As you can imagine, the process for creating the headboard is identical to making the foot board, but the dimensions are different. Use the same distance between posts, and still put the top crossbeam on the very top of the posts using dovetails.
The bottom crossbeam, however, will now be positioned with the bottom of the mortise at 16.5″ from the bottom of the post. That way, when you add the 3.5″ height of the crossbeam, the top of the crossbeam will be even with the top of the side rail (which will be 16″ tall and start 4″ from the floor).
I’m not going to post any pictures of this, the foot board post goes into all the details. The only thing that really changes is the height. So, go out there and build it! Side rail post coming soon, then staining and finished before assembly!
Important note: Do not glue the joints together before staining and finishing the wood. We want to make sure we get the stain in all the nooks and crannies, and if we glue first, the glue might make the stain look blotchy.