Calipers for measurement have been around for more than a century now. And today these have evolved into fully- featured digital systems for taking measurements. We can not deny the fact that the original design of a caliper was so versatile that this process of evolution required only a few changes to produce a digital caliper as we see it today. This process of the instrument evolving started with a second jaw been added in 1899. This allowed the users to take inside as well as outside measurement. Then came the vernier scales in 1951 which provided better protection. It was during the 1980s that the first digital readout of the measurement became possible which eventually brought in the ease of data collection. And today we can buy digital calipers with shop hardened electronics, improved scales that never loose their position and things like water proof digital calipers. But even today people buy digital calipers online or from the markets, and they still do it just to measure outside diameter(OD) and inside diameter (ID). Actually most of us are unaware of its versatility.
Taking Fundamental Measurements It seems pretty obvious to take easy fundamental OD, ID, depth and step measurement using calipers of all kind. But what is not very obvious is the fact that it is equally easy to take these measurements wrong. We can not deny the fact that even after great advancements in technological aspects, a digital caliper still remains an operator dependent tool. A good chance of taking incorrect measurements increases with operator applying too much force on the sliding scale, if the caliper is not placed 90 degrees to the object to be measured or maybe if the part is not placed in the middle of the jaws. Here are some tips to get the measurements accurate. For taking an outside measurement, see that you are placing the jaws over the part. This will help contact the fixed jaw in the middle of the anvil. FIt is recommended to bring small jaws, on the top of your digital caliper, to use, when taking inside measurements. Now bringing the sliding scale to “0” place the part over the jaws. You will now need to open the jaws by sliding until they are sqaurely in place making a contact with the part. In order to take depth measurements blade that extends out at the back of the instrument has to be brought into use. Now squarely place the end of the instrument onto the hole you need to measure. Check for the reading on your caliper to be zero and open the caliper until the depth rod reaches the bottom of the hole. For taking step measurements, zero the caliper and on the upper step of the part, place the sliding jaw. Then you need to open caliper jaws until you see the reference jaw contacting the lower step. Another tip. After using digital vernier calipers or calipers in general of all kinds, do not forget to repeat the process of measuring. This will ensure that the taken reading is repeatable and reliable, hence enhancing your accuracy.