I'm building a king size bed frame, out of white oak, for the first time and thinking about attaching the rails to the posts using 3/8" thread inserts. The rails are 1 1/4" x 8" and the post are 3 pieces of 1 1/4" glued together thus 3 3/4" square. I was going to rout out the inside edge of the posts a 1 1/4" x 8" cutout. This is not a mortise but a cutout so the inside face of the posts and rails are flush. I was then going to attach them with inserts installed in the posts and then running the bolts through the face of the rails.
I didn't want to use bed bolts because I didn't want any bolt heads showing. Do you think the bolts/inserts will pull the rail into the posts together snug enough ? Also, since the posts have 2 vertical glue lines I prefer they aren't on the front side. Thus the inserts would have to be installed on the edges of the 1 1/4" oak that make up the posts. Will the inserts hold just as well in an edge or do they need to be installed in the face ? Thanks for any suggestions.