Frame D' - assembling and gluing

With the beam and posts for the compression gate laminated and dimensioned, I moved on to assembling all the components that make up frame D’. This is by far the most complex frame so far, combining curved pine members, heavy structural elements, and several plywood panels that all need to come together accurately.

Frame D' - next step is the plywood backpanel

The first challenge was fitting the compression beam to the curved pine pieces at the top of the frame. The plans call for a half-lap joint at each corner, but lacking a more suitable tool, I decided to cut the notches using the multitool. Before touching the real beam, I tested the entire procedure on a scrap piece of wood until I felt confident I could control both depth and alignment. The final result was far from cabinet-maker quality, but given my lack of experience with this kind of joint, it came out more than acceptable and fit properly.

Using the multitool to cut the half-lap joints

In parallel, I cut and shaped the plywood panels for the corners of the frame. This was familiar work by now, using the same approach as on the previous frames: cutting slightly outside the line, dry-fitting, and then refining the shape with a rasp, file, and sandpaper. I also decided to add an extra plywood panel joining the bottom beam to the compression posts. Most photos I’ve seen from other builds don’t show this piece, but structurally it made sense to me, as it creates a much stronger and better-defined load path between these elements.

Top plywood panel (before precise shaping with rasp and file)

While working on the upper structure, I was also trying to source the hardwood required for the bottom beam. The plans specify oak, but when I asked the yard owner, he didn’t have any available. Instead, he suggested Kambala, which he described as superior to oak for this application and readily available in the yard. I wasn’t familiar with the name, so I did some research and learned that Kambala is the Portuguese name for Iroko. I then remembered that Janusz mentions Iroko in his blog as an excellent alternative when oak is hard to find, so the choice was an easy one.

Cutting the Iroko beam

With the yard owner’s help, we selected a large piece of Iroko and cut it into a rough beam on the bandsaw. After that, a few passes through the jointer planer flattened one face, and the thickness planer brought the piece to its final dimensions. The result was a beautiful, dense piece of wood, perfectly suited for the floor of the compression gate.

Jointer planer - creating a flat side

Iroko floor beam

The next step was cutting the ends of this beam at an angle to match the hull shape. I first tried doing this manually, but between the thickness of the wood and the steep angles required, it quickly became clear that the results wouldn’t be good enough. Instead, I resorted to an idea I had been saving for the stringers and built a simple jig for the table saw. Using a perfectly square piece of MDF, I cut a groove along about half its length; this groove marks the exact path of the blade. By aligning the beam with the groove and securing it using a screwed block and a clamp, I was able to safely and accurately cut the required angles. The results were excellent and far better than anything I could have achieved by hand.

Jig for cutting at an angle with the table saw

With all the pieces finally ready, I moved on to glue-up. I followed the same procedure described in earlier posts: sanding and cleaning all contact surfaces, applying unthickened epoxy to both sides, thickened epoxy to one surface, and then gluing and screwing the plywood panels in place. Where appropriate, I used weights to apply pressure, both to improve bonding and to push the sides of the bottom beam firmly against the compression posts.

Gluing everything

This frame has been a real step up in complexity, introducing several new challenges compared to the earlier ones. I’m glad I left it for last, as the experience gained from building the previous frames made it far more manageable. Even so, there’s still some work left to do before I can call frame D’ finished — most notably adding the plywood bulkhead on the opposite side. I’ll cover that in the next post.