Scarph Joints 101

Scarph Joints. First off, what is it? A scarph joint in a way of joining two peices of wood so they are flat. The two peices slope in at their edges when they come together. This makes a stronger joint than a butt joint, where the two peices come together squarely.

This would be one half of the joint, with the other lying on top of it. (This was a practice piece.)

So how do you do it?  What I found out is that the joint should be in an 8:1 ratio. So because my wood is 1/4 inch thick, the joint would use two inches of wood on either side. So two inches out from the edge of the wood, you use a planer to create a slope. I had originally been using a hand planer, but I traded that for an electric one for the sake of efficiency.

The planer is the tool in the picture, and it shaves the wood at an angle, very slightly. I kept making cuts that seemed huge, but in fact they were 1/32nd of an inch. The 2x4 behind the planer was there to make sure I did not cut behind the 2" line. 

Then I sanded the joint down, both with this orbital sander, and with sand paper. I almost feel like I'm cheating by using the sander. Hand sanding really makes me feel like I'm doing the building. 

I finished the first piece, and did the second. I lined them up to see how they fit together, and they were uneven and not angled enough. They came together roughly. So I clamped them to the table again, this time side-by-side, and sanded/planed them at the same time. The lines of the layers of the plywood make eyeballing how far you've cut very easy. Now, they come together almost perfectly. 

 Here the two peices are side by side: 

 And here they are held together: 

The next step is to glue them with epoxy, then clamp them and wait for them to dry. And what is epoxy exactly? It's extremely waterproof glue. It can be used for a variety of purposes, as the man who sold it explained, but for boat building, it's the best there is. In addition to the epoxy, I also now own a users manual and a copy of Epoxy Works magazine, both of which were recommended I read before use.