There are some cheap V bits on ebay that have a very small tip (0.1 mm). This link is for Ebay.fr, but you can find similar bits everywhere on the Internet.
I use them for engraving on brass, plastics, even as hand tools.
They are very precise, and you can use them with Carbide Create (Pocket, 0.15mm Depth, 0.15mm Depth of cut).
If your text is very tall, use your 1/16" ball nose cutter to clear the bulk of the material and then use these for details.