pi?
Vernier reading is, like the slide rule, something I am just old enough to have been taught how to use, but not old enough to have ever actually used in practice.
31.34mm plus or minus 0.02mm
I get 3.138cm, if my eyes aren't playing tricks. Have my old glasses on...
3.138
In order to read the measurement readings from Vernier caliper properly, you need to remember two things before we start. For example, if a Vernier caliper output a measurement reading of 2.13 cm, this means that:
- The main scale contributes the main number(s) and one decimal place to the reading (E.g. 2.1 cm, whereby 2 is the main number and 0.1 is the one decimal place number)
- The Vernier scale contributes the second decimal place to the reading (E.g. 0.03 cm)
Let’s examine the image of the Vernier caliper readings above. We will just use a two steps method to get the measurement reading from this:
- To obtain the main scale reading: Look at the image above, 2.1 cm is to the immediate left of the zero on the Vernier scale. Hence, the main scale reading is 2.1 cm
- To obtain the Vernier scale reading: Look at the image above and look closely for an alignment of the scale lines of the main scale and Vernier scale. In the image above, the aligned line correspond to 3. Hence, the Vernier scale reading is 0.03 cm.
In order to obtain the final measurement reading, we will add the main scale reading and Vernier scale reading together. This will give 2.1 cm + 0.03 cm = 2.13 cm.
3.138"
I learned to read the vernier on a transit in 1968 and was reading one as late as about 1983.
So I have a caliper like this:
https://www.mcmaster.com/products/calipers/economy-vernier-calipers-10
that also reads MM's not because it's easy but because it's hard (JFK) and because I can.