Sub-machine
A mechanical or opto-mechanical machine tool that is used to produce precise graduations for measuring instruments is referred to as a sub - machine or dividing machine .
There are two types of sub-machines. Length dividing machines are used to make accurate gauges (which will be covered in this article) while circle dividing machines are used to make pitch circles for angle measurements . Both linear scales and pitch circles are important components of a wide variety of measuring instruments and must therefore be precisely manufactured and easy to read .
Length dividing machines
Length dividing machines have the task of providing that rod-shaped component of an instrument on which the length measurement is made with an exact line graduation . For this purpose, the rod is periodically moved a fixed short distance, whereupon a fixed ripper or photomechanical apparatus applies a defined line.
Essentially, a given standard dimension is transferred to another object (the length scale to be produced). In some special cases, a given length has to be divided into a number of equal parts.
Length dividing machines are required for the production of rulers of all kinds, scales on mathematical and meteorological instruments ( proportions , measuring triangles, barometers and thermometers ), but also for special measuring instruments such as coordinateographs or photogrammetric evaluation devices .
Working principle
In the dividing machines for exact scales developed towards the end of the 19th century, the step sizes to be precisely defined were taken from the template (the standard dimension) integrated into the machine. Around 1850 diffraction gratings were produced with very finely working sub-machines . The physicist Friedrich Nobert was a leader in this technology . The positioned tool head scratches the graduation marks in the metal or glass scale to be produced . The setting of the normal position was initially carried out with a strong magnifying glass , later with our own reading microscope . In the 1960s, the optical and geodetic industry (e.g. at Kern Aarau ) began to no longer scratch the graduation lines, but to produce them photo-mechanically.
After Meyers Encyclopedia 1888 its length dividing machine worked as follows (somewhat shortened):
On a carefully prepared steel screw , with its two smooth [provided with no threaded] ends in fixed bearings by means of a crank around its longitudinal axis is rotatable, the shift Reißer plant , ie the device which scratches the graduation marks in the object to be divided and, attached to a carriage, is moved forward with this in a very uniform manner. A pointer rotating with the spindle indicates small fractions of a spindle rotation on a side disk. Due to their very low pitch, 1 mm can be divided into 3000 and more perfectly equal parts and scratched into glass with the diamond , as is necessary for experiments on diffraction of light.