eliotandmax
Here's a case where my inexperience paid off: I had only a nice piece of thick plate glass that was about 14 in. square and and an even smaller square of 150 grit sandpaper --perhaps 12 in. square. The plane is about 16 in. long. Also, some kind of intuition had me griping it over the mouth, with elbows locked , and moving in only one direction. So, apparently, I did it just right! But here's another question: what kind of straight edge do you use to judge the flatness? Or do you actually run one of those micrometer dials over it? Also, I read somewhere, that some workers actually take pains to NOT have it flat everywhere. Something about some slight hollows here and there( forget where.)