Just found a stl file for a 1.6mm nut driver specifically listed for RC stuff.
I need to look in my tiny tools drawer in my box when I get home. My great uncle was a diesel mechanic, that loved all things miniature. I think he would have loved scale rc builds. He had a lot of really small...
Maybe my calculator is broken but 1.5 X .03937 comes out to .059055 for me. Which matches the charts rounded .0591.
EDIT: If I'm wrong I wouldn't be surprised. We have a very sick cat at home and I haven't been sleeping much.
I use a cheater chart for stuff like this.
https://www.electriduct.com/Conversion-Chart-Millimeters-Decimals-Fractions.html
Correct though, just a hair smaller than 1/16".
Did find this though...