I want to smooth only the outer faces of a circle I am currently working on a medal where I want a smooth the extreme outer part of it but without touching the rest especially the upper face.  However even when I add one subdivision modifier, I get the result I want but the upper face grove lines emitting from the central circle are ruined.  A you can see in the photos.

I  have marked the edges as sharp (Edit mode/mesh/shading/sharp) but without a result.
OK, for 3d Print this should work fine:


Add 2 edge loops along the sides.
Press CRTL num plus to extend your selection, so it covers the entire rim
W -&gt; subdivide
Choose these options (lower left at your VP imediately after hitting subdivide)


You might need to tweak the rim, bc. it may become concave. Easiest would probably to delete the new edge loops around the &quot;coin&quot; again.