Then you should note the number of divisions on the slide Vernier from the 0 to a line which exactly coincides with a line on the bar.įor instance, the Vernier plate has been moved to the right one and four tenths and one twentieth inches (1.450), as shown on the bar and the fourteenth line on the slide Vernier exactly coincides with a line, as indicated on the illustration above. 050) the 0 mark on the slide Vernier is from the 0 mark on the bar. When you read the tool, you should note how many inches, tenths (or. The difference will continue to increase 1/1000 of an inch for each division until the 50 on the Vernier coincides with the line 49 on the steel rule. If the tool is set so that the 0 line on the Vernier plate coincides with the 0 line on the bar, the line to the right of the 0 on the Vernier plate will differ from the line to the right of the 0 on the bar Pg. The difference between the width of one of the fifty spaces on the Vernier plate and one of the forty-nine spaces on the bar is therefore 1/1000 of an inch (1/50 of 1/20). 45, 50.The fifty divisions on the Vernier plate occupy the same space as forty-nine divisions on the bar. The Vernier plate is divided into fifty parts and numbered 0, 5,10,15, 20, 25. Every second division represents a tenth of an inch and is numbered. For the vernier calipers, the bar is graduated into twentieths of an inch (.050"). A precision of measurement of +- 0.02 mm is reached only by a few very welltrained practitioners, but this precision is independent from the use of the traditional slide gauge with a vernier scale or the digital Vernier.How to read the English version of vernier calipers correctly? Here are some useful tips. This error might be higher than the value on the vernier scale. It is important to mention however that measuring errors appear by holding the moving jaw tilted out of parallel with the fixed jaw either through force or lack of straightness in the reference edge of the beam or through deformation of the material of the instrument itself by age, temperature or wrong use. For this reason a high quality digital instrument instead of a slide gauge is much easier to read because of the LCD display. The precision of measurement is impressing here, but with the normal human eye a limit is reached here by just being able to read these intricacies without special lenses. Three gauge marks on a 1:50 ratio vernier scale would give 3x 0.02 mm= 0.06 mm. In this case 3 gauge marks on the vernier scale add to the sum of 3x 0.05 mm= 0.15 mm. You only have to consider that in case of a vernier scale with the ratio 1:20 the measured value is a multiple of 0.05 mm which is shown with a distance of 3 gauge marks. The basic principle of measuring stays always the same. A vernier scale of the ratio 1:20 has 20 gauge marks in a distance of 0.95 mm, a vernier scale of the ratio of 1:50 has 50 gauge marks with a distance of 0.98 mm from mark to mark. The vernier scale doesn’t relate always to a ratio of 1:10 of the main scale. So the result is 23 mm plus 0.6 mm = 23.6 mm It is 0.6 mm referring to a 1/10 vernier scale and has to be added to the mm value you just found on the main scale. This value – in our example here 6 – is the value figuring behind the dot. To find out this value you have to find the value on the vernier scale - exactly opposing the gauge mark for a mm on the main scale. Just like a magnifying lens this helpful tool allows to define the exact value of the split mm. In this case the vernier scale is very helpful. The precise value of this split fraction of a mm cannot be defined precisely on the main scale because the measuring unit is just too small. In our present example this is 23 mm and some very small split portion of a millimeter. You just take the value opposing the value O of the vernier scale. To define a value on the main scale is easy. The large main scale runs over the whole length of the caliper and under this main scale a second scale which is shorter and called vernier scale. If you look at the slide gauge, you will see two different scales.
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