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M eas u r i n g I n str u me n ts for L ar g e D i me n s i o n s

TESA – THE SPECIALISTS FOR LONG LENGTHS

For large dimensions from 250 mm up to several meters, TESA offers various types of mea-
suring instruments that have long proven their value in practical use.
Whatever the sizes, from a simple distance between two surfaces parallel to one another
measurement is always a challenge. Apart from the usual influences, which are proportional
to the size whilst adding to your contributions in the uncertainty budget, those due to gravity
play a key role in distortion.
Large sizes in mechanical engineering generally mean dimensions in excess of 500 mm.
Various measurement procedures are brought into play, using such items as large internal
and external micrometers with two-point contact, periphery tapes (for outside diameters),
V-bases, rotating measuring disks (rolling-contact) optical systems (triangulation with
theodolite), fixed gauges (inside caliper gauges), gauge blocks combinations or adjustable
telescopic gauges.
There are other methods that often call for very simple techniques, such as fixed gauges
(caliper gauges), combinations of gauge blocks, or even adjustable telescopic gauges.
Here's an example of a proportional relationship. With a bore of ø 1200 H7, the tolerance
area matches 0,1 mm. Reducing both values by a factor of 100 would give a manufacturing
tolerance as low as 1 μm. Of course, things are not as simple, but this example gives some
ideas about the proportions.

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