It's not a difficult task to "size" pins with an everyday 0-1" micrometer; it's done all the time. A person who can't differentiate between a .0102" pin and one that's .0098" probably shouldn't be trusted to use a micrometer.
sitapaty isn't the OP.
sitapaty isn't the OP.
Your personal skill and practice is not on trial here. I can't imagine you ever mixing a few pins, nor being unable to trust your reading of a standard micrometer. Alas, many folks out there in the real world may not be as meticulous. (I am aware my eyesight is not what it was when I was thirty or even when I was sixty.) Hence the justification for a simple mistake proofing solution.
I am also aware of some manufacturers of pins who supply plus and minus pins only .0001 from nominal instead of the more common .0002.
Re: sitapathy vs. pangchiaboon
I was commenting on what I understood to be sitapathy's point about difficulty of using an instrument like a standard micrometer to differentiate mixed pins, not whether "anybody" should be able to do it. My main theme is to arrange the process to prevent mixing, NOT how to (or even whether one can) differentiate once they are mixed.