Calipers
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About the Caliper topic
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What is a caliper?
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Vernier, clock or digital display: Three versions of gauge reading
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Advantages and disadvantages of the read-out variants at a glance
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Read the caliper
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Caliper for different applications
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What do I have to pay attention to when using a measuring slide?
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Caliper or slide gauge: What is the correct name?
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FAQs: The most common questions about slide valves
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Conclusion: This is how you can find the right caliper
What is a caliper?
A sliding caliper is a precise measuring device with which different measurements can be taken. Thanks to its two movable measuring legs each, a sliding caliper can take internal and external dimensions and, with its depth measuring rod, for example, determine the depth of a hole. Due to its variable application possibilities, it is one of the most commonly used measuring tools. There are analogueue and digital calipers as well as special versions for special applications.
Vernier, clock or digital display: Three versions of gauge reading
Vernier caliper
The vernier is a movable length scale that allows measurements to be made that are accurate to a millimeter fraction. Reading, however, requires some practice, attention and a certain amount of arithmetic. A good eye is also required to be able to recognize the small scale at the sliding caliper correctly. The great advantage of the classic vernier caliper is that it is robust. Monobloc calipers made of stainless steel have an extremely long service life with good care. And even cheaper carbon steel chrome-plated calipers can provide good service for decades. Spray and jet water cannot touch the measuring devices.
Clock caliper
The clock caliper – or also the dial gauge with a round scale – also works analogueue and provides reliable measurement results with the correct application and maintenance of the highest precision. Thanks to the clock face, it is easier to read than the vernier caliper. Another advantage is the lock wheel, with which the dial gauge can be set to zero at any point, so that differential measurements are possible without any problem. It should be noted that due to its structure of gears and rods, the dial caliper is a little more susceptible to dirt and dust than the vernier caliper. Good care and careful storage are therefore a duty here.
The digital caliper
Digital calipers are now standard in many areas. While they do not measure more accurately than analogue models, they make it much easier to read the results. Parallax and other reading errors are avoided. As with the watch caliper, the zero position is also possible in any position with the digital caliper. Thanks to the ABS function (absolute function), the last zero position can even be saved when the device is switched off. In addition, other amenities include: Measurements can be saved, units can be easily changed from metric (cm) to Anglo-American (inch) systems. Another great advantage is that the measurement data can be read out via an interface and processed directly on the computer. This saves time and effort for manual transfer and makes it easier, for example, to create statistics for quality assurance. One disadvantage is the dependence of the devices on the power supply, so that new batteries should always be in stock. In addition, digital calipers are slightly more susceptible to damage (fall, water) and tend to have a shorter service life – although this can still be more than 10 years.
Advantages and disadvantages of the read-out variants at a glance
| High measurement accuracy | Comfortable reading | Durability / robustness / water resistance | Flexible zero setting possible | Storage of measured data or zero position | Independant of power supply | Easy conversion of measurement units | Direct transfer of measurement data to computer | |
| Vernier caliper | +++ | - | +++ | - | - | +++ | - | - |
| Dial caliper | +++ | ++ | ++ | +++ | - | +++ | - | - |
| Digital caliper | +++ | +++ | - | +++ | +++ | - | +++ | +++ |
Read the caliper
With a digital sliding caliper, a quick glance at the display is enough to know the measured value. The measured value is also very easy to read with a watch caliper. Only with a vernier caliper with a movable length scale one has to look more closely in order to be able to read the exact measured value.
Most vernier calipers offer two different scales for reading the measurement. The lower scale shows the value in centimeters and the upper scale shows the measured value in inches or inches. The relevant reading marks for both scales are the "0" on the movable part of the measuring slider.
Read the measured value in centimeters
In the adjacent example, the reading mark "0" on the lower scale is between the tick marks for 3 mm and 4 mm. So the measured value lies somewhere between 3 and 4 mm.
In order to determine the exact value, you have to look further to the right on the lower scale. At the first moment, the numerical values are not considered, but only the tick marks. Because you have to find a division in the lower scale, which is exactly below a division in the upper scale. It does not matter which division of the upper scale this is. In our example image, the division between 5 and 6 is identical to a line in the upper scale (see red marking). So the caliper shows a value of 3.55 mm.
Read the measured value in inches
The upper scale is read in the same way. However, each division corresponds to the fixed scale 1/16". The "0" of the sliding scale is 2/16" after the tick. In the upper scale, the division of the value "2" corresponds to a division of the lower scale (see blue marking). So there are 2/16" or 16/128" added to the list. The measured value is therefore 18/128" or 9/64", which results in the equivalent of 3.571 mm.
Caliper for different applications
Pocket slide gauge;
Handy caliper for DIY needs
Workshop caliper:
Professional sliding caliper for use in the workshop, usually standardized according to DIN 862
Depth gauge
Special sliding caliper for depth measurement, e.g. for steps, grooves or holes
Crimp caliper:
Caliper for exact measurement of crimp height and crimp width
Brake disc caliper:
Special caliper to measure brake disc wear safely and correctly
What do I have to pay attention to when using a measuring slide?
- The measuring surfaces should be free of burrs, dry and clean
- Always measure as close to the ruler as possible
- Make sure that the light conditions are good when reading
- Application takes place without force - do not falsify the measurements by unnecessary force
- Observe the reference temperature of 20° C.
Our practical tip
A common error when measuring with measuring sliders is that the tool is not created correctly. Make sure that the workpiece is not measured with the ends of the legs, but that it is always inserted up to the middle of the jaws. This prevents fluctuations in measured values.
Caliper or slide gauge: What is the correct name?
According to DIN 862, the technically correct designation in Germany is "sliding caliper". Nevertheless, the terms “sliding gauge” or “sliding gauge” are still widely used – the latter is mainly used in Austria. This can be explained by the fact that a sliding caliper with locking screw can also be used as a "gauge". The term “caliber” can also be found here and there, especially in southern Germany.
FAQs: The most common questions about slide valves
Digital or analogue: Which caliper is right for me?
This is mainly your personal preference when it comes to reading. The exact display on the digital caliper facilitates the work, whereby the analogueue models with robustness and independence from current points.
Are digital calipers as accurate as analogue with vernier?
Yes, the accuracy of the digital models is no longer inferior to the analogueue of the same quality.
How much money should I spend?
Depending on what your caliper is to meet, high-precision tools for professional use are, of course, more expensive than simple DIY designs.
Simpler, good quality sliding calipers are usually sufficient for measuring in the wood field, as material-related fluctuations can be expected here anyway. Even for occasional measurement in the metal environment, you do not need a professional workshop caliper for DIY. You should still attach importance to quality, because the processing of the tool is decisive for the measuring accuracy.
Conclusion: This is how you can find the right caliper
Basically, you should ask yourself the question:
What purpose does my caliper have to fulfill: Do I need a practical all-rounder for use at home or a high-precision tool for professional use – perhaps even in a special area? Under what conditions do I use the device and how do I deal with battery consumption?
The next question is: How precise must the measurements be? And what is more important, a reliable measurement on a nanometer or a comfortable and fast application? The answers will gradually make you the ideal caliper for your needs – and your budget.