Firstly, I'm sorry that my english is not good.
I would like to post an article regarding indicators calibration

Newly purchased indicators or after a period of use should be calibrated.

The calibration performed

Check out.
Technical inspection and measuring force
Check measurement: check total errors, component errors and error recovery; repeatability test.

Environmental conditions

When performing the calibration, the following conditions must be met:

For comparison meters with a value of 0,001 mm; 0.002 mm:
+ Temperature: (20 ± 3) oC;

+ Humidity: (50 ± 15)% RH.

For a meter with a value of 0.01 mm:
+ Temperature: (20 ± 8) oC;

+ Humidity: (50 ± 20)% RH.

Calibration Device Clock So

Gauge Blocks.
Pillar heaps of lakes.
Force measuring device with division value ? 0.02 N or scale meter with division value ? 2 g

For more details, please refer to this article: https://www.techmaster.com.vn/blogs/...uan-dong-ho-so (sorry it's not translated into English yet)