What are calipers?
Calipers are a ruled scale, dial, or digital method to measure dimensions of an object via two adjustable jaws.
Inside calipers measure the internal size of an object, and outside calipers measure the external size of an object. For example, inside calipers may be utilized to measure the inside of a cylindrical ring gage, while outside calipers could be used to measure the diameter of a master disc.
There is a fixed, main scale with a sliding readout that moves across the main scale. This sliding readout is typically moved with a thumb slider and can be set in place via a set screw.
The three main types of calipers are vernier, dial, and digital. They are comprised of four main parts: the outside jaws, the inside jaws, the main scale, and the measurement method.
How are calipers used?
For our purposes here, we will focus on dial and digital calipers.
First, you must zero your caliper. For dial calipers, you use the thumb slider and close the caliper jaws fully using the thumb slider until no light can pass through where they meet. If the dial does not read zero, loosen the lock screw, turn the dial face until the needle points to zero, and tighten the lock screw. For digital calipers, again, close the caliper jaws fully using the thumb slider until no light can pass through where they meet. If zero is not displayed on the digital readout, press the zero button on the digital readout. You have successfully zeroed your dial or digital calipers.
Next, we will discuss an outside measurement. Open the outside caliper jaws via the thumb slider so that the opening is slightly larger than the outer edges of the object you are measuring. Place the outside caliper jaws on either side of the object and close the outside caliper jaws in on the object using the thumb slider. Be careful! You do not want to over tighten the caliper jaws. They should fit snugly around the item without causing damage to the item under test or the outside caliper jaws themselves.
Then there are inside measurements. To take an inside measurement, begin with the inside caliper jaws fully closed. Insert the inside caliper jaws into the object under test. Slowly use the thumb slider to open the inside caliper jaws until they touch each side of the object under test. Be careful! They should fit snugly inside the item without causing damage to the item under test or the inside caliper jaws themselves.
How do we read dial or digital calipers?
Dial calipers are read by finding the largest visible measurement on the main scale and adding the measurement from the dial face. Be sure to pay attention to the scale on the dial face. Dial calipers will only be available in imperial or metric measurements. You will not have the option to switch between the two as you would on most digital calipers.
Digital calipers are read simply by looking at the numbers displayed on the digital readout. Ensure you have the correct type of measurement selected, imperial or metric, on the digital readout.
Calibration and Sales

F. D. Hurka Metrology offers calibration services on and sales of all calipers. Please contact us at sales@fdhurka.com or 704-552-0008 for more information.

By / Published On: October 17th, 2022 / Categories: Calibration /

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