About “deg” and “mm” units for angles

In this issue, I would like to write about the units of angles used in digital levels. When you think of angle units, you probably think of degrees (°). The degree is displayed as “deg,” which is an abbreviation for ‘degree’ or “degrees. The graphic display of our digital level is set to show “°” in the factory settings. However, some customers require a “mm” display, so the display can be switched to “mm” by pressing the lower button. This “mm” display indicates “mm/m (millimeter-per-meter),” and the units used vary depending on the industry.

The display indicates how many millimeters of inclination there is in relation to 1 meter. It is not the tilt relative to the sensor size Φ50mm of our wired digital level (SELN-001B, SELN-011B) or the sensor length and width 75mm of our wireless digital level (SELN-121BM, SELN-131BM). Since this is difficult to understand in text, it is shown in Figure 1. The example below shows that the sensor is tilted by 100mm (0.1m) relative to 1m. Using the inverse trigonometric function tan^(-1), the angle is 5.71 (deg).

Then, what is the repeatability of “0.001deg”, which is a characteristic of digital levels (both wireless and wired types alike), and how many millimeters is it in relation to 1 meter? The answer is 17.5μm, or 0.0175mm. μ (micro) is 10 to the minus sixth power, and is so small that it is impossible to visually check the inclination. This means that it is smaller than the thickness of a hair. You may have some idea of the degree of accuracy.

　Fig.1 Calculation formula.

Figure 2 shows a conversion table of angle (degree) and length (mm/m) for the angle units “deg” and “mm. Please make use of this table as it may be necessary depending on the site of use.

Fig2. Angle convention table

Figure 2 shows a conversion table of angle (degree) and length (mm/m) for the angle units “deg” and “mm. Please make use of this table as it may be necessary depending on the site of use. We hope you enjoyed this article on angle units. Our digital levels (SELN-001B, SELN-011B, SELN-121BM, and SELN-131BM) can easily switch between degree (°) and millipermeter (mm/m), which is very convenient. Our development department is always looking forward to hearing from our customers who would like to have such a function, or who think it would be useful. See you soon!