Löwenherz Thread
The Löwenherz thread is a historical thread designed by Leopold Löwenherz, a German physicist with a focus on precision instrument development and standardization, at the end of the 19th century. It took several years for the Löwenherz thread to be recognized as a standard thread at the German Mechanics Day of the German Society for Mechanics and Optics in 1893, by which time Löwenherz had already passed away.
The Löwenherz thread was used in precision mechanics, particularly in the optical industry, for about 40 years before being largely replaced by the metric thread according to DIN 13. Today, the Löwenherz thread is no longer used but may be encountered in the repair or restoration of very old components. We can manufacture corresponding dies or taps as custom-made products upon request.
The Löwenherz thread is a metric thread, with all dimensions given in mm. A peculiar feature of the Löwenherz thread is the flank angle of 53° 8′. This specification by Löwenherz was one of the points of contention that delayed the recognition of the standard for so long. At the German Mechanics Day, 60° was considered a better solution, but ultimately Löwenherz's unusual proposal prevailed. The Löwenherz thread shares the oblique flank angle with the contemporaneously developed VDI thread.
The sizes of the Löwenherz thread are distinguished by the dimensions of the external angle. The abbreviation Lh can be used for the Löwenherz thread. The thread table below contains information on the external diameter, pitch, and core hole diameter you must adhere to when working with the Löwenherz thread. The table also includes the required wrench size.