Vernier Calipers fall under the category of high precision measuring instruments meaning they provide measurements very precise in nature often accurate to the hundredth of a millimeter. This accuracy is achieved by the use of a vernier scale attached to a main scale which makes the vernier caliper different from other calipers.
This highly sensitive nature also makes it necessary for the vernier caliper to be constantly maintained and calibrated as even the slightest distortion in its settings could have an effect on the accuracy of the readings. Below we will provide the method for vernier caliper calibration and some standard Vernier caliper calibration procedures.
- First and foremost, the caliper’s jaws which are the parts responsible for measuring distances should be cleaned to make sure they are free of any dirt or grease.
- The gear should be moved back and forth to make sure that it is moving without any hindrance.
- Next comes the zero reading check. Bring the jaws in contact with each other and check the reading on the dial. It should be zero. If this is not the case then set it manually to zero.
- Insert a 0.500 inch (12.7 mm) standard gauge block between the jaws used to measure outer diameters. Both the jaws should be in contact with the block but do not press the jaws too tightly on the surface. Record the reading accurate to 3 decimal places. Take at least three readings to eliminate any inconsistency while measuring.
- Step 4 should be repeated with a 1 inch (25.4 mm) gauge block and afterwards with a 4 inch (101.6 mm) block. Note the readings.
- The same procedure may be carried out using micrometer standards as well which are of 0.150, 0.200 or 0.300 inches. Record and compare these readings as before.
- To calibrate the internal jaws, set them to 0.500 inch (12.7 mm) and use the locking screw to fix their position. Then use another calibrated vernier caliper to measure the distance between the jaws. Record the readings and compare. Take multiple readings for more accuracy.
- Repeat step 7 setting the jaw position at 25.4 mm and 101.6 mm sequentially. Observe and record the readings.
- Now to calibrate the height measurement, set a 12.7 mm gauge block on a flat surface. Place the caliper vertically so that its bottom flat surface rests on top of the gauge block. Now extend the depth measuring stick using the thumb screw so that it touches the ground and note the reading.
- Repeat the step using the 25.4 mm and 101.6 mm gauge blocks. Similarly use the micrometer standards to obtain another set of readings.