In the penultimate machine that I did, it would be necessary to write lowercase text and figures in silver commemorative plates.
In these plates the silver layer is very thin, making it impossible to write on with a rotating cutter router; because any undulation on the board or the minimum misalignment caused imperfections in recording and left exposed to the brass plate material.

As interim test build with a broken cutter tool scratch with springs (figure), it worked perfectly for large fonts, but due to a small gap between the parties failed to small fonts.



The final solution was to use this tool:
http://www.tormach.com/store/index.php?app=ecom&ns=prodshow&ref=32447
This tool uses a diamond scriber, the result was very good

 

Result of engraving with my homemade tool (aluminum materials)

 

For those who want to make a engraving tool, attached the SKP design
Note: This tool can not rotate on the router, it can escape and cause an accident (only serves to trace).
Ideally holding it in a fixed support