On a Creality CR-10 Max, there is a bag of unidentified spares, which include three unmarked nozzles.
There is a needle that is exactly 0.4 mm in diameter, which needle fits exactly inside one of nozzles. It also fits loosely in the largest nozzle, which diameter looks like it's really close to 0.8 mm on my digital caliper. The smallest one has only room for the tip of the needle, and the digital caliper reads 0.34 mm on the tip of the needle when pushed from the inside of the nozzle.
I assume the sizes are: 0.8 mm, 0.4 mm and 0.3 mm.
Can you tell me how to measure the diameter with better accuracy?