The middle string s/b 'd' not 'D'. The big 'D' is the one below middle C, the lower case is the one just above middle C. You would be looking at Gdg, not GDg. The easiest way to remember is do the strings in order, either up or down.The Strothers calculator usually is a bit on the light side.
The layout on the calculator popup is lower notes [larger strings] to the bottom and higher notes [small strings] to the top, all in the right order.
As far as the 'F' goes, try taping a 2" straightened paper clip or a toothpick in place as a temporary fret. If you have access to a micrometer/caliper, frets are about .040"-.043" high.
updated by @skip: 06/26/16 09:21:17PM
