King Bed Headboard - Part 3: Mortising for the Slats

The design of this headboard includes 11 slats that are oriented vertically between the two horizontal rails.

With 11 slats, there will be 22 mortises

The spacing between the two posts is 72".  I ganged the two rails together to lay out the locations of the slats.  One slat is 8" wide, 6 of them are 5" wide and the remaining 4 are 2 1/2" wide.  This leaves room for 2" between each slat and between the outside slats and the posts.

Laying the slats on a rail to get an idea of the spacing

After marking on the rails' edges where the slats will be positioned, I marked in 1/2" for shoulders of the 5" and 8" slats, and marked in 1/4" for the shoulders of the 2 1/2" slats.  The slats are approximately 3/4" thick and I'll be using a 3/8" chisel for the mortises.  So I set a mortising gauge just wider than the tip of the chisel and marked the mortises in the rails and the tenons for the slats.

Before marking the tenons on the slats, I marked the shoulder lines.
The slats are 11 1/2" long, shoulder to shoulder, plus 5/8" tenons (5/16" for the purpleheart slats).

I started chopping the mortises in the rails, beginning with the one for the center slat.

Chopping the first mortise.  Vertical alignment was aided by a
board clamped to the face of the rail.

I was able to use a router plane to make the mortise bottoms a consistent depth.

Routing the bottom of the relatively shallow mortises.

After chopping the first 6 mortises I changed tactics.  I'd never tried boring out a mortise before, but I tried it here and it worked well for me.  Much quieter than the mallet and chisel.

Boring out a mortise

After paring the walls, checking for square, and paring some more to square them up better, I was happy.

Here's one rail with 11 mortises completed.

Nothing too exciting to see for the tenons.  The shoulders were sawn, the waste was split off, and the final thickness was obtained using a router plane.  Here's a dry fit to see how things are going.

Slats dry-fit to the rails

Next time I'll report on the posts and (hopefully) also fitting the rails and posts together.