As something of a lurker in this group and maybe an old timer who should be ignored I am often surprised by the constant search for accuracy in terms of numbers.
A simple lathe such as the Portass S which I have alongside my Myford ML7 is a case in point. I use it a lot making things for fishing boats and the local bus operator. No complaints from the traffic inspector. (please ignore this Greg)
I do have some digital calipers but I can never be sure which button to press or the battery has run out. I do use a vernier caliper from time to time by way of a magnifying glass.
For the most part I use firmer calipers, the type you tap.
I expect what I am trying to say is that achieving the right fit, be it running, press or other is a matter of feel or something like that. For the most part this works.
Donald South Uist