Hard edges.
The Edge Filter tool is very usefull but sometimes it does not do what You want, especialy on complex "twisted" objects. I found You can actually use the tool in a reverse order: pick all edges, make them all hard, use the Edge Filter to pick the edges You want be smooth.

Pages made from the amigaguide version with the help of Mike's
RDAG2HTML
and the fabulous Dietmar's GoldED with the
WWW extension v2.