Calipers

The calipers (also caliper or vernier caliper ) is a length- measuring device.

On a bar with usually two measuring jaws A slide can be moved, which carries also measured leg. For indoor or outdoor measurement per one measurement pairs of legs is applied to a body from the outside or on the walls of a cavity inside. On slide is usually still a measuring rod, which is used eg for depth measurement of non-through holes.

History

The oldest find a caliper comes from the Greek Giglio wreck off the Italian coast, which was used for external measurement ( current name and use as a caliper ). The ship sank in the 6th century BC The lost piece was made ​​of wood. Calipers were later among the Greeks and Romans in use.

General

Today's calipers have to increase the accuracy of reading at least a vernier. Variants in which the measured value is displayed on a circular scale, are also used. Meanwhile calipers are often equipped with a digital numerical display. Although these have not a greater accuracy on, but can be read better and faster, and make the transmission of the measured values ​​to external evaluation equipment possible.

Calipers exist today preferably made ​​of stainless hardened steel to reduce corrosion and abrasion, and to ensure the dimensional accuracy permanently. For lower requirements, there are calipers made ​​of brass or plastic.

Calipers for use in mechanical engineering and metal usually have an engraved on the back table on which the integer thread diameters, the diameter of the associated core drills are compared for the preparation for cutting internal threads.

In the measurement of the outer and inner diameters with calipers in contrast to the micrometer Abbe comparator principle is not respected. The consequent error ( tilt error of the first order ) leads to a well-founded in the structure of the caliper principle unavoidable measurement uncertainty. Additional errors are guiding errors, system errors to the object to be measured and wear (damage, pollution). When measured with the depth measuring rod, the Abbe principle is not violated because scale and measuring rod are aligned.

The measurement with the vernier caliper is one of the direct methods of measurement, as input size and output size are the same ( in this case the length).

Advantages of the caliper over other length measuring devices are: • relatively high measurement accuracy, • simple and quick to use, • robust and inexpensive bags meter.

Disadvantages are: • The measurement uncertainty is larger than the display resolution. • The repeatability is worse than a meter at a constant measuring force (micrometer or dial indicator )

Designations

The Germany for technically correct term for the measuring tool described is regulated in DIN 862 and is calipers.

If the calipers a locking screw, it can also be used as an adjustable gauge. Therefore, the names caliper or vernier caliper Stir in which the instrument is often only known. Previously, the term " caliber " ( Word: calliper / caliper ) has been colloquially used mainly in southern Germany.

• Rod with fixed measuring legs ( cut shape, for external measurement ( 1) and flat parts)
• Movable slide with counter - measuring jaws (extra rod (3) for depth measurement )
• Vernier scale on the slider (metric (6 ), in ( 7) )
• Pressure lever (8 ) for releasing the spring force acting to eliminate the sliding movement

The measurement errors of a measuring slide is about between 0.01 and 0.2 mm. It depends on the measurement range, the length of the measuring arm, the wear of the slider guide and use. Higher resolution offers a micrometer screw. Here, the limit is about 1 micron.

The reading point is shifted.

To ( better the measurement tolerance ) to keep this measurement error as small as possible, it is recommended to apply no marked measuring force, the measuring arm to push together only until a slight resistance.

• " Nipper " in forestry
• Knopfmaß
• Vernier caliper with linear scale and vernier
• Workshop Calipers with linear scale and vernier
• Vernier caliper with dial gauge ( Dial caliper )
• Workshop Calipers with dial gauge ( Dial caliper )
• Digital Workshop Calipers with LCD and fine adjustment
• High Precision Digital Caliper ( capacitive measuring system )
• Precision calipers for gear teeth
• Special calipers as groove calipers, three-point calipers etc.
• Height caliper ( measuring the height of an object surface on the measuring table level)