Hal, I know you knew that you got it.
Have got to agree with what you said about grandkids. No one is taught the basics of living, cooking ,sewing, repairing, gardening, etc. and living without electricity and computers these days. Unless it moves on a screen or comes out of a box from a store, and food that you can stick in a micowave most people would not no how to survive.
No wonder tradespeople ask $100 or more an hour to fix something, because they can, and if its made in China, throw it away and buy another because it costs too much to repair. Again, no wonder the world is in such a mess with the constant disposal of manufactured junk for the purpose of making the almighty dollar. Getting off the soap box here now and back to the main thread.
Interesting stamp tools of the trade shown by several along with several methods of measurement and calculating. I will be buying one of the "position finders" myself as it is great for referencing as shown by Robert.
But would it not be even more accurate to state the lower right corner of position F8 for more clarity?