Help, please: Copper Coin

[Holcberg]

Hello,
I use Gravermax Sc,
I am interested in engraving a single decoration in the form of a leaf or a spiral on a copper coin with a diameter of 22 mm.
Do you perform a certain preparation before engraving, i.e. smoothing the coin so that there is no resistance or deviation of the movement during engraving?
I use 3.5X magnification with surgical loupes and HSS gravers, I do the sharpening manually without a jig

 

[mtlctr]

Level surface.

 

[monk]

the prep needed depends on the final result you seek. i agree with mtlctr. why not flatten it first.

 

[DaveatWeirs]

flat is better, or even just roughly flattened. if you engrave over it you'll need to compensate for the changes in height of the design on the coin as this will affect the width of your lines: unless you're 100% accurate, as the metal raises up your lines get wider and as they drop away they get thinner.
engraving over the design already on a coin can be good practice for really getting the feel/instinct of when the graver is digging deeper or about to pop out cuz it's too shallow, but doesn't make for pretty coins

 

[Holcberg]

Thanks for the comments and reference