A screw thread system devised by a commission of instrument makers, government agencies and technical societies, and introduced in Berlin in 1894. In 1888 the Verein Deutscher Ingenieure had introduced a thread series covering diameters from 6 millimeters to 40 millimeters. The new series adopted the same thread form but extended it down to 1 mm; the 6 - 10 mm sizes are identical to the earlier series. It was used in instruments made in Germany and Austria and to some extent France in the late 19ᵗʰ – early 20ᵗʰ century.
The system is named for Dr. Leopold Löwenherz, a physicist active in metrology and especially the design of instruments, who was Director of the Physikalisch-Technische-Reichsanstalt. The designation Löwenherz thread has for a long time been applied to the whole series, not just the 1 mm to 10 mm portion.
Diameter | Pitch | Root Diameter |
Pitch diameter |
Tap drill |
---|---|---|---|---|
1.0 | 0.25 | 0.625 | 0.812 | 0.64 |
1.2 | 0.25 | 0.825 | 1.012 | 0.84 |
1.4 | 0.30 | 0.950 | 1.175 | 0.97 |
1.7 | 0.35 | 1.175 | 1.437 | 1.20 |
2.0 | 0.40 | 1.400 | 1.700 | 1.44 |
2.3 | 0.40 | 1.700 | 2.000 | 1.74 |
2.6 | 0.45 | 1.925 | 2.260 | 1.97 |
3.0 | 0.50 | 2.250 | 2.620 | 2.30 |
3.5 | 0.60 | 2.600 | 3.050 | 2.65 |
4.0 | 0.70 | 2.950 | 3.470 | 3.00 |
4.5 | 0.75 | 3.375 | 3.930 | 3.43 |
5.0 | 0.80 | 3.800 | 4.400 | 3.87 |
5.5 | 0.90 | 4.150 | 4.825 | 4.23 |
6.0 | 1.00 | 4.500 | 5.250 | 4.60 |
7.0 | 1.10 | 5.350 | 6.175 | 5.45 |
8.0 | 1.20 | 6.200 | 7.100 | 6.30 |
9.0 | 1.30 | 7.050 | 8.025 | 7.15 |
10 | 1.40 | 7.900 | 8.954 | 8.00 |
12 | 1.60 | 9.600 | 10.800 | 9.70 |
14 | 1.80 | 11.300 | 12.650 | 11.40 |
16 | 2.00 | 13.000 | 14.500 | 13.10 |
18 | 2.20 | 14.700 | 16.350 | 14.82 |
20 | 2.40 | 16.400 | 18.200 | 16.52 |
22 | 2.80 | 17.800 | 19.900 | 17.93 |
24 | 2.80 | 19.800 | 21.900 | 19.93 |
26 | 3.20 | 21.200 | 23.600 | 21.35 |
28 | 3.20 | 23.200 | 25.600 | 23.35 |
30 | 3.60 | 24.600 | 27.300 | 24.75 |
32 | 3.60 | |||
36 | 4.00 | |||
40 | 4.40 |
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Last revised: 18 January 2011.