Line Standard and End Standard of Measurement - Characteristics, Advantages and Disadvantages
What is line standard and end standard?
For accurate measurement, it is crucial to choose a suitable measuring device that suits the particular situation. There are mainly two methods for the measurement of distance. When the distance between two engraved lines is used for the measurement of length then it is called line standard or line measurement. They are used for direct length comparison, and they have no auxiliary devices. The most common line standard is the division marked meter rule.
When the distance between two parallel surfaces is used as the standard for measuring length, it is known as end standard or end measurement. The end standard is primarily used in the workshop for precision measurement. The common examples are end bars, micrometer anvil, slip gauge etc. The end parallel surface of these tools is hardened to resist wear to ensure the accuracy of measurement. Comparator is used to transfer line standard correctly to the end standard. In comparison to line standard, the end standard provides high accuracy results.
What are the characteristics of line standards - pros and cons?
Characteristics of a lime measurement are listed below
Advantages of line standards
- Quick and easy to handle, it can be used over a wide range.
- The leading ends may be subjected to wear, but marking on the scales are not subjected to wear.
Disadvantages of the line standard
- Since it does not have a built-in datum, it is difficult to align the scale with the axis of measurement.
- Since the engraved lines themselves possess thickness, it is not taken into account during measurement. So it is difficult to measure with high accuracy.
- For close tolerance length measurement, a magnifying tool may be required.
- Scales subjected to parallax effect, thereby contributing both positive and negative reading errors.
What are the characteristics of end standard - pros and cons?
Advantages of end standard
- Compared to line standard, the end standard provides a highly accurate reading.
- They are ideal for close tolerance measurement.
- Since the measuring faces are flat and parallel, the end standards possess a built-in datum, thereby making alignment of the standard with the axis of measurement is easy.
- The end of the standard is not subjected to parallax error.
- Dimensional tolerance as close as 0.0005mm can be obtained.
Disadvantages of end standard
- Only one measurement ant a time is possible, so measurement using end standard are time-consuming.
- The measuring faces of the end standard are prone to wear.
Wavelength standards: Use the wavelength of specific radiation (light source) to measure the wavelength of other spectra.