric thread, with all dimensions and pitch specifications in mm. The flank angle of the Bodmer thread is 50°. The pitch can also be given in mm, with a variant where the number of threads per 25 mm is specified, noting that an inch corresponds to 25.4 mm. 

Thread sizes for the Bodmer thread are denoted by external diameters combined with the number of threads. There is no abbreviation for this thread type; instead, the name Bodmer is used. A size of the Bodmer thread can thus be distinctly denoted as "Bodmer 6 x 30 thread."

The Bodmer thread table includes dimensions from 3 mm to 50 mm, with pitch often identical for several sizes. The table below provides information on the external diameter, pitch in mm, and the number of threads per 25 mm. The core hole diameter is also given, which is necessary for creating an internal Bodmer thread with an appropriate core hole drilling.

To the overview thread standards
Diameter outside mm
Diameter Core hole mm
Pitch mm
Gear number to 25 mm
Taps in our online-shop
Dies in our online-shop
3,000
2,107
0,625
40
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3,500
2,607
0,625
40
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4,000
2,978
0,715
35
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4,500
3,478
0,715
35
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5,000
3,808
0,834
30
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5,500
4,308
0,834
30
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6,000
4,808
0,834
30
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7,000
5,570
1,000
25
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8,000
6,670
1,000
25
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9,000
7,213
1,250
20
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10,000
8,213
1,250
20
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11,000
9,213
1,250
20
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12,000
9,897
1,471
17
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13,000
10,897
1,471
17
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14,000
11,535
1,724
15
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15,000
12,535
1,724
15
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16,000
13,141
2,000
13
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18,000
15,141
2,000
13
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20,000
16,426
2,500
10
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22,000
18,426
2,500
10
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24,000
20,026
2,780
9
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26,000
22,026
2,780
9
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28,000
23,532
3,125
8
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30,000
25,532
3,125
8
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32,000
26,895
3,571
7
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34,000
28,895
3,571
7
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38,000
32,043
4,167
6
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42,000
36,043
4,167
6
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46,000
38,852
5,000
5
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50,000
42,852
5,000
5
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