Now that the headboard and foot board have been assembled, the only thing left to make is the side rails. We’ll be applying the same basic panel design, but with a twist. To begin, cut four pieces of 6/4 lumber to 3.5″ width, the same dimension as the rest of the boards.
The total height of each rail will be 16″. The length of a king size bed is 80″, but I want to leave a little room to make sure sheets and bedspreads can be tucked in (when I make the bed every other month) so I’m going to make them 81″ long.
To get to the 16″ height, we’ll need to subtract out the width of the top and bottom board for a total of 7″. That means our three vertical pieces will need to be 9″ tall, plus 1.5″ to account for the two, 3/4″ dovetails. So, cut 6 pieces of 3.5″ thick lumber to a length of 10.5 inches.
Here’s a visualization of how the pieces comes together (sans paneling, you know how that works by now!).
Joining these pieces will require sliding dovetails. Why use this joint instead of tenons again? Well, The bottom and top cross piece on the head and foot board don’t actually bear a ton of weight, and where they DO it’s all being applied through the tenons down into the posts. Since the tenons go through the post, we don’t have to worry about downward pressure separating that joint.
On the side rail, however, the downward force definitely could separate a simple mortise and tenon over time. So we’re going to use a router to make sliding dovetails.
Start by routing the same 1/2″ groove in all 10 pieces (the four 81″ pieces and the six 10.5″ pieces). Then, swap in a dovetail bit that is 3/4″ wide at it’s widest point. I bought this one. If you use this bit in particular, make sure your router has a 1/2″ chuck.
The two center posts will get mortise and tenon joints in the same way as the head and footboard; the side dovetails will keep the whole thing together, and there’s no way to make a sliding dovetail in the middle of the board.
On the long pieces, we want to hold the groove-side down and route the dovetail in 2.75″. Use the painters tape trick we used on the foot board. Go VERY slow. This is a big bit, and there’s no way to pre-route anything, so take it easy. It should look like this when done.
Next, you’ll want to stand the 10.5″ piece on its end grain, and route a dovetail into it, allowing it to slide into the top and bottom rail. It should look like this:
Make sure to practice this on some scraps and get everything very fine tuned before you route it. The tapered nature of this bit means it’s very hard to just make adjustments and redo the dovetail. Here’s a look at how those ends will slide together:
This next step will vary greatly depending on what kind of bed you have, so I’ll lay out the principals and you’ll have to use some judgement. We’re going to glue and screw two support pieces onto the side rails; these pieces are what the slats will rest on that hold the bed up. We have a 12 inch thick memory foam mattress, which does not use a box spring. So, in my design we will be utilizing 4/4 lumber slats spaced 3″ apart to support the memory foam. If you look at the original inspiration plan, they put this support rail much close to the bottom of the side rail. Why is mine higher? Without the box spring, our bed would be sitting under the top edge of the side rails. So, if you use a box spring, just place this strip on the lower board.
When screwing this piece in, we want to use a piece of strong, sturdy lumber. I chose poplar, in part because I already had some in the house. We want to avoid drilling into the sliding dovetails, because the screws will inhibit natural wood movement on that joint. So, I decided to make the poplar strip 1.25″ wide, set it basically flush with the bottom of the top board, and drill and screw through the top 1/2″ of it using #8 wood screws from Rockler.
But wait!!!! You thought I hated wood screws, didn’t you? Let me explain: my two major complaints were that pocket screws would constrain natural wood movement, and wouldn’t provide enough strength in this application.
I’m not worried about wood movement in this application, because the two pieces I’m joining are being joined with the grain running the same direction. Wood also doesn’t really expand much along it’s length, so there are not going to be any issues here. In the inspiration plans, a lot of times the boards are being joined with grain running perpendicular between the two pieces. That can cause issues, as both boards will want to expand in different directions.
As for strength? The poplar board has been glued to the alder along its entire length, and it’s a face-grain to face-grain glue up, which will be really strong. The screws, then, are almost just little clamps. The majority of the strength here is coming from the large glue surface. Wood glue is much stronger than you’d think! However, end-grain to face-grain glue joints (like some of the ones in the inspiration plan) are not very strong.
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.
Here’s how it should look (after staining and finishing, we’ll get to that!).