This is my next project, and it's a paying one! This is a lawn sign for a local financial advisor. He has secured the actual signs, painted metal, sign permits and dig line mark outs. I'll supply the construction and installation.
The post is a full 6x6 cedar timber and the arms are nominal 4x4 cedar. I'm thinking about white oak for the sign frames. The arms will mortise into the post with 2 1/2" square tenons that are 1 3/4" deep. The chain is a substantial link and I'll use an angled hole at the end of the arm with a counter set nut to pull the slack out. If that's not clear sorry. The pictures will make it cleared than I can with words.