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# Virtual Graduated Ruler – Simulator of Use and Reading of Line Gauge in Millimeter

`interact with the simulator of ruler, line gauge or scale 1:100 in millimeter`

## How to use the ruler or line gauge

By definition, a ruler is a ‘straight edge tool, designed to draw straight lines’, and in metrology, scale is the ‘ordered set of marks, associated with any numbering, which is part of a metering device’. By uses and customs, it is common in metal-mechanical workshops to refer to ‘graduated rules’ as scales. At times, this page will follow this culture.

The simple and efficient geometry of the scales allows this instrument to be found in several professional environments, for example: in the metal-mechanic workshops; engineering; on the desks or drawing boards of various professionals; in classrooms of technical drawing, geometry, mathematics among several others. The application of the concept of ‘graduated ruler’ is also found with variations, for example: the so-called ‘carpenter’s meter’ -animation 1- which is a relatively long rigid ruler-two meters, for example- graduated, segmented and articulated Can be folded to fit in a toolbox or drawer; The tape being a flexible steel tape with the engraved scale in the ink on one of its faces which can coil in a drum and retract in a box that fits in the pocket, for example; The ‘measuring tape’ measuring instrument of tailors and seamstresses, in it the graduation applied to a cloth tape; And so on. The scales can be found in stainless steel, wood, plastic, acrylic, fabric, sometimes the graduation is engraved from right to left, in endless variations.

The scale represented in this simulator is 1: 100 – this means that the numbering recorded on the ruler represents the hundredth part of the meter, or centimeter. The centimeter is subdivided by ten, this means that each mark of the measuring instrument corresponds to one millimeter that is the thousandth part of the meter.

figure 1 – one use of the scale

The scale (instrument) of this simulator is suitable for measurement because, unlike the ruler used to draw in the drawing classes, the zero mark coincides with the top, allowing the measurement of recesses or heights with relative accuracy. Layout causes a problem. Over the years the tip of the scale wears out and the measurements become less precise. It is therefore recommended that we use some mark, for example: in figure 2 a of the ten millimeters as zero and subtract this value from the taken, to obtain the Measurement of the ‘object of measurement’:

figure 2- measure with one scale (measurement instrument) or graduated ruler

Observe in the simulator that you can not be sure how much the edge of the measurand is between the marks. This simulator indicates this fact by placing a number five in parentheses (5). Technological devices like the vernier correct this limitation.

Observe also that it is not possible to be sure when the mark is aligned with the border of the mesuring in both sides. This lack of precision of reading has as consequence that the measure taken is less trustful or not precise. Instruments as the vernier caliper corrects this limitation.

al ruler or line gauge: practice of use, interpretation in millimeter

##### Eduardo Stefanelli

Engenheiro por profissão, professor por vocação