How to Use a Digital Caliper- the "Zero" button features.

All digital calipers come with "zero" or "origin" button for zeroing the display. This can be done at any point along the slide just by pressing the button. Normally, the zero point is set where the two outside jaws faces are touched with each other. You can also set the zero point at any point along the slide to perform the differential measurement. Below are 3 out of many examples on how a digital caliper can perform measurement by zeroing the display :

1. Measuring the difference in size between objects.

Let say you bought 20 pieces of screws for your assembly project. You need screws with length 6mm or less. The depth of the tapped hole for the screw seems to be very tight, if the screw a bit longer than 6 mm, the screw will not screwed in completely. So you need to measure the length for every piece of the screws you bought before assembling. First, make sure the digital caliper display shows "zero" when you close the jaws completely. Then, pull the jaw so that the digital display shows 6.00 mm.




At this point, push the zero button. The digital display will now shows 0.00 mm.





Now you can measure each of the screws. The display will show the difference of the screw length compare to the dimension you need which is 6mm. Since you need the screw with the same length or shorter, you can only take screws with the display show zero or minus number reading.


The display with plus number reading means the screw is longer than 6 mm. It is also easier to identify how much longer or shorter the screw by using this method.


2. Measuring the center-to-center (pitch) of 2 or more equal size holes.


It will be easier to measure the pitch of the 2 or more equal size holes using a digital caliper. Make sure the holes are the same size by measuring the holes using the internal jaws of the digital caliper. Let say all the holes diameter are measured 6.96 mm.





While measuring one of the hole diameter, when the digital display shows 6.96 mm, hold your thumb lightly, then push the "zero" button. The display will show 0.00 mm.







Then you can use the internal jaws of the digital caliper again to measure the pitch of the 2 holes as shown on the picture. The digital display will show the pitch or center-to-center distance between the 2 holes.




3. Measuring the depth of a small hole.

To measure hole depth, we need to use a digital caliper with probe which attached to the movable head. What if the hole diameter is smaller than the probe? You can not fit in the probe into the hole to measure the depth. What you can do is to find a pin which can fit into the hole to the bottom, and the pin is longer than the hole depth. The pin should not be to loose when fitted into the hole or you may not get accurate measurement. Fit in the pin until the bottom of the hole.


Measure the length of the outside portion of the pin. At that point, set the digital caliper display to zero.


Pull out the pin from the hole. Then measure the overall length of the pin. The digital caliper display will show the dimension of the hole depth.

In this case, the hole depth is 9.62 mm.