making of a brass scale.
First I made the scale with windows "paint" - saved as bmp with very high resolution. Inverted black to white and mirrored it.
Printing on a sheet of matt 130g/m paper from Tetenal with high contrast in the size I need for my compass.
Note that you can only use laser or Xerox printer - no inkjet possible.
get a brass plate and clean the surface with acetone (or girls nail enamel remover) - don`t touch it after cleaning !
put the printed scale onto the brass plate and press an iron on (highest temperature) for a couple of minutes. The toner is sticking on the plate.
Let it cool down and drop the plate into a bowl of cold water to remove the paper gently of the plate with your fingers until you can see shiny brass
use the kitchen sink and fill it with boiled water - put a glas vessel into the sink with Natriumperlsulfat until the chemestry has ca. 45-50°C.
tape the areas which you don`t wanna etch with Tesafilm or anything else
hold the plate into the vessel and blow in some air with a drinking straw - do NOT suck ! Check the result each minute til you are happy with it.
rinse the plate with cold water and remove the remaining toner with Aceton - et voila : a nice detailed homebrew compass scale :