Calipers are amazing little precision measurement tools. They provide four distinct ways to measure, each with incredible utility—inside diameter, outside diameter, depth, and step. Any and all calipers are capable of each of these measurements, whether an electronic, dial, or Vernier caliper. We will walk you through each of these measurement techniques, so that you are well-versed in the capabilities of your caliper.
A basic caliper is made of 7 different parts. These include: upper jaws, lower jaws, lock screw, thumb screw, Vernier scale, main scale, and depth rod. Depending on whether your caliper is manual or digital, you may have a readout screen that tells you a particular measurement or you might need to rely on the displayed scales to read a measurement. Both the upper and lower jaw sets consist of one fixed jaw and one sliding jaw that is adjustable for measurement purposes. An important step before completing any measurement is to ensure that your caliper is set to a zero point. If your tool is even the slightest bit off from the zero point, your final measurement will be inaccurate. In order to do this, open the jaws, clean them thoroughly, and close them again. At this point the readout should be 0.00. With an electronic caliper, you may have to reset the zero button.
Let’s start with outside measurement. The simplest of all the caliper measurements, outside measurement involves measuring the outside surface of an object. Take the object you need to measure, open the lower jaws of the caliper, and then close the jaws gently around the object. Then just read the measurement from the digital screen or on the manual scale. Remember to make sure your caliper is perpendicular to the object you are measuring, and that there is no dirt or residue on the jaws that could invalidate the measurement. The second type of measurement is inside measurement. For inside measurement, you will use the upper, smaller jaws of your caliper. Start by closing the upper jaws and placing them into whatever space you are measuring. Then, slowly open the jaws until they are pressed against the edge of the inside surface. Once the jaws are pressed again the edge of the space, you can read off the measurement you were looking for. Again, make sure that the caliper is properly lined up with the object.
The third type of measurement you can accomplish with a caliper is called depth measurement. Depth measurement is used for determining the size of a particular hole and for this purpose you will use the depth rod at the end of the caliper. Simply put the machined end of your caliper at the top of the hole you are measuring and extent the depth rod until it makes contact with the bottom of the hole. Read off the measurement, and you are done. Double check that you are holding the caliper parallel to the hole you are measuring, as any off angle could give you a false measurement. Finally, the fourth type of caliper measurement is a step measurement. A slightly more complex and lesser known technique, step measurement can be very useful. Start by placing the sliding jaw of the caliper on the upper step of the object you are measuring, with the caliper just slightly open. Slowly begin to open the caliper further until the fixed jaw hits against the lower step of the object. Then read off the measurement and voila!
Calipers are a necessary tool for any successful precision measurement toolbox. These handy little devices are capable of four separate measurements, each with distinct utility. Calipers can be used to conduct outside diameter, inside diameter, depth, and step measurements. Depending on the types of measurements you regularly do, you may use one or two of these more than others. However, having an understanding of all the measurement tricks of a caliper will help you be equipped to handle any measurement need.